ALBERT

Description: 〈p〉Publication date: February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 173〈/p〉 〈p〉Author(s): Bao-jun Zhang, Guang-hui Zhang, Han-yue Yang, Hao Wang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Steep gully slopes are widespread and have been recognized as the main sediment source on the Loess Plateau. Different vegetation growth may lead to the differences in soil properties and plant roots, and thus likely affects soil resistance to flowing water erosion, reflected by rill erodibility and critical shear stress. However, few studies have been conducted to evaluate this effect on steep gully slopes on the Loess Plateau of China. This study was performed to investigate the effects of vegetation growth on soil resistance to flowing water erosion on steep gully slopes, and quantify the main potential influencing factors on the Loess Plateau. Three typical shrub communities and four typical grass communities that distributed on different gully slopes were selected. 240 undisturbed soil samples were collected from these seven gully slope lands and one slope farmland (control), and were subjected to detachment by overland flow under six different shear stresses (6.64 to 17.85 Pa). The results showed that the mean detachment capacity of slope farmland was 6.9 to 47.8 times greater than those of steep gully slopes covered with different plant communities. The rill erodibilities of steep gully slopes covered with different plant communities reduced greatly by 77.0% to 95.1% compared to the control slope. The critical shear stress of slope farmland (2.72 Pa) was only 57.2% and 39.6% of that of shrubland (4.76 Pa) and grassland (6.88 Pa). Both shrub and grass communities were effective in reducing soil detachment capacity and rill erodibility, and increasing critical shear stress on steep gully slopes. But the effects were more obvious for the grass communities. The differences in rill erodibility between slope farmland and gully slope lands were mainly explained by the changes in root mass density (82.4%). Plant roots had strong direct effects on increasing soil cohesion (0.78), organic matter content (0.56), and water stable aggregation (0.92). Rill erodibility was negatively related to root mass density as an exponential function (〈em〉p〈/em〉 〈em〉〈〈/em〉 0.05), and soil cohesion and water stable aggregation as power functions (〈em〉p〈/em〉 〈em〉〈〈/em〉 0.05). Critical shear stress was positively related to root mass density and soil water stable aggregation following a logarithmic function.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 173〈/p〉 〈p〉Author(s): Shi Qi, Jinzhu Ma, Xinying Ling, Qi Feng, Jianhua He, Heping Shu, Bing Jia〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In the southwestern Tengger desert in northwestern China, nitrate circulation processes in the unsaturated zone and associated driving factors were studied using water chemistry and stable isotope techniques. At unvegetated sand sites, NO〈sub〉3〈/sub〉〈sup〉−〈/sup〉 content increases from the south to north in the desert. Additionally, a negative correlation (R〈sup〉2〈/sup〉 = 0.90, P 〈 0.005) was evident between the stability of soil NO〈sub〉3〈/sub〉〈sup〉−〈/sup〉 and elevation, suggesting that NO〈sub〉3〈/sub〉〈sup〉−〈/sup〉 storage in soil is significantly influenced by precipitation and temperature. And a significant positive correlation between mNO〈sub〉2〈/sub〉〈sup〉−〈/sup〉/Cl〈sup〉−〈/sup〉 in unsaturated zone and elevation (R〈sup〉2〈/sup〉 = 0.50, P 〈 0.0001), indicating both nitrification and denitrification are strongly in the south of desert, however, the nitrification plays a dominant role in the north of desert. Isotopic analyses (δ〈sup〉15〈/sup〉N-NO〈sub〉3〈/sub〉〈sup〉−〈/sup〉, δ〈sup〉18〈/sup〉O-NO〈sub〉3〈/sub〉〈sup〉−〈/sup〉, and δ〈sup〉18〈/sup〉O-H〈sub〉2〈/sub〉O, δ〈sup〉2〈/sup〉H-H〈sub〉2〈/sub〉O) of soil pore-water showed that the two dominant NO〈sub〉3〈/sub〉〈sup〉−〈/sup〉 sources were the mixing of atmospheric deposition and soil nitrification, and that the NO〈sub〉3〈/sub〉〈sup〉−〈/sup〉 circulation at the vegetated sand sites was affected by vegetation and animals. Additionally, local environmental conditions lead to complex driving factors, such as the abiotic process of ammonia volatilization of NO〈sub〉3〈/sub〉〈sup〉−〈/sup〉 circulation, which resulted in the 〈sup〉15〈/sup〉N enrichment and 〈sup〉18〈/sup〉O depletion of residual nitrate in the unsaturated zone of one of the soil profiles. Denitrification was noted in the deep unsaturated zone of two profiles, indicating that the N loss resulted from abiotic versus biotic processes. Analyses of the stable isotope results and the distribution characteristics of NO〈sub〉3〈/sub〉〈sup〉−〈/sup〉 and Cl〈sup〉−〈/sup〉 suggests leaching of soil NO〈sub〉3〈/sub〉〈sup〉−〈/sup〉 as a result of NO〈sub〉3〈/sub〉〈sup〉−〈/sup〉 in unsaturated zone poses a potential threat to groundwater quality in Dengmaying region. This study suggests that NO〈sub〉3〈/sub〉〈sup〉−〈/sup〉 circulation in the unsaturated zone responds to climate characteristics in the desert ecosystem, and to provide useful information for the protection of groundwater quality in arid desert regions.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 173〈/p〉 〈p〉Author(s): Estela Luna, Claire Jouany, Carmen Castañeda〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In arid and semiarid environments, saline wetlands are both high-value habitats threatened by landscape transformations, and a constraint to agricultural production. There is a lack of knowledge about nutrients distribution in intermittently flooded environments subjected to soil and water salinity. The aim of this work was to characterize soil and plant nutrient status along soil transects at the interface between agricultural land and saline wetlands. These aspects were studied in Guallar and Gallocanta, two Ramsar saline wetlands in NE Spain that represent arid and semiarid conditions, respectively. Soils were characterized for nitrogen (N) and phosphorous (P) status; crop and natural vegetation nutrient status was measured with P Nutrition Index (PNI) and Nitrogen Nutrition Index (NNI). Soil salinity (EC1:5) increases towards the halophyte areas, reaching 5.4 dS m〈sup〉−1〈/sup〉 in Guallar and 3.7 dS m〈sup〉−1〈/sup〉 in Gallocanta. On average, the soils are loams or sandy loams. Carbonate-rich soils are common (39% mean calcium carbonate equivalent) and some soils in Guallar have a high gypsum content (up to 72%). The soils have a low to moderate cation exchange capacity regardless of soil salinity, with a maximum of 14 cmol〈sup〉+〈/sup〉 kg〈sup〉−1〈/sup〉 in the soil with the highest organic matter content (3.8%). Overall, cereal soils show total P and N contents within the normal range for agricultural soils, although the available P is above the requirements for cereals, up to 67 mg kg〈sup〉−1〈/sup〉. The difference in soil nutrients between cropped and halophyte land is more noticeable when it comes to total and available P content than for N levels. The relatively high nutrient content in some halophyte soils and the total and available P gradients along the soil transects, reflect downslope nutrient movement towards the lake. Halophyte soils can accumulate between 11% and 71% of the available P found in cropped soils. No relationship was found between the soil nutrient content and that of plants, nor between these two parameters and soil salinity. NNI and PNI indicate non-limiting nutrient status for cereals grown in Gallocanta and nutrient limitation in Guallar, probably related to the high gypsum content, and/or soil salinity. Studying the plant available nutrient content in arid and saline soils, at the interface between halophytes and crops, is crucial for improving land management strategies and reconciling production and conservation in protected saline habitats.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 172〈/p〉 〈p〉Author(s): Jinchang Li, Yuan Wang, Lisha Zhang, Liuyan Han, Guangyin Hu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Under a background of a significantly warming climate, current aeolian desertification in China's northeastern Tibetan Plateau (NETP) has been widely studied, but disagreements related to its causes continue to persist. In order to understand the present through the past, this study determined the various phases of aeolian desertification in the NETP based on the statistical analysis of 40 optically stimulated luminescence (OSL) aeolian sand dates from 23 aeolian sections. Because the redistribution of aeolian sand by wind processes can reduce the number of older sand dates, this research only affects exactly the past millennium. Following this, we analyzed the relationships between aeolian desertification phases in conjunction with reconstructed climatic data. Results revealed three distinct aeolian desertification phases that approximately correspond to 1480 CE, 1680 CE, and 1800 CE, respectively. By comparing these dates to well-established paleoclimate records, we determined that these three aeolian desertification phases all occurred under a cold and dry climate background. Accordingly, aeolian desertification in the NETP today under its current warm and wet climate background can therefore be attributable to irrational human activities rather than rising temperatures. Accordingly, we can infer that under the current warmer and wetter climate background, aeolian desertification in the NETP today can be reversed as long as human activities remain moderate, even without the implementation of artificial revegetation initiatives.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S034181621830417X-ga1.jpg" width="500" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 172〈/p〉 〈p〉Author(s): Yitong Wang, Kai Yang, Zejun Tang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A field experiment was conducted to investigate the resistance to wind erosion of consolidated soil layer (CSL) on the edge of Ulan Buh Desert in Inner Mongolia, China under natural conditions during Aug. 2015–Apr. 2016. The CSLs consisted of sandy soil, fly ash (FA) (5%, 10% and 15% (w/w) soil) and polyacrylamide (PAM) (0.05% and 0.1% (w/w) soil). The experimental site was divided equally into Regions A and B where dry FA and PAM powder were applied in two ways in mid-Jul. 2015. In Region A, FA and PAM were mixed homogeneously with the 0–0.3 m depth topsoil. In Region B, FA alone was mixed homogeneously with the 0–0.3 m depth topsoil. PAM was then scattered uniformly on top of the surface layer. Finally, CSLs were formed by spraying an appropriate amount of water onto the surface to dissolve PAM fully and being equilibrated for one week to achieve a moisture content close to the initial soil moisture content (0.6%). It was found that during 2–26 Aug. 2015, the wind erosion rate (WER) was reduced most significantly by 77% in CSL (10%FA + 0.05%PAM) in Region A and by 58% in CSL (10%FA + 0.1%PAM) in Region B compared with control (CK) (WER = 10.2 kg/m〈sup〉2〈/sup〉). However, during 3–27 Sep. 2015, there was no significant difference in WER between treatments in Regions A and B compared with CK (WER = 1.4 kg/m〈sup〉2〈/sup〉). Whereas, during the following longer period of wind erosion (〈em〉viz.〈/em〉 27 Sep. 2015–21 Apr. 2016), the WER was reduced most significantly by 69% in CSL (5%FA + 0.1%PAM) in Region A and by 32% in CSL (5%FA + 0.05%PAM) in Region B compared with CK (WER = 80.7 kg/m〈sup〉2〈/sup〉). The resistance to wind erosion of CSL in Region A was much stronger than in Region B. The WER of CSL was influenced by wind conditions including wind speed and direction. Precipitation also had an impact on the WER of CSL as the cohesive effect of PAM can be influenced by precipitation. The CSL as a mixture of sandy soil, FA and PAM is recommended for wind erosion control.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S034181621830345X-ga1.jpg" width="500" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 172〈/p〉 〈p〉Author(s): Craig M. Hall, Heather N. Webb, Gary H. Girty, Amir A. Allam, Thomas K. Rockwell〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Lying between the Elsinore and San Jacinto faults, ~0.5 km SE of Roundtop, is a tonalitic corestone perched precariously on an exhumed corestone base. Such features are referred to as precariously balanced rocks (PBRs). Cosmogenic 〈sup〉10〈/sup〉Be data listed in an online abstract suggest a tentative exhumation age of the PBR near Roundtop at ~35,000 years ago. The absence of PBRs adjacent to the Elsinore and San Jacinto faults implies that they were shaken free from their perches during ground shaking. Alternatively, their absence may reflect a more highly fractured and intensely weathered terrane. Because the weathering histories of PBRs have not been studied previously, we analyzed the texture, clay mineralogy, and geochemistry of the Roundtop PBR to answer several basic questions. Can the characteristics of the regolith that once encased the precariously balanced rock be reconstructed? What chemical processes operated in the regolith prior to exhumation, and are these processes still occurring? Following exhumation, did new fracture development modify the original regolith? To answer these questions, we extracted three ~1 m long cores from the PBR near Roundtop, and collected 23 saprock and 9 pebbly sandy loam samples from a trench excavated near the base of the corestone platform. Plagioclase and biotite alteration, along with the concomitant loss of Ca, Na, Sr, Ba, K, Mg, Mn, Nb, and P mass, are the primary evidence of weathering intensity within the saprock. Additionally, the presence of mostly kaolinite, and lesser quantities of mixed-layer biotite/smectite in the saprock, along with the above observations and data, point to significant fluid/rock interations during saprock development. Subsequent formation of pebbly sandy loam appears to have been accomplished primarily through pedoturbation within the uppermost portions of the underlying already weathered saprock, and produced little additional chemical weathering. Hence, our data support the general idea that Roundtop is an area of weak ground shaking, and that since current exhumation little weathering has affected this PBR locality.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 172〈/p〉 〈p〉Author(s): K. Hlavčová, M. Danáčová, S. Kohnová, J. Szolgay, P. Valent, R. Výleta〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The paper focuses on the generation of floods as a principal soil threat and on soil erosion as an additional soil threat on arable lands of hillslope areas. As the most important component of floods causing the degradation of soils on arable lands, surface runoff is analysed in this study. The protective effect of crop management on the generation of surface runoff and sediment transport on arable lands is estimated on a plot and slope scale. The site of the case study, which is located in the Myjava river basin in western Slovakia, is a hilly agricultural field with an area of 29 ha; it is characterised by arable soil, extreme erosion processes, and muddy floods. Field rainfall simulation experiments were combined with physically-based modelling for studying the formation of surface runoff under various soil covers. The field experiments consisted of simulating runoff generation from artificial rainfalls using the Eijkelkamp rainfall simulator on experimental plots with a focus on estimating the volume of surface runoff, the mass of sediments transported by the surface runoff, and the time to runoff. The volumes of the surface runoff and the values of the time to runoff have been applied in the parameterisation of the SMODERP physically-based hydrological model. The hydrological modelling of the surface runoff on the selected slope profile quantified the protective effect of various soil covers on reducing surface runoff. The outcome of the modelling was the maximum allowed lengths of the slope that represent the crucial values for flood and erosion control. When exceeding these critical values, protective measures, e.g., vegetation strips, should be proposed.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 172〈/p〉 〈p〉Author(s): Chang-An Liu, Yu Nie, Xin Rao, Jian-Wei Tang, Kadambot H.M. Siddique〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Rubber-based (〈em〉Hevea brasiliensis〈/em〉) agroforestry systems are the best way to resolve the environmental problems caused by rubber monoculture. Rubber–〈em〉Flemingia macrophylla〈/em〉 (nitrogen-fixing plants) systems have become popular in Xishuangbanna, Southwest China. Soil water content and exchangeable cations (Ca〈sup〉2+〈/sup〉, Mg〈sup〉2+〈/sup〉, K〈sup〉+〈/sup〉, and Na〈sup〉+〈/sup〉) are important for sustainably managing forest ecosystems. In this study, we investigated the responses of soil water content and exchangeable cations in rubber and rubber–〈em〉Flemingia macrophylla〈/em〉 systems. Soil water content increased in the 0–90 cm soil layer as the rubber plantations aged, and the mature rubber plantations had similar soil water storage to rainforests. The rubber plantations use soil water in the 30–90 cm soil layer to avoid drought stress during the long, dry season. The introduction of 〈em〉Flemingia macrophylla〈/em〉 to the young rubber plantations significantly increased soil water depletion in the 30–90 cm soil layer. The introduction of 〈em〉Flemingia macrophylla〈/em〉 to the mature rubber plantations had no significant effects on soil water in the 0–90 cm soil layer. The introduction of 〈em〉Flemingia macrophylla〈/em〉 to the differently aged rubber plantations mitigated soil acidification by decreasing nitrogen inputs. The total exchangeable cations in the 0–90 cm soil layer sharply decreased as the rubber plantations aged due to the acceleration of soil acidification. When soil pH was below 5.5, 7.85 cmol kg〈sup〉−1〈/sup〉 of soil exchangeable cations were released when the pH decreased by one unit. However, the introduction of 〈em〉Flemingia macrophylla〈/em〉 to the differently aged rubber plantations effectively reduced the release of soil exchangeable cations by mitigating soil acidification. In conclusion, rubber–〈em〉Flemingia macrophylla〈/em〉 systems can mitigate soil acidification and reduce the release of soil exchangeable cations relative to rubber monoculture.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S034181621830362X-ga1.jpg" width="500" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 172〈/p〉 〈p〉Author(s): Diego Luciano do Nascimento, Alessandro Batezelli, Francisco Sérgio Bernardes Ladeira〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Rhizoliths are organosedimentary structures produced by plants and are an important proxy for paleoenvironmental reconstructions because the differences in the morphology of rhizoliths and their rooting depths can be used to interpret soil humidity regimes, overall biomass at the soil surface, and the behavior of the water table. With the objective of advancing knowledge on rhizoliths, a study was performed on the macromorphological and micromorphological characterizations of the rhizoliths preserved in the thirty-one paleosols of the Marília Formation in Minas Gerais, southeastern Brazil. Based on the topological and architectural attributes of rhizoliths, and on their possible functional adaptations, such as mycorrhizal associations, three different types of rhizoliths are described in this study and represent at least three different plants: rhizohaloes, root casts and rhizocretions. Well-developed paleosols with nodular horizons contain the higher density of long root casts, indicating a seasonally dry environment, because the root casts present two meters in length. These adaptations are associated with an exploitation of a lowered water table during most times of the year. The higher density of rhizoliths indicates an area with agglomerated arboreous arbustive vegetation cover. Paleosols with chalky horizons also show a high density of root casts, indicating a landscape with high plant density that is adapted to drained soils, but with a seasonally elevated water table or the influence of ephemeral flows, given the proximity to the flow channels. The poorly drained paleosols with redoximorphic features show the lowest density of rhizoliths, thus indicating an incipient vegetation in response to near-surface water table and waterlogged soils in a distal floodplain. The rhizogenic laminar horizons have developed near fluvial channels with frequent sedimentary input, resulting in a sequence of laminar horizons composed of rhizocretions that are separated by sandy deposits or poorly developed pedogenic horizons. The micromorphological analysis on the rhizogenic laminar calcretes showed biogenic features, such as alveolar septal structures, calcified filaments, microcodium, calcified cells and pisoliths. Despite the scarce paleobotanical findings in the Marília Formation, the results obtained indicate an ecosystem that was composed of plants varying from herbaceous to arboreous, with an environment similar to modern semiarid shrublands.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0341816218304181-ga1.jpg" width="407" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 172〈/p〉 〈p〉Author(s): Yiwei Lyu, Shan Zheng, Guangming Tan, Caiwen Shu, Qi Han〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉To investigate the evolution characteristics of the Yichang–Chenglingji Reach (YCR) of the Middle Yangtze River and develop simulation methods, the temporal and spatial morphodynamic adjustments of the YCR were analysed comprehensively on the basis of runoff, sediment load, and cross-sectional profiles data at 220 cross sections from 2002 to 2016. Results showed that significant channel degradation has occurred in the YCR, especially in the low-flow channels, due to a drastic reduction in sediment yield since the operation of the Three Gorges Project (TGP). The variations of upstream flow and sediment regimes would drive equilibrium channels to become increasingly narrow and deep, and the current bankfull width and depth were less than their equilibrium counterparts in the recent period. However, the recent channel evolution was mainly characterized by the prominent channel deepening via a one-way deformation due to the large-scale bank revetments within the YCR, where the reach-scale bankfull depth increased by 1.6 m in the span of 15 years. A semi-empirical method for determining the equilibrium values of channel degradation and aggradation volume at the YCR was proposed on the basis of a comprehensive analysis of the effects of flow, sediment concentration, sediment gradation, and water depth. Moreover, the equilibrium values of the channel width and depth were estimated with the Least Action Principle method. The calculation methods for the equilibrium width, depth, width/depth ratio, and aggradation/degradation volume were combined with the Delayed Response Model (DRM). Then, the methods for calculating the variations in channel geometry and aggradation/degradation volume were derived. Results showed that the proposed methods effectively simulated the channel geometry and cumulative erosion volume in the YCR from 2002 to 2016. In addition, the response of the channel evolution in the YCR was closely related to the previous four-year hydrological conditions, implying that channel evolution may lag behind the variations of flow and sediment discharges.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 172〈/p〉 〈p〉Author(s): Andre Acksel, Luise Giani, Carolin Stasch, Peter Kühn, Sebastian Eiter, Kerstin Potthoff, Tom Regier, Peter Leinweber〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Some previous studies showed that the formation of several deep dark humus-rich topsoils in Northern Europe was strongly influenced by the application of different organic materials by anthropogenic activities in former times. Such topsoils classified as plaggic Anthrosols also occurred in the Jæren region in SW Norway. However, source material and formation time of these Plaggic Anthrosols have not yet been clarified. Close to this region we found further humus-rich topsoils in the Karmøy municipality (2 sites at main island of Karmøy and 1 site at Feøy). These soils show a thick humus-rich topsoil up to 30 cm, and their formation cannot only be explained by natural conditions. We analyzed the molecular signature of the soil organic matter (SOM) by benzene polycarboxylic acids (BPCA), non-targeted bulk SOM mass spectrometry, δ〈sup〉34〈/sup〉S and 〈sup〉14〈/sup〉C AMS dating in order to determine source materials and the age of the SOM. The black carbon (BC) contents of the plaggic soils in Jæren (mean 3.4 g kg〈sup〉−1〈/sup〉) deliver clear evidence for inputs of combustion residues from ancient fire management and/or from settlements. The C-XANES and Py-FIMS-spectra reveal relative enrichments of aromatic C and heterocyclic N compounds in the plaggic soils corresponding to the BC contents. In contrast, the humus-rich topsoils in Karmøy seem to be unaffected by fire management due to the low BC contents (mean 0.6 g kg〈sup〉−1〈/sup〉) and the relative low portions of aromatic C and heterocyclic N compounds from C-XANES and Py-FIMS. The δ〈sup〉34〈/sup〉S isotope signature of the SOM ranged from 10.6 to 15.2‰ in the soils at the islands and 10.0 to 13.5‰ in Jæren, corresponding to the Anthrosols in the Baltic Sea region (Median: δ〈sup〉34〈/sup〉S = 11.5‰) and suggest an input of marine biomass (δ〈sup〉34〈/sup〉S of seaweed = 20‰). The AMS 〈sup〉14〈/sup〉C dating and complementary archaeological literature implied that the soils in Jæren and Karmøy have been formed between the Roman Iron Age (500 BC to AD 500) and the Viking Age (AD 800 to AD 1,000). Our results provide strong evidence for an anthropo-pedogenesis of the humus-rich topsoils in Karmøy and indicate parallels to the plaggic soils in Jæren as well as to Anthrosols in the Baltic Sea region. Therefore, we propose to classify the humus-rich topsoils in Karmøy as Anthrosols.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 173〈/p〉 〈p〉Author(s): Israel Carmi, Joel Kronfeld, Murray Moinester〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Inorganic carbon, as allogenic and pedogenic carbonates mixtures, can be a significant component of arid and semi-arid zone soils. It has been claimed, that the formation of pedogenic carbonates does not sequester atmospheric carbon dioxide, when formed from the preexisting limestone: Ca〈sup〉+2〈/sup〉 + 2HCO〈sub〉3〈/sub〉〈sup〉−〈/sup〉 → CaCO〈sub〉3〈/sub〉 ↓ + CO〈sub〉2〈/sub〉 ↑ + H〈sub〉2〈/sub〉O. But if the cation is derived from a non‑carbonate source sequestration can occur. Among the unconsidered sources in nature are the contribution of Ca〈sup〉+2〈/sup〉, released from adsorption sites on the clay surfaces. Analysis of DIC, δ〈sup〉13〈/sup〉C and Δ〈sup〉14〈/sup〉C data show in the present study that sequestration does occur within the unsaturated zones (USZ) in a semiarid region: 1) the DIC is depleted as carbonate precipitates into the USZ, 2) the released CO〈sub〉2〈/sub〉, does not immediately return to the atmosphere (except for the samples nearest to the surface) but recycles to the soil-gas of high CO〈sub〉2〈/sub〉 partial pressure, and 3) that radiocarbon, which is generated only in the overlying atmosphere, and exhaled into the USZ by roots and the decay of soil organic matter, is incorporated within the calcite mineral. Thus, a net sequestration of atmospheric CO〈sub〉2〈/sub〉 does occur.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 25 April 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA〈/p〉 〈p〉Author(s): C.J. Williams, Frederick B. Pierson, Sayjro K. Nouwakpo, Osama Z. Al-Hamdan, Patrick R. Kormos, Mark A. Weltz〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Pinyon (〈em〉Pinus〈/em〉 spp.) and juniper (〈em〉Juniperus〈/em〉 spp.) woodland encroachment has imperiled a broad ecological domain of the sagebrush steppe (〈em〉Artemisia〈/em〉 spp.) ecosystem in the Great Basin Region, USA. As these conifers increase in dominance on sagebrush rangelands, understory vegetation declines and ecohydrologic function can shift from biotic (vegetation) controlled retention of soil resources to abiotic (runoff) driven loss of soil resources and long-term site degradation. Scientists, public land management agencies, and private land owners are challenged with selecting and predicting outcomes to treatment alternatives to improve ecological structure and function on these rangelands. This study is the first of a two-part study to evaluate effectiveness of prescribed fire to re-establish sagebrush steppe vegetation and improve ecohydrologic function on mid- to late-succession pinyon-and juniper-encroached sagebrush sites in the Great Basin. We used a suite of vegetation and soil measures, small-plot (0.5 m〈sup〉2〈/sup〉) rainfall simulations, and overland flow experiments (9 m〈sup〉2〈/sup〉) to quantify the effects of tree removal by prescribed fire on vegetation, soils, and rainsplash, sheetflow, and concentrated flow hydrologic and erosion processes at two woodlands 9-yr after burning. For untreated conditions, extensive bare interspace (87% bare ground) throughout the degraded intercanopy (69–88% bare ground) between trees at both sites promoted high runoff and sediment yield from combined rainsplash and sheetflow (~45 mm, 59–381 g m〈sup〉−2〈/sup〉) and concentrated flow (371–501 L, 2343–3015 g) processes during high intensity rainfall simulation (102 mm h〈sup〉−1〈/sup〉, 45 min) and overland flow experiments (15, 30, and 45 L min〈sup〉−1〈/sup〉, 8 min each). Burning increased canopy cover of native perennial herbaceous vegetation by 〉5-fold, on average, across both sites over nine growing seasons. Burning reduced low pre-fire sagebrush canopy cover (〈1% to 14% average) at both sites and sagebrush recovery is expected to take 〉30 yr. Enhanced herbaceous cover in interspaces post-fire reduced runoff and sediment yield from high intensity rainfall simulations by 〉2-fold at both sites. Fire-induced increases in herbaceous canopy cover (from 34% to 62%) and litter ground cover (from 15% to 36%) reduced total runoff (from 501 L to 180 L) and sediment yield (from 2343 g to 115 g) from concentrated flow experiments in the intercanopy at one site. Sparser herbaceous vegetation (49% cover) and litter cover (8%) in the intercanopy at the other, more degraded site post-fire resulted in no significant reduction of total runoff (371 L to 266 L) and sediment yield (3015 g to 1982 g) for concentrated flow experiments. Areas underneath unburned shrub and tree canopies were well covered by vegetation and ground cover and generated limited runoff and sediment. Fire impacts on vegetation, ground cover, and runoff and sediment delivery from tree and shrub plots were highly variable. Burning litter covered areas underneath trees reduced perennial herbaceous vegetation and increased invasibility to the fire-prone annual cheatgrass (〈em〉Bromus tectorum〈/em〉 L.). Cheatgrass cover increased from 〈1% pre-fire to 16–30%, on average, post-fire across the sites and was primarily restricted to areas around burned trees. High herbaceous cover (73%) under burned trees at the less degraded site resulted in similar low total runoff and sediment from concentrated flow experiments as pre-fire (136–228 L, 204–423 g). In contrast, fire-reduction of litter (from 79% to 49%) resulted in increased total runoff (from 103 L to 333 L) and sediment yield (from 619 g to 2170 g) from concentrated flow experiments in burned tree areas at the more degraded site. The experimental results demonstrate pinyon and juniper removal by prescribed fire can effectively re-establish a successional trajectory towards sagebrush steppe vegetation structure and thereby improve ecohydrologic function. Responses to burning at the more degraded site suggest results should be interpreted with caution however. Although burning substantially increased perennial grass cover and reduced fine-scale runoff and erosion at the more degraded site, poor sagebrush recovery, delayed litter recruitment, and persistent high concentrated flow erosion at that site suggest not all sites are good candidates for prescribed fire treatments. Furthermore, high levels of cheatgrass in burned tree areas (~30% of area) at both sites increases wildfire risk, but cheatgrass is expected to decline over time in absence of fire. Our results in context with the literature suggest fire-surrogate tree-removal treatments (e.g., tree cutting or shredding) may be more appropriate on degraded sites with limited pre-treatment sagebrush and perennial herbaceous vegetation and that seeding may be necessary to improve post-fire establishment of sagebrush steppe vegetation structure and associated ecohydrologic function under these conditions. Lastly, vegetation, runoff, and erosion responses in this study are not directly applicable outside of the Great Basin, but similar responses in woodland studies from the southwestern US suggest potential application of results to woodlands in that region. The concept of re-establishing vegetation structure to improve ecohydrologic function is broadly applicable to sparsely vegetated lands around the World.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 172〈/p〉 〈p〉Author(s): Xuemei Mei, Lan Ma, Qingke Zhu, Bai Li, Dong Zhang, Huifang Liu, Qianing Zhang, Qingping Gou, Mingshuang Shen〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Soil water storage (SWS) is a critical water resource for vegetation growth in the Loess Plateau. Changes in SWS during the growing season can reflect soil water depletion or recharge conditions in different hydrological years. This study investigated the soil water in three hillslopes covered with artificial forest, natural forest and natural grass in May and October of 2015–2017. Both path analysis and stepwise multiple linear regression were used to determine the direct and indirect effects of most important variables and develop a model for predicting changes in SWS. The results showed that compared with natural forestland and grassland, artificial forestland had low soil water, but deep SWS maintained a balance of inputs and outputs. In all soil layers, during the growing season, total precipitation (X〈sub〉4〈/sub〉) was the most important variable affecting changes in SWS. The changes in SWS in surface soil layers were affected by more environmental factors than in deeper soil layers. The natural grassland (X〈sub〉3〈/sub〉) and slope position (X〈sub〉12〈/sub〉) have different degree of direct and indirect effects by means of antecedent soil water content (X〈sub〉5)〈/sub〉, even though their correlations were not significant. In addition, changes in SWS at the 0–100 cm, 100–200 cm and 0–400 cm soil layers were adequately predicted using the multiple regression equation, in which R〈sup〉2〈/sup〉 reached values from 73.4–93.0%. The model simulating the changes in SWS during the growing season can improve understanding on whether rainfall infiltration can replenish soil water depletion.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 172〈/p〉 〈p〉Author(s): Fengyan Zhao, Yongyong Zhang, Feike A. Dijkstra, Zhijun Li, Yueqi Zhang, Tianshi Zhang, Yingqi Lu, Jinwei Shi, Lijuan Yang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Phosphate fertilizers are used in horticultural production to increase yields, but overuse can result in inefficient crop uptake and large loss of phosphorus (P). Soil amendments could potentially reduce the risk of P loss while maintaining high crop yield. The objective of this study was to investigate the effect of organic and inorganic amendments on P fractions in soils with different P levels (low, medium and high), and the underlying mechanisms. Five treatments were included: no amendment (CK), chemical fertilizers (CF), rice straw (FS), chicken manure compost (CM), and vermicompost (VM). Counterintuitively, the proportion of organic phosphorus (OP) tended to increase in the CF treatment, especially in soil with low P level. Results indicated that the change in the proportion of OP was mainly controlled by soil acid phosphomonoesterase, alkaline phosphomonoesterase and phosphate-solubilizing microorganisms. The proportion of available P increased in soil with low P level, but decreased in soil with high P level in the VM treatment. Non-labile P was preferentially formed in the VM treatment because of the high calcium content in vermicompost. Phosphates associated with aluminum (Al-P) were significantly higher in the CM treatment than in other treatments. This treatment also had a large presence of 〈em〉Pseudomonas〈/em〉 and 〈em〉Streptomyces〈/em〉 bacteria, which are capable of promoting the formation of Al-P. Our results indicated that mechanisms causing changes in soil P fractions were distinctly different among various amendments, and that vermicompost had the greatest potential to increase P supply in soil with low P level, and to decrease the risk of P loss in soil with high P level.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0341816218303424-ga1.jpg" width="422" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 172〈/p〉 〈p〉Author(s): Yoshinori Shinohara, Yuma Misumi, Tetsuya Kubota, Kazuki Nanko〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In Japan, moso-bamboo (〈em〉Phyllostachys edulis〈/em〉 (Carrière) J. Houz.), an invasive species, has spread into and replaced surrounding broadleaved and coniferous forests because of the inactive management of moso-bamboo forests. Some local governments in Japan have speculated about an increase in soil erosion caused by the replacement with moso-bamboo forests. To evaluate the impact of such replacement on soil erosion, the soil erosion rate in a moso-bamboo forest was compared with those in an evergreen broadleaved forest and a coniferous forest. We established three plots (width 1 m, length ca. 2 m) in each forest and measured overland flow and soil erosion in two continuous periods (Period I: July 26, 2012–April 26, 2013; Period II: April 26, 2013–July 17, 2014). In Period I, the soil erosion rate in the moso-bamboo forest (0.08–0.10 g m〈sup〉−2〈/sup〉 mm〈sup〉−1〈/sup〉) was not significantly higher than that in the broadleaved forest (0.27–0.55 g m〈sup〉−2〈/sup〉 mm〈sup〉−1〈/sup〉) and the coniferous forest (0.16–0.27 g m〈sup〉−2〈/sup〉 mm〈sup〉−1〈/sup〉). In Period II, we removed understory vegetation and litter from two of the three plots in each forest. In Period II, the plots with such removal had higher soil erosion rates than the control plots. The soil erosion rate for the removal plots of the moso-bamboo forest was less than half of those of the broadleaved and coniferous forests. Although rock fragment cover on the soil surface and shear strength of the topsoil did not differ significantly among the three forests, root density in the moso-bamboo forest was much greater than those in the broadleaved and coniferous forests. These results suggest that a large amount of roots in moso-bamboo forests could reduce soil erosion there. The findings of this study show that moso-bamboo forests have strong resistance against soil erosion, so the replacement of broadleaved and coniferous forests by moso-bamboo forests would not seem to imply an increase in soil erosion.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 173〈/p〉 〈p〉Author(s): Namratha Reddy, David M. Crohn〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Amending saline-sodic soils with organic manures and composts can help to remediate them by improving their physical, chemical, and biological properties. Little is known as to how temperature effects organically amended saline-sodic soils in terms of soil nitrogen (N) dynamics, greenhouse gases, and dinitrogen (N〈sub〉2〈/sub〉) emissions, however. The effects of soil temperature and organic matter applications to a saline-sodic soil on CO〈sub〉2〈/sub〉, N〈sub〉2〈/sub〉O, and N〈sub〉2〈/sub〉 emissions were investigated. An extreme saline-sodic soil with electrical conductivity (EC〈sub〉e〈/sub〉) 100 dS m〈sup〉−1〈/sup〉 and pH 7.8 was used in this study. Four organic amendment treatments were selected: active greenwaste (AGW), cured greenwaste compost (CGW), active dairy manure (ADM), and cured dairy manure compost (CDM). All treatments were incorporated at 100 Mg ha〈sup〉−1〈/sup〉 and incubated at 70% water-filled pore space (WFPS) for 60 days at 15, 25, and 35 °C. Relative to 15 °C emissions, increasing soil temperatures significantly enhanced cumulative CO〈sub〉2〈/sub〉, N〈sub〉2〈/sub〉O, and N〈sub〉2〈/sub〉 losses from all treatments. The emissions of CO〈sub〉2〈/sub〉 increased in the AGW and ADM by 1.5 to 2.2 fold compared to CGW and CDM amended soils at all three temperatures. Higher cumulative N〈sub〉2〈/sub〉O-N emissions were released from ADM compared to AGW and CDM compared to CGW treatments at 25 and 35 °C, respectively. At 25 and 35 °C, AGW and CDM increased N〈sub〉2〈/sub〉 emissions relative to ADM and CGW, respectively. It was found that soil temperature had a significant effect on CO〈sub〉2〈/sub〉, N〈sub〉2〈/sub〉O, and N〈sub〉2〈/sub〉 emissions. However, CO〈sub〉2〈/sub〉 production highly correlated with N〈sub〉2〈/sub〉 emissions indicating that active organic materials could be carefully applied to remediate saline-sodic soils while mitigating N〈sub〉2〈/sub〉O emissions.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 172〈/p〉 〈p〉Author(s): Mohamad Basel Al Sawaf, Kiyosi Kawanisi〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉To assess the dynamics of rivers, a reliable characterization of river streamflow during unsteady flow regimes is of paramount importance. In this work, we aimed at investigating the characteristics of turbidity–discharge (T–Q) dynamics corresponding to annual artificial dam flush release in a mountainous stream. Two methods for evaluating discharge were used in this study: the classical rating curve and the fluvial acoustic tomography (FAT) system that was developed by Hiroshima University. Interestingly, during dam flush, the discharge records obtained by FAT showed striking features of unsteady streamflow behavior, such as discharge shoulders and, in some events, secondary discharge peaks. According to the T–Q hysteresis loops, the common type of T–Q observed patterns were anticlockwise loops. During the studied DF events, sediment was supplied by river banks located at different sites along the river channel.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 172〈/p〉 〈p〉Author(s): Jie Du, Jianzhi Niu, Zhaoliang Gao, Xiongwen Chen, Linus Zhang, Xiang Li, Natalie S. van Doorn, Ziteng Luo, Zhijun Zhu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Rainfall interception and other hydrologic processes affected by the forest litter layer are usually related to litter characteristics and rainfall conditions, with limited studies that consider the influence of slope. To simulate the hydrological functions of the litter layer at different slope gradients, artificial rainfall experiments were conducted at four rainfall intensities (from 30 to 120 mm hr〈sup〉−1〈/sup〉) in horizontal and inclined trays (with the slope of 0°, 10°, 20° and 30°) with litter of 〈em〉Pinus tabuliformis〈/em〉 or 〈em〉Quercus variabilis〈/em〉. The results indicated that (1) the dynamic process of litter interception had 3 phases: a rapid intercepted phase within the first 5 min, a moderate intercepted phase and a post-rainfall drainage phase; (2) the maximum interception storage (〈em〉C〈/em〉〈sub〉max〈/sub〉) and the minimum interception storage (〈em〉C〈/em〉〈sub〉min〈/sub〉) of 〈em〉Q. variabilis〈/em〉 were larger than those of 〈em〉P. tabuliformis〈/em〉; (3) 〈em〉C〈/em〉〈sub〉max〈/sub〉 and 〈em〉C〈/em〉〈sub〉min〈/sub〉 were correlated with slope for both types of litter, whereas only 〈em〉C〈/em〉〈sub〉max〈/sub〉 was correlated with rainfall intensity; and (4) lateral flow amount significantly increased with both slope gradient and rainfall intensity only for 〈em〉Quercus variabilis〈/em〉, whereas drainage volume showed significant correlation with rainfall intensity. Moreover, the ratio of lateral runoff and drainage was affected by slope gradient whereas percentage of litter interception had a good relationship with rainfall intensity, rather than slope, with litter interception and drainage contributing the smallest and the largest proportions, respectively. Overall, the results demonstrate the effect of rainfall and slope factors on hydrological processes in the forest litter layer.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 172〈/p〉 〈p〉Author(s): Sri Rahayu Utami, Florias Mees, Mathijs Dumon, Nikolla P. Qafoku, Eric Van Ranst〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We studied the relationship between the mineralogical composition and surface charge properties of representative Quaternary volcanic ash soils, classified as Andosols, along an East-West sequence on Java Island in Indonesia. The soil charge characteristics were determined using ‘charge fingerprinting’ procedures. Most of the studied soils have a limited ability to retain cations under their forest or grass vegetation. The surface charge properties of these soils are mainly related to allophane and organic matter contents and, to a lesser degree, to ferrihydrite content and layer silicate characteristics. In East Java, the soils are Andosols with low allophane content, dominated either by halloysitic clays or by a mixture of 2:1 and 1:1 layer silicate clays; these soils are characterized by a low to moderate permanent charge. In West Java, the soils are rich in allophane, with subordinate kaolinitic clays, gibbsitic material or a mixture of 1:1 and 2:1 layer silicate clays; in contrast to the allophane-poor soils of East Java, these soils have extreme variable charge characteristics, creating a net ‘positive’ variable surface charge at soil pH. Differences in mineralogical composition of the clay fraction are attributed mainly to more pronounced seasonality in East Java, with variations in parent ash composition, becoming more acidic from east to west, as subordinate factor. The more severely leaching environment in West Java results in a higher degree of desilication, which led to a higher point of zero net charge (PZNC) and pHo in the allophane-rich soils. This study demonstrates how a climatic gradient can affect regional variations in charge properties, through the impact of climate on the mineralogical composition of the clay fraction. Regional patterns of this type must be understood to correctly assess of variations in soil fertility status and to make correct soil management choices for sustainable crop production.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0341816218303928-ga1.jpg" width="467" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 172〈/p〉 〈p〉Author(s): Xing Jian, Wei Zhang, Hanghai Liang, Ping Guan, Ling Fu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Weathering, as an important process in the earth surface system, can be significantly influenced by tectonics and climates over long time scales. Here, we use mineralogical, petrographic and geochemical data of a paleoweathering profile developed on basement granodioritic rocks of northern Qaidam basin, northern Tibet, to reconstruct early Eocene weathering conditions and to discuss how paleoclimates and tectonics dominated the weathering process. The results indicate that neoformed mineral phases in weathering products are dominated by smectite, and the profile has overwhelmingly low chemical index of alteration values (ca. 51–59) and significantly decreasing micropetrographic index values (from 25.0 to 0.2) from bottom to top. These findings suggest that the basement rocks experienced mild chemical weathering but relatively intensive physical weathering. We favor that non-steady-state weathering, in which mechanical erosion rates compare favorably with rates of chemical weathering, prevailed in northern Tibet during the early Eocene. The weathering conditions were likely an integrated response to active tectonism and dry climates at that time. Furthermore, chemical element mobility evaluation demonstrates that most of large ion lithophile elements and light rare earth elements (LREEs) of granodioritic rocks are quite active during weathering and can be easily leached even under mild chemical weathering conditions. Significant mass loss of Al and LREEs in upper weathered samples probably reflects acidic weathering conditions, which were likely due to extremely high atmospheric CO〈sub〉2〈/sub〉 level during the early Eocene. This study, from the unique perspective of weathering process, suggests that intensive deformation and rapid tectonic erosion occurred in northern Tibet during the early Eocene, as a far-field response to the India-Eurasia collision. It also agrees with warm and relatively dry climates, which were likely attributed to the global greenhouse climates and the Paleogene planetary-wind-dominant climate system in Asia, respectively.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 172〈/p〉 〈p〉Author(s): Weibo Kong, Yufei Yao, Zhongna Zhao, Xin Qin, Hansong Zhu, Xiaorong Wei, Mingan Shao, Zhao Wang, Kaiqiang Bao, Min Su〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The presence of vegetation has significant effects on soil nitrogen (N) turnover. However, whether these effects vary with slope aspect, vegetation type and time of season were not understood in previous studies, precluding our ability to understand how vegetation affects soil N cycling in sloping land. In this study, we investigated the effects of vegetation presence (plots with vs. without vegetation), vegetation type (grassland vs. woodland) and slope aspect (east vs. west slope) on soil N turnover during the growing season in sloping lands of the Loess Plateau, China. Soil metrics measured included concentrations of ammonium (NH〈sub〉4〈/sub〉〈sup〉+〈/sup〉), nitrate (NO〈sub〉3〈/sub〉〈sup〉−〈/sup〉) and total mineral N (Min-N) in soil solution and rates of ammonification (R〈sub〉a〈/sub〉), nitrification (R〈sub〉n〈/sub〉) and net N mineralization (R〈sub〉m〈/sub〉). We hypothesized that the presence of vegetation would deplete the soil Min-N pool and decrease R〈sub〉m〈/sub〉 and that these effects would be greater in east slopes and woodlands than in west slopes and grasslands. In partial support of these hypotheses, vegetation presence decreased soil Min-N concentration but did not affect R〈sub〉m〈/sub〉. NH〈sub〉4〈/sub〉〈sup〉+〈/sup〉 and NO〈sub〉3〈/sub〉〈sup〉−〈/sup〉 contributed similarly to Min-N, while R〈sub〉n〈/sub〉 dominated R〈sub〉m〈/sub〉. The effects of vegetation presence on soil mineral N and N mineralization varied with the time of the season but were not related to the vegetation type and slope aspect. The soil Min-N and R〈sub〉m〈/sub〉 were significantly higher in woodlands, east slopes and 0–10 cm depth than grasslands, west slopes and 10–20 cm depth, respectively. The R〈sub〉a〈/sub〉 and NH〈sub〉4〈/sub〉〈sup〉+〈/sup〉 increased, while the R〈sub〉n〈/sub〉, R〈sub〉m〈/sub〉, NO〈sub〉3〈/sub〉〈sup〉−〈/sup〉 and Min-N decreased with increasing soil moisture. These results indicated that soil Min-N and R〈sub〉m〈/sub〉 in the sloping lands of the Loess Plateau consistently respond to vegetation presence across slope aspect and vegetation type, and were regulated by soil moisture.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 172〈/p〉 〈p〉Author(s): Chaobo Zhang, Xia Zhou, Jing Jiang, Yang Wei, Juanjuan Ma, Paul D. Hallett〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Root tensile strength controls root reinforcement, but a range of factors including root moisture and diameter have such a large impact that it is difficult to make predictions. In this study, we measured how variable root moisture content affects the relationship between root diameter and root tensile strength of herbaceous plants. Fresh roots of two herbaceous plants, 〈em〉Heteropappus altaicus〈/em〉 and 〈em〉Poa sphondylodes〈/em〉 were divided into four groups: (i) saturated in water, (ii) kept fresh, (iii) or dried for 6 h or (iv) 12 h in air. Root diameter and mechanical failure under tension before and after the moisture treatment were measured. Tensile strength and tensile force of both species decreased linearly while mean root diameter increased linearly with increasing root moisture content. Root moisture content has a large impact on the variability of root tensile strength. This emphasizes the need to avoid desiccation during testing. In field impacts of soil water potential on root strength requires further study. We recommend soaking roots in water before testing to decrease this source of error.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 172〈/p〉 〈p〉Author(s): C. Di Stefano, V. Ferro〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉Calanchi, a type of Italian badlands created by a combination of water erosion processes and environmental constraints controlling their development, is a striking example of long-term landscape evolution. Sediment connectivity can be defined as the degree to which a system facilitates the fluxes of sediments through itself. The goal of this research is testing the use of simple morphometric variables for assessing sediment connectivity of calanchi landforms distinguishing between dendritic and parallel systems. For detecting the morphological characteristics controlling the sediment connectivity of calanchi basins, literature data (146 calanchi basins) and measurements carried out in two areas located in Sicily (Italy) (119 calanchi basins) were examined. Application of Hack's law to the investigated calanchi basins, carried out distinguishing between landforms with dendritic and parallel systems, demonstrated that a calanco basin with a dendritic system has an exponent (k = 0.49) which is close to that (k = 0.55–0.60) typical of a river basin. The analysis also showed that Melton number assumes only for calanchi basins with a dendritic system a value (0.648) which is similar to that of the river case (0.694). For establishing calanchi hillslope connectivity, the hillslope sediment transport efficiency was also measured by the travel time, which is the ratio between the length and the square root of the hillslope steepness of each cell of the calanchi DEM, and the corresponding sediment delivery ratio.〈/p〉 〈p〉The concept of sediment delivery ratio of each hillslope cell SDR〈sub〉i〈/sub〉 was used as a measure of sediment connectivity since low values of this ratio imply a lack of connectivity (structural and/or hydrological). For each calanco the cumulative frequency distribution of the travel time allowed both to test the applicability of the exponential relationship used in SEdiment Delivery Distributed (SEDD) model to calculate SDR〈sub〉i〈/sub〉 and to estimate the coefficient β appearing in this relationship. Finally, the median travel time and the sediment delivery ratio SDR〈sub〉M〈/sub〉 of each calanco basin were calculated to evaluate the structural connectivity at calanchi basin scale. The analysis demonstrated that both a dendritic system has median travel time values less than those of a parallel system and that SDR〈sub〉M〈/sub〉 values of a dendritic system are higher than those of a parallel one. In conclusion, sediment connectivity of a dendritic system is higher than that of a parallel one.〈/p〉 〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 172〈/p〉 〈p〉Author(s): Achenafi Teklay, Yihun T. Dile, Shimelis G. Setegn, Solomon S. Demissie, Dereje H. Asfaw〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Land Use Land Cover (LULC) change significantly affects hydrological processes. Several studies attempted to understand the effect of LULC change on biophysical processes; however, limited studies accounted dynamic nature of land use change. In this study, Soil and Water Assessment Tool (SWAT 2012) hydrological model and statistical analysis were applied to assess the impacts of land use change on hydrological responses such as surface runoff, evapotranspiration, and peak flow in Gummara watershed, Ethiopia. Moreover, the effects of static and dynamic land use data application on the SWAT model performance were evaluated. Two model setups, Static Land Use (SLU) and Dynamic Land Use (DLU), were studied to investigate the effects of accounting dynamic land use on hydrological responses. Both SLU and DLU model setups used the same meteorological, soil, and DEM data, but different land use. The SLU setup used the 1985 land use layer, whereas the DLU setup used 1985, 1995, 2005, and 2015 land use data. The calibration (validation) results showed that the model satisfactorily predicts temporal variation and peak streamflow with Nash Sutcliffe Efficiency (NSE) of 0.75 (0.71) and 0.73 (0.71) in the DLU and SLU setups, respectively. However, the DLU model setup simulated the detailed biophysical processes better during the calibration period. Both model setups equally predicted daily streamflow during the validation period. Better performance was obtained while applying the DLU model setup because of improved representation of the dynamic watershed characteristics such as curve number (CN2), overland Manning's (OV_N), and canopy storage (CANMX). Expansion of agricultural land use by 11.1% and the reduction of forest cover by 2.3% during the period from 1985 to 2015 increased the average annual surface runoff and peak flow by 11.6 mm and 2.4 m〈sup〉3〈/sup〉/s, respectively and decreased the evapotranspiration by 5.3 mm. On the other hand, expansion of shrubland by 1% decreased the surface runoff by 1.2 mm and increased the evapotranspiration by 1.1 mm. The results showed that accounting DLU into the SWAT model simulation leads to a more realistic representation of temporal land use changes, thereby improving the accuracy of temporal and spatial hydrological processes estimation.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 172〈/p〉 〈p〉Author(s): Andrzej Walega, Tomasz Salata〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The aim of this work was to assess the accuracy of direct runoff depth calculated according to an original 〈em〉Soil Conservation Service〈/em〉 – 〈em〉Curve Number〈/em〉 (SCS-CN) method and a modified 〈em〉Sahu〈/em〉-〈em〉Mishra〈/em〉-〈em〉Eldho〈/em〉 (SME) method based on different sources of information on land cover. Main novelty of this work is using 〈em〉Database of topographic objects〈/em〉 (BDOT10k) instead of 〈em〉Corine Land Cover〈/em〉 (CLC) for the assessment of land cover in a catchment. The research was performed in the Kamienica river, a right tributary of the Dunajec, Poland. The effect of land cover data on runoff depth was assessed with the original SCS-CN method, and modified SME method. The value of 〈em〉CN〈/em〉 parameter was estimated using two databases on land use, CLC and BDOT10k. BDOT10k was proven to be a considerably more precise land cover database that enabled more accurate interpretation. The study demonstrated the highest accuracy of direct runoff calculation with SME-CN method, irrespective of the approach used for determination of the catchment land use. The use of SME-CN instead of the original SCS-CN method provides much more accurate prediction of direct runoff in a catchment.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 172〈/p〉 〈p〉Author(s): S.B. Mwango, J. Wickama, B.M. Msanya, D.N. Kimaro, J.D. Mbogoni, J.L. Meliyo〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Soil organic carbon (OC) plays a vital role on physico-chemical and biological properties of soils and on climate change regulation. The use of pedo-transfer functions from easily available soil properties for estimating soil OC could be fast and cheap when considering field and laboratory work implications especially in Sub Saharan Africa including Tanzania. This paper attempts to develop a model for estimating soil OC contents under maize croplands ecosystem using pedo-transfer functions from soil texture. A total of 100 epipedon data entries were randomly collected from the previous soil sampling works that were conducted under maize croplands in coastal plains of Tanzania. Eighty percent of the collected data were used for training the model by using multiple regression analysis while the remained 20% were used to validate the model. The results indicated that, clay and silt had significant (〈em〉p〈/em〉 〈 0.001) positive correlation with soil OC while sand contents in soils had negative (〈em〉p〈/em〉 〈 0.001) correlation with soil OC. All together clay, sand and silt were revealed powerful predictors (〈em〉p〈/em〉 〈 0.001, R〈sup〉2〈/sup〉 = 0.82) of OC content in soils. On validation, the soil OC predicted agreed by 81.2% with the soil OC determined by laboratory test. These results imply that pedo-transfer functions for predicting soil OC based on soil texture is not only fast and cheap but also is an effective option for estimating OC content in soils.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 173〈/p〉 〈p〉Author(s): Kai Li, Dongxia Yue, Jianjun Guo, Fan Jiang, Jianjun Zeng, Mingliang Zou, Eduardo Segarra〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Geohazards often cause a lot of damage to human life and property. Among the geohazard mitigation measures, ecological restoration engineering is an ecomonic and widely-used one, but the effectiveness varies with the alternatives' settings and the local stand conditions, and there is a lack of effective means to assess it. The objective of this paper is to evaluate the effectiveness of vegetation restoration alternatives on mitigating geohazards in Bailong River Basin (BRB), where the soil erosion and debris flow are very severe. Given the significance of surface hydrological process in the formation of geohazards, the surface runoff depth (SRD) simulated by the Soil and Water Assessment Tool (SWAT) was chosen to evaluate the effectiveness of the mitigation alternatives. We designed four groups of ecological restoration scenarios, among which the first three groups returned the cropland with slope above 0, 15 and 25°, respectively, to one type of vegetation from evergreen forest, deciduous forest, mingled forest, shrub and grassland. The fourth group returned two slope levels of cropland to combination of two from the above five vegetation types. At the basin level, it was shown that all the alternatives could reduce the SRD. The evergreen forest alternative performs better than other vegetation types, and converting cropland above 15° is more efficient than converting cropland above 0 and 25°. The combination of evergreen and shrub in group 4 reduces SRD the most. At the subbasin level, the spatial heterogeneity of restoration alternatives effectiveness was shown. The reduction rate of SRD at the subbasin level reveals that the restoration measures would perform well in the northeastern basin and the eastern area of midstream. The reduction of SRD per unit returned cropland area reveals that the efficiency of reducing more SRD with less returned cropland is higher in the northeastern basin. Further, a map of most efficient group 4 scenarios at the subbasin level is obtained. Our work is expected to provide information regarding the establishment or improvement of ecological restoration policy in mitigating geohazards.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S034181621830403X-ga1.jpg" width="500" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 172〈/p〉 〈p〉Author(s): Theresa Bonatotzky, Franz Ottner, Egill Erlendsson, Guðrún Gísladóttir〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉Little is known about the impact of tephra deposits from explosive volcanic eruptions on soil formation and weathering processes in organic soils. The weathering of tephra of basaltic and rhyolitic origin and their impact on Icelandic histosols were studied through a combination of physical, chemical and mineralogical analyses. Two sampling sites were selected according to the presence of the light coloured rhyolitic tephra from the Öræfajökull eruption in 1362 CE and a dark-coloured basaltic Veiðivötn tephra from 1477 CE in the volcanically active area south of Vatnajökull in South East Iceland.〈/p〉 〈p〉The determining factor of pedogenesis in the investigated histosols is the OM, but the influence of tephra and aeolian material from external sources must be taken into consideration. The soils are the result of altered plant residues and volcanic material (tephra and aeolian material). Plant remnants, as well as the soil itself, are protected from decomposition by the prevailing anaerobic conditions, a low soil pH and the repeated addition of inorganic matter. Clay formation is low, while metal-humus complexes are predominant. Fe〈sub〉o〈/sub〉/Fe〈sub〉d〈/sub〉 ratios indicated a generally low degree of weathering, being higher close to the basaltic tephra.〈/p〉 〈p〉The mineralogy was dominated by plagioclase and pyroxene, with quartz and zeolite as minor components. In contrast to previous research on Icelandic soils, our investigations revealed layer silicates at both sites. While we found evidence of smectite in the soils at Kálfafell, hydroxy interlayered minerals were found at Reynivellir. In the basaltic tephra, traces of layer silicates could be verified. In contrast, the rhyolitic tephra did not show any pedogenic minerals, suggesting that it had hardly altered since its deposition in 1362 CE. It is not the chemical composition of the inorganic parent material, but the location that may be an influencing factor on the formation of clay minerals in the investigated histosols.〈/p〉 〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 172〈/p〉 〈p〉Author(s): Lúcio Fábio Lourençato, Marcelo Corrêa Bernardes, Andressa Cristhy Buch, Emmanoel Vieira Silva-Filho〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Tropical peatlands are very different from boreal and temperate regions, because they have particular climatic characteristics and different vegetation types. Similarly, high mountain peatlands differ significantly from those found at low altitudes. Lignin components were investigated as phyto-physiological proxies of landscape evolution in two big national environmental conservation parks of Southeastern Brazil. Lignin phenols showed a high degree of humification and indicated the same land-use for both forest parks, suggesting minimal anthropic intervention over the last 150 years, predominating native grasslands. However, total organic carbon (TOC) and total nitrogen (TN) parameters evidenced the influence of indirect effects of human activities, mainly from atmospheric deposition since 1950s, associated to the early Brazilian industrial development. This study reinforces the importance of protection and conservation to those pristine areas.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0341816218303813-ga1.jpg" width="301" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 172〈/p〉 〈p〉Author(s): David Martín-Perea, Omid Fesharaki, M. Soledad Domingo, Sara Gamboa, Manuel Hernández Fernández〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉Few studies have inquired about the relationship between myrmecological activity and the granulometry and mineralogy of sediments of a palaeontological site. The objectives of this article are to determine the sedimentological or mineralogical distinctions produced by ants of the species 〈em〉Messor barbarus〈/em〉 when excavating their nests and extracting grains and vertebrate fossil remains from the Miocene palaeontological site of Somosaguas (Madrid, Spain), to evaluate the degree of taphonomic influence this myrmecological activity has on the fossil remains, and to decide whether or not it can be used as a tool for palaeontological prospection. Results show that 〈em〉Messor barbarus〈/em〉 does not alter fossil remains when examined under a 10× binocular magnifying glass. Ants preferentially extract from the ant nest grains of medium sizes (0.25–2 mm) compared to the non-ant-modified soils, and also extract a higher quantity of feldspars. These significant granulometric and mineralogical modifications should be considered when carrying out compositional, sedimentological or stratigraphical studies, since these can become biased and alter geological interpretations as provenance or palaeoclimatic signal. Grain size selection could be due to 〈em〉Messor barbarus〈/em〉' physical capacities or the use of clay particles as cementing elements in nests. Mineralogical distinction may be related to feldspars' embayments and pits filled with finer material (mainly smectites), making transportation and pheromone impregnation easier.〈/p〉 〈p〉Results show that the ant mounds had increasing concentrations of fossil remains the nearer they were from the main excavation area, therefore the study of ant mounds in potentially fossiliferous zones can indeed be used as a new method of palaeontological prospection.〈/p〉 〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 172〈/p〉 〈p〉Author(s): P.G. Panin, S.N. Timireva, E.A. Konstantinov, P.I. Kalinin, Yu.M. Kononov, A.O. Alekseev, V.V. Semenov〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The loess-paleosol sequence exposed in the Beregovoye section (southwest of the Crimean Peninsula) has been thoroughly studied. Detailed analysis of the paleosol morphology, physical properties and chemical composition, micromorphology and other characteristics made it possible to identify types of paleosols formed in the Pliocene and Pleistocene. The results obtained gave us an insight into the climate and environments of the past. According to them, the climate of the Pliocene optimum was extremely hot and wet, and the soil zonality was hardly pronounced practically over entire Central and Eastern Europe. At the final phase of the Pliocene the climate became drier, though the rainfall amount was still greater than in the Holocene. During the Early Pleistocene the soil development followed the Mediterranean type, the climate being still warm, though less humid than in the Pliocene. There are two peaks of catastrophic changes in the evolution of the climate and environments distinctly traceable in the Beregovoye section: first – corresponding to the global change recorded between the Pliocene and Pleistocene and second, falling on the initial phase of the modern (Holocene) soil formation.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 172〈/p〉 〈p〉Author(s): Youxin Shen, Dianjie Wang, Qiaoqiao Chen, Yingyin Tang, Fajun Chen〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Rock outcrops are frequently visible in terrestrial landscapes, typically in karst. However, there has been insufficient research conducted on their effects on the formation of soil water and nutrients heterogeneity in nearby soil patches. In: 1) a rock desertification ecosystem, 2) an anthropogenic forest ecosystem, and 3) a secondary forest ecosystem in Shilin, Southwest China, rock occupancy ratio was measured, water received by and subsequently funneled off by rock outcrops was quantified, and their concentrations of the total organic carbon, nitrogen, phosphorus, and potassium were determined. Receiving rate R〈sub〉r〈/sub〉 of those elements of the remaining soil patches in various 2 m × 2 m soil + rock outcrop samples were calculated, and r〈sub〉200〈/sub〉 at which R〈sub〉r〈/sub〉 of the remaining soil patch was twice that without rock emergence was calculated to evaluate the heterogeneity difference among different elements in different ecosystems. There were 1.43–5.44 folds differences between R〈sub〉r〈/sub〉 under the highest rock ratio (79.4%) sample and the rate of non-rock emergence sample for water, organic carbon, nitrogen, phosphorus, and potassium in the three ecosystems respectively, indicating a large supply heterogeneity for those elements within an ecosystem and between ecosystems. The r〈sub〉200〈/sub〉 were between 47% (water, at rock desertification ecosystem) to 90% (potassium at rock desertification ecosystem, depending on the receiving rate and funneling rate of the rock for different element in different ecosystem. In conclusion, large supply heterogeneity has derived from high variation of rock runoff determined by rock emergency ratio, the rate of receiving and the rate of funneling off by the rock. Our study provided new evidence to trace soil and water heterogeneity of microhabitats in rocky ecosystems. Additionally, rock outcrop is also an important factor in evaluating hydrological and related nutrient characteristics in rocky ecosystems.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 172〈/p〉 〈p〉Author(s): Zhiwei Li, Peng Gao〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Neck cutoff is an essential process that significantly changes the morphodynamic characteristics of a meandering bend. In reality, however, observing natural processes of a neck cutoff is very difficult. In this study, we artificially triggered neck cutoffs by excavating a 0.4 m (width) × 0.5 m (depth) ditch to connect the beginning and ending of two highly convoluted bends along a meandering tributary of the upper Black River, a major tributary of the Upper Yellow River situated in the northeastern side of the Qinghai-Tibet Plateau in China. Our morphologic and hydraulic measurements in summers of 2013, 2014, 2016, and 2017, the subsequent hydraulic-geometry analysis, and three-dimensional simulation showed that both artificial ditches expanded fast to the size comparable to the former channel in a three-year period and the oxbow channel was disconnected from the former channel quickly, though sediment supply may be limited in this area. The morphological adjustment was featured by (1) distinct temporal trends of the development of the width/depth ratio between the two cutoff channels, (2) different diversion factors of the total discharge to the cutoff channel, and (3) diverse interaction patterns between cutoff and former channels. These discrepancies were supported by simulated different three-dimensional velocity distributions in the two cutoff channels, suggesting the importance of the clustered local velocities. Comparing these results with those reported in earlier studies showed that besides channel slope, unit stream power, and bank strength, the diversion angle between the cutoff and former channel played an important role in controlling channel adjustment. The discrepancy of the adjustment processes between the cutoff channel in this study and those in two previous ones revealed that channel adjustment after neck cutoff behaved differently under different physical settings and require more field-based studies.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 172〈/p〉 〈p〉Author(s): Mikel Goñi, J. Javier López, Faustino N. Gimena〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Two variants of the Instantaneous Unit Hydrograph model based on a Geomorphological association of linear Reservoirs (IUHGR), incorporating the Spatial Variability of Rainfall (SVR), have been developed. The proposed models are based on the Geomorphological Reservoirs (GR) scheme consisting of a cascade of linear reservoirs aggregating sub-watersheds. The model, in its first version, was formulated so that it incorporated a spatial variability pattern of rainfall associated with a certain frequency and oriented towards its application in the field of hydrological design. This model was considered to be stationary in the time (GRSVR(s)) for being linked to some design conditions. The second version of the model is applicable to the simulation of real events, where there is a dynamic (GRSVR(m)) spatial distribution of rainfall that varies in time, as in the case of the movement of rainstorms. Both models permit the input of relevant information on the spatial variability of the rainfall, taken from different rain gauge records, without losing the simplicity of the GR model with a single parameter, which represents the hydrological time response of the watershed. The models have been calibrated and validated with the data from one gauged watershed in northern Spain. The analysis conducted in both cases showed that the models which contemplated the spatial variability of the rainfall, GRSVR(s) and GRSVR(m), were capable of simulating rainfall variability effects in the surface runoff hydrograph better than the GR model, which averages the precipitation values recorded in the different rain gauges.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 172〈/p〉 〈p〉Author(s): Flavia Tauro, Rodolfo Piscopia, Salvatore Grimaldi〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Particle tracking velocimetry (PTV) is a promising image-based approach for remote streamflow measurements in natural environments. However, most PTV approaches require highly-defined round-shaped tracers, which are often difficult to observe outdoors. PTV-Stream offers a versatile alternative to cross-correlation-based PTV by affording the identification and tracking of features of any shape transiting in the field of view. This nearest-neighbor algorithm is inherently thought for estimating surface flow velocity of streams in outdoor conditions. The procedure allows for reconstructing and filtering the trajectories of features that are more likely to pertain to actual objects transiting in the field of view rather than to water reflections. The procedure is computationally efficient and is demonstrated to yield accurate measurements even in case of downsampled image sequences.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 173〈/p〉 〈p〉Author(s): Xiaobing Zhou, Xiangfang Lv, Ye Tao, Lin Wu, Caroline A. Havrilla, Yuanming Zhang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Desert ecosystems are nitrogen-limited, and highly responsive to even small inputs of nitrogen. Recently, desert ecosystems have been affected by increasing levels of nitrogen deposition, which may lead to changes in greenhouse gas efflux. However, the effects of nitrogen deposition on these gases in the desert ecosystems remain poorly understood. To study the dynamics in greenhouse gases under increasing nitrogen, six rates of simulated nitrogen deposition, including 0(N0), 0.5(N0.5), 1.0(N1), 3.0(N3), 6.0(N6), 24.0 (N24) g nitrogen m〈sup〉−2〈/sup〉 a〈sup〉−1〈/sup〉, were applied in soils of the Gurbantunggut Desert in Central Asia. Efflux of nitrous oxide (N〈sub〉2〈/sub〉O), methane (CH〈sub〉4〈/sub〉), ecosystem respiration and net carbon ecosystem exchange were measured across two growing seasons for two years. The efflux of the four gases changed greatly in different seasons, which can explain more variation than nitrogen treatments except for N〈sub〉2〈/sub〉O. Nitrogen input stimulated N〈sub〉2〈/sub〉O emission, especially in the high nitrogen treatments, with N〈sub〉2〈/sub〉O emission 1.6 (N6) and 2.6 (N24) times greater than control (N0). However, N〈sub〉2〈/sub〉O exchange also depended on the seasons, while only minor changes were found in some seasons (late spring 2010 and late summer 2011). Overall, CH〈sub〉4〈/sub〉 uptake (average 31.4 μg m〈sup〉−2〈/sup〉 h〈sup〉−1〈/sup〉) was not significantly affected by the nitrogen addition. At the high nitrogen treatment levels, ecosystem respiration decreased in the late spring and summer of the second year, with similar responses to nitrogen addition in mid-autumn between two years. Net ecosystem carbon exchange also showed gradual responses to nitrogen addition overall, but did not differ significantly across seasons and treatments. Overall, structural equation models showed that the dynamics in N〈sub〉2〈/sub〉O were mostly attributed to variations in nitrogen addition, CH〈sub〉4〈/sub〉 to soil moisture (or temperature), ecosystem respiration to plant species richness (or density) and net ecosystem carbon exchange to soil moisture (or temperature). Our study indicates that the changes in greenhouse gas emissions caused by nitrogen deposition in short time scale were small in these desert soils.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 172〈/p〉 〈p〉Author(s): Sayahnya Roy, Vikas Kumar Das, Koustuv Debnath〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The complex interplay between the resistive forces of the bank material and Reynolds shear stress of the turbulent flow field control the fluvial bank erosion. In-depth knowledge on the interactions of the flow-form at the river bank is a prerequisite to understand erosion mechanism and quantification of the erosion rate. Measurement at 1.5 m from the bank face as reported in the literature revealed that turbulent lateral flux of stream-wise momentum propagated towards the bank face that was held responsible for the removal of material from the bank face. Further experimental results from the literature depict that the stream-wise and lateral fluctuating velocity components deploy a random forcing effect on the river bank face which may be one of the primary agents for sediment particle entrainment from the bank face. It is gestated from these previous studies that the momentum flux and turbulent structures of the flow field has a great impact on the river bank erosion. Nevertheless, the previous field and experimental studies do not focus on the flow turbulence and sediment interaction that extracts information on the detailed temporal features of sediment entrainment process. Thus, the present study was carried out to understand the coupled dynamics of the effect of intermittent flow structures on the intermittent removal of river bank materials, and for advancing the knowledge on river bank erosion process. The present experimental study focuses on the evaluation of the turbulent flow characteristics when the undercut mechanism initiates in a cohesive river bank. Based on the results it is evident that moderate scale intermittent stream-wise flow structures probably imposes a periodic loading on the cohesive aggregates of the bank face. This accelerates the entrainment of aggregates from the bank face. The study also reveals that the undercut increment is a small scale intermittent process. Findings of the present study may be helpful for the improved design of bank protection measures.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 172〈/p〉 〈p〉Author(s): Ali Mutar Fanos, Biswajeet Pradhan〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Rockfall hazards occur widely in regions with steep terrain such as Kinta Valley, Malaysia. Rockfalls threaten urban areas and the transportation corridors that pass through such areas. This paper proposes a comprehensive rockfall hazard assessment strategy based on high-resolution laser scanning data (LiDAR), both airborne and terrestrial. It provides (1) rockfall source identification by developing a hybrid model based on a bagging neural network (BBNN), which is compared with various machine learning algorithms and ensemble models (bagging, boosting, voting) and a Gaussian mixture model; (2) 3D modelling of rockfall kinematic processes (trajectory distribution, frequency, velocity, kinetic energy, bounce height, impact location); and (3) hazard zonation based on spatial modelling in combination with an analytical hierarchy process (AHP) in a geographic information system (GIS). In addition, mitigation measures are suggested based on the modelling results. The proposed methodology was validated in three study areas to test the applicability and generalisability of the methods. The results show that the proposed hybrid model can accurately identify rockfall source areas at the regional scale. It achieved a 97% training accuracy and 5-fold cross-validation area under curve (AUC) value of 0.96. The mechanical parameters of the developed 3D model were calibrated with an accuracy of 97%, 93% and 95% for Gunung Lang, Gua Tambun and Gunung Rapat areas, respectively. In addition, the proposed spatial model effectively delineates areas at risk of rockfalls. This method provides a comprehensive understanding of rockfall hazards that can assist authorities to develop proper management and protection of urban areas and transportation corridors.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0341816218303801-ga1.jpg" width="405" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 172〈/p〉 〈p〉Author(s): Jun Wang, Huan Deng, Shao-Song Wu, Yong-Cui Deng, Li Liu, Cheng Han, Yun-Bin Jiang, Wen-Hui Zhong〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Soil exoelectrogenic bacteria have been found to perform various functions. However, little is known about whether exoelectrogenic bacteria are widely distributed in soil and which physico-chemical properties of soil significantly affect their distribution? To address the research questions, 37 soil samples covering six land use types, including arid farmland soils, woodland soils, grassland soils, paddy soils, lakeshore soils, and coastal soils were collected. DNA was extracted from all the samples for quantitative PCR and high throughput sequencing of the 16S rRNA gene. The sequencing result showed a total of 16 exoelectrogenic bacteria-associated genera from different soils. The total abundance of these genera varied from 1.14 × 10〈sup〉8〈/sup〉 copies g〈sup〉−1〈/sup〉 in a farmland soil to 7.89 × 10〈sup〉9〈/sup〉 copies g〈sup〉−1〈/sup〉 in a coastal soil, accounting for 0.26% to 7.70% of the total bacteria. Among the 16 genera, 〈em〉Bacillus〈/em〉 was dominant in the arid land soils, including the farmland, woodland, and grassland soils. The coastal soils were dominated by 〈em〉Desulfobulbus〈/em〉 whereas the paddy and lakeshore soils were characterized by abundant 〈em〉Geobacter〈/em〉. Principal component analysis showed a distinct separation of the exoelectrogenic bacterial community between the arid land (farmland, woodland, and grassland soils), freshwater wetland (paddy and lakeshore soils), and coastal soils. Redundancy analysis revealed that the water content, electrical conductivity and concentrations of total sulphur and amorphous Fe in the soil were significant factors driving the community structure and abundance of exoelectrogenic bacteria-associated genera. Our results should help in better understanding of the exoelectrogenic bacteria-mediated functions in soil, which might contribute to the biogeochemical cycling of a large number of organic and inorganic materials.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 172〈/p〉 〈p〉Author(s): M. Antonellini, B.M.S. Giambastiani, N. Greggio, L. Bonzi, L. Calabrese, P. Luciani, L. Perini, P. Severi〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We identified the processes governing natural land subsidence in a shallow coastal aquifer near Ravenna (North eastern Italy) by analysing the relationships among different data set time series (water table level, rainfall, drainage, sea level, etc.) and establishing the correlations with vertical ground motion observed at a high-resolution settlement gauge. For the first time we establish the relationships between water table fluctuations and vertical displacement in a real field dataset as well as demonstrate the important contribution of primary consolidation and aquifer stratigraphy to natural land subsidence. Our study highlights the presence of three deformation components related to different processes controlling land subsidence: elastic, delayed-elastic, and irreversible (plastic) components. The elastic and delayed-elastic components are closely related to water table fluctuations that change the effective stress in two portions of the coastal aquifer at a daily (in the sandy unconfined portion) and seasonal time scales (in the finely layered clay-rich semiconfined prodelta portion), respectively. The irreversible component represents the trend in the land subsidence time series and is due to primary consolidation (pore water pressure dissipation) of the fine-grained prodelta levels above where the settlement gauge is located. The amplitudes of the elastic component can be up to 0.2–0.3 mm whereas the amplitude of the delayed-elastic component reaches 0.89 mm. The primary consolidation rate of deformation is 0.9 mm/year and constrains the likely age of prodelta sediments deposition to 1300–2800 years before present. The average degree of consolidation for the prodelta sediments varies from 0.8 to 0.99 according to consolidation coefficients varying from 1.58 to 3.15 m〈sup〉2〈/sup〉/year, which are accepted values in the literature. Our analysis point out that primary consolidation in the shallow fine-grained sediments of the shallow coastal aquifer is still ongoing. The delayed-elastic land subsidence rate has similar magnitude to that due to primary consolidation and is likely connected to poroelastic effects in the prodelta sequence following seasonal variations in water table. Our findings are important for planning land subsidence management and monitoring strategies especially where the surface aquifer structure is heterogeneous due to different depositional settings.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 172〈/p〉 〈p〉Author(s): Cristina Fernández, Teresa Fontúrbel, José A. Vega〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Thousands of hectares of conifer plantations are affected every year by wildfire and subsequent erosion in the Mediterranean region. However, little is known about how post-fire erosion is influenced by the mechanical site preparation (MSP) techniques used at plantation establishment. Such information is needed for planning further reforestation, for reducing the hydrological impact of wildfire and subsequent soil degradation, and for favouring the natural resilience of perturbed ecosystems. Here we present a study conducted in NW Spain to evaluate how two MSP techniques commonly used at plantation establishment- hole planting and contour rip-plowing-, affected post-wildfire soil erosion and some edaphic properties (carbon content, penetration resistance, bulk density and aggregate stability) compared to the absence of intervention. The possible relationships between the soil properties and post-fire soil erosion were also examined. Finally, the effectiveness of erosion barriers, installed in burned sites originally established by hole planting and contour rip-plowing was evaluated. At the end of the two-year long study period, the accumulated soil loss was significantly lower in the contour rip-plowing treatment (0.7 Mg ha〈sup〉−1〈/sup〉) than in the hole planting treatment (6.7 Mg ha〈sup〉−1〈/sup〉) and the no intervention treatment (4.9 Mg ha〈sup〉−1〈/sup〉), but did not differ in the latter two treatments. Erosion barriers did not reduce post-fire soil erosion, which varied from 2.1 Mg ha〈sup〉−1〈/sup〉 in the contour rip-plowing + erosion barriers treatment to 8.3 Mg ha〈sup〉−1〈/sup〉 in the hole planting + erosion barriers treatment. Soil loss was related to soil burn severity. No significant relationship was observed between sediment production and any of the soil properties considered. The recovery of vegetation cover was not affected by the site preparation technique used. The study findings can be applied to reforestation planning and post-fire emergency stabilization actions.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 172〈/p〉 〈p〉Author(s): Jürgen Kern, Luise Giani, Wenceslau Teixeira, Giacomo Lanza, Bruno Glaser〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Historical land use and soil management left behind anthropic soils such as Amazonian Dark Earths (Terras Pretas de Índio - pretic Anthrosols), Anthropic shell mounds (Sambaquis - terric Anthrosols), and Plaggen soils (plaggic Anthrosols), enriched in soil organic matter and soil fertility. The objective of this study was to compare soil organic matter quantity and quality of these tropical and temperate anthropic soils among each other and against their adjacent non-anthropic soils. All anthropic soil horizons had enhanced total contents of C, N, P, K, Ca, Mg and Fe, reflecting a soil organic matter and nutrient enrichment compared to their reference soils, mostly expressed by the Sambaquis. In order to better understand the mechanisms of soil organic matter stability, besides black carbon analysis, topsoils and subsoils were incubated in the laboratory at 10 °C and 30 °C and the emitted CO〈sub〉2〈/sub〉 was recorded for 44-days. The Plaggen soil released the highest amount of CO〈sub〉2〈/sub〉 at 30 °C, being two to three times higher compared to Terra Preta de Índio and Sambaqui anthropic horizons. The highest mean residence times (MRT), between 38 and 63 years, were calculated for the subsoils of the anthropic soils incubated at 10 °C. In the artificial system of this study, the stability of anthropic soil horizons under study was not generally enhanced when compared with their reference soils. However, enhanced stability of total organic carbon (TOC) was indicated by a negative relationship between black carbon portion of TOC and the relative amount of CO〈sub〉2〈/sub〉-C released from TOC of all anthropic soils. During the incubation period of 44 days, the cumulatively mineralized amount of soil organic carbon (SOC) in the top of anthropic soils at 30 °C was three to six times as high as that at 10 °C. Consequently high temperature under tropical conditions should have stimulated the decay of organic matter, which however was not reflected by high TOC contents found in Terra Preta and Sambaqui samples, corroborating their low degradability in the long term. Therefore, we propagate that a high stability of carbon stocks exists in anthropic soil horizons, which may become a promising opportunity for the establishment of a new generation of anthropic soils with improved soil fertility and soil organic matter using the principle of soil-biochar systems.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 172〈/p〉 〈p〉Author(s): Wei Chen, Mahdi Panahi, Paraskevas Tsangaratos, Himan Shahabi, Ioanna Ilia, Somayeh Panahi, Shaojun Li, Abolfazl Jaafari, Baharin Bin Ahmad〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The main objective of the present study was to produce a novel ensemble data mining technique that involves an adaptive neuro-fuzzy inference system (ANFIS) optimized by Shuffled Frog Leaping Algorithm (SFLA) and Particle Swarm Optimization (PSO) for spatial modeling of landslide susceptibility. Step-wise Assessment Ratio Analysis (SWARA) was utilized for the evaluation of the relation between landslides and landslide-related factors providing ANFIS with the necessary weighting values. The developed methods were applied in Langao County, Shaanxi Province, China. Eighteen factors were selected based on the experience gained from studying landslide phenomena, the local geo-environmental conditions as well as the availability of data, namely; elevation, slope aspect, slope angle, profile curvature, plan curvature, sediment transport index, stream power index, topographic wetness index, land use, normalized difference vegetation index, rainfall, lithology, distance to faults, fault density, distance to roads, road density, distance to rivers and river density. A total of 288 landslides were identified after analyzing previous technical surveys, airborne imagery and conducting field surveys. Also, 288 non-landslide areas were identified with the usage of Google Earth imagery and the analysis of a digital elevation model. The two datasets were merged and later divided into two subsets, training and testing, based on a random selection scheme. The produced landslide susceptibility maps were evaluated by the receiving operating characteristic and the area under the success and predictive rate curves (AUC). The results showed that AUC based on the training and testing dataset was similar and equal to 0.89. However, the processing time during the training and implementation phase was considerable different. SWARA-ANFIS-PSO appeared six times faster in respect to the processing time achieved by SWARA-ANFIS-SFLA. The proposed novel approach, which combines expert knowledge, neuro-fuzzy inference systems and evolutionary algorithms, can be applied for land use planning and spatial modeling of landslide susceptibility.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0341816218303497-ga1.jpg" width="301" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 172〈/p〉 〈p〉Author(s): Lijuan Chen, Changsheng Li, Qi Feng, Yongping Wei, Yan Zhao, Meng Zhu, Ravinesh C. Deo〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The characteristics of ions in irrigation water can be significantly different in response to the changes in the salinity gradient. The chemical and biological processes of soils which were irrigated with this kind of water would therefore, be remarkably influenced. Based on the field sampling data and utilizing the Structural Equation Model (SEM), this paper aims to investigate the ionic characteristics of irrigation water and evaluate their direct and indirect impacts on soil salt ions, nutrients and microbial metabolic activities. The present results demonstrated that the ionic components of irrigation water had a direct influence on the soil salt ions. In particular, the Na〈sup〉+〈/sup〉 concentrations in irrigation water were not only seen to significantly increase the soil Na〈sup〉+〈/sup〉 concentrations but also change the other soil ions' concentrations. The contents of soil total nitrogen (TN), available phosphorus (P〈sub〉ava〈/sub〉) and available potassium (K〈sub〉ava〈/sub〉) appeared to change slightly with the increase of water salinity and meanwhile, no significant impact was found from any of the ions present in the irrigation water. Although high concentrations of Na〈sup〉+〈/sup〉, Cl〈sup〉−〈/sup〉, SO〈sub〉4〈/sub〉〈sup〉2−〈/sup〉, Mg〈sup〉2+〈/sup〉 and Ca〈sup〉2+〈/sup〉 in irrigation water significantly drove the reduction of the soil organic carbon (OC), the direct influences were actually relatively small in this respect, and it was the increase of soil salt ions that dominantly led this reduction. Irrigation water with high salinity contents could significantly restrain the soil microbial metabolic activities. In addition, high concentrations of SO〈sub〉4〈/sub〉〈sup〉2−〈/sup〉, Mg〈sup〉2+〈/sup〉, Cl〈sup〉−〈/sup〉, Ca〈sup〉2+〈/sup〉 and Na〈sup〉+〈/sup〉 in irrigation water (accounting for about 11% of the total effects), increased concentrations of soil salt ions (i.e., 74%) and reduced contents of soil OC (i.e., 15%) all contributed to this restraint, which together were seen to affect the microbial processes under saline water irrigation. The present results revealed that the ionic effects of irrigation water on soil processes would be more complex than we currently understood, which should attract increasing concerns in the future.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0341816218303989-ga1.jpg" width="492" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 172〈/p〉 〈p〉Author(s): Atulya Kumar Mohanty, V.V.S. Gurunadha Rao〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Groundwater is the major source of freshwater in coastal areas, and gradual declining of water quality is a major cause of concern. The present study is focused on a coastal aquifer, to study the groundwater chemistry, hydrogeochemical characteristics, and salinization processes in a coastal area of the Puri District of Odisha, southeastern coast of India. Groundwater chemistry reveals, water compositions are generally near neutral to slightly alkaline nature in pH, and the total dissolved solids (TDS) concentrations varies from 150 mg/l in the inland area to 4006 mg/l towards the shorelines. Piper plot shows four principal hydrochemical water types prevailed in the groundwater zones with water composition changes from fresh water to the saline water mixing. The oxygen isotope (δ〈sup〉18〈/sup〉O) values are found between −5.3‰ to and −2.96‰, which indicates groundwater compositions were influenced by the evaporation process. Based on Cl〈sup〉−〈/sup〉 concentrations (0.4–35 meq/l), the saline end-member is mixing of seawater with the groundwater. Calculations of ionic deltas in groundwater show deficiency of Na〈sup〉+〈/sup〉, Ca〈sup〉2+〈/sup〉, Mg〈sup〉2+〈/sup〉, SO〈sub〉4〈/sub〉〈sup〉2−〈/sup〉 ions and significantly mixed with seawater and subsequent reactions governed by ion exchange processes in the aquifer. Saturation index shows groundwater were subsaturated to near equilibrium conditions with mineral phases such as dolomite, gypsum, halite and under-saturated with calcite, aragonite and anhydrite. Sulphate depletion observed in groundwater indicates the seawater mixing. Groundwater flow path shows, there is a gradual increasing of TDS concentrations from inland recharge areas to towards the discharge areas of shoreline and groundwater facies changes from Na-K-HCO〈sub〉3〈/sub〉 to Na-Mg-Cl type. The coastal aquifers are subjected to the continuous influence of seawater mixing, dissolution of carbonate phase minerals, aided with rock-water interaction, and ion exchange processes are the significant governing factors, which controls the groundwater evolution.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 172〈/p〉 〈p〉Author(s): Ruzhen Wang, Feike A. Dijkstra, Heyong Liu, Jinfei Yin, Xue Wang, Xue Feng, Zhuwen Xu, Yong Jiang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We examined the effect of nitrogen and water addition on soil carbon pool dynamics in a semi–arid grassland field experiment. Soils were sampled over a four–year period at different soil depths and analyzed for total soil organic carbon (SOC), oxidizable C (OxC), lignin and total nitrogen (TN) in bulk soil and the silt and clay fraction (〈53 μm). We found that water but not N addition increased SOC (by 18.1%), OxC (by 12.2%), and TN (by 15.1%) in bulk soil. In contrast, SOC, OxC, and TN in the silt and clay fraction showed no change in response to both N and water addition. Both N and water addition showed no effect on total lignin concentration in soils. A more enriched 〈sup〉13〈/sup〉C and lower C:N ratio in the silt and clay fraction indicated enhanced microbially processed C of relatively greater stability in this fraction compared to the bulk soil. Water addition promoted soil C sequestration by enhancing C input from plant materials as evidenced from more depleted soil δ〈sup〉13〈/sup〉C compared to the ambient precipitation. We suggest that the increase in OxC was likely one of the main drivers of the larger SOC concentration with higher water inputs. Soil C fractions in subsoils were also affected by exogenous resource inputs in a similar way as surface soils. Future modeling work on soil C sequestration should consider the relative contribution of OxC and mineral–associated C to SOC changes.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0341816218303588-ga1.jpg" width="371" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 172〈/p〉 〈p〉Author(s): Chenhua Li, Yan Li, Jiangbo Xie, Yan Liu, Yugang Wang, Xuecan Liu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The maintenance and accumulation of soil organic carbon (SOC) is critical to the agricultural sustainability and environmental stability in oasis-desert belts. The objective of this study was to determine the effects of oasis formation on SOC and aggregate structure, as well as the linkage between them, throughout a 0–200 cm soil profile. The investigation was conducted in five oases at the northern foot of the Tianshan Mountains in Central Asia. Oasis farmlands reclaimed 3, 5, 10, 20, 50, and 〉100 years ago were compared with the desert pairs they originated from. The SOC content significantly increased throughout the whole profile after 20 years of reclamation, despite a loss in the first 10 years of reclamation. The values reached maxima at 50 years of reclamation, which increased by 67–135% compared to initial values. The macro-aggregate (diameter 〉 0.25 mm) fraction with high carbon (C) concentration significantly increased throughout the soil profile after reclamation, and showed the greatest variation during oasis formation, compared with the other aggregate fractions (0.25–0.053 and 〈0.053 mm). These changes were significantly correlated with increases in soil nutrients and microbial biomass and decreases in soil pH and salt during oasis formation. In conclusion, the oasis formation enhanced SOC accumulation not only in topsoil but also in deep soil, and soil aggregate structure was improved by increased macro-aggregates. The formation of macro-aggregates and the increase in their associated C had significant correlations with SOC accumulation. Fertilization, especially inorganic nitrogen, very likely promoted the SOC accumulation and soil aggregation in concert with annual input of crop residues into the originally poor desert soils during oasis formation.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 173〈/p〉 〈p〉Author(s): Mohan Lal, S.K. Mishra, Mukesh Kumar〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The present study evaluates the performance of five existing and three proposed antecedent moisture condition (AMC)-based runoff curve number (CN) conversion formulae utilizing the data of a large number of naturally observed rainfall (P)–runoff (Q) for an agricultural field located at Roorkee, Uttarakhand, India and available published data around the globe. For developing the proposed formulae, CNs were derived for P–Q datasets from 39 watersheds using standard initial abstraction ratio (λ) values as 0.20 and 0.030. The existing formulae outperformed the proposed formulae when tested numerically using the available National Engineering Handbook chapter–4 (NEH–4) tabular AMC-dependent CNs as target values. It might be because the existing formulae were derived from the same datasets used as targeted values (i.e. NEH–4 AMC defining tables). Therefore, when tested on large set of field data, the three proposed formulae performed better than the existing ones, the formula with λ = 0.030 the best of all.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 172〈/p〉 〈p〉Author(s): Justyna Jasińska, Piotr Sewerniak, Maciej Markiewicz〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Litter decomposition has been widely studied and described in literature; however, so far rate of the process has not been investigated and described in detail with regard to inland dunes, despite them being common landforms in many regions of the world. The aim of our study was to show links between the topographically-induced variation in some main drivers of litter decomposition (microclimatic parameters, soil properties, vegetation) and the rate of the process on inland dunes. Our 3-year experiment was conducted on contrasting slope aspects (north- and south-facing slopes) of dunes representing the early and mature stages of pine forest development. On each slope the rate of litterfall decomposition (mineralisation and humification) was investigated using the litterbag method. The materials used for the experiment were the dominant category of litterfall for each plot and these were placed in 15 × 15-cm nylon mesh bags with 2 × 2-mm mesh. Litterbags were placed on the soil surface in the middle of each of the studied slopes. The chemical composition (C, N, P, K, Mg, Mn, Ca, Fe, Al) of initial litterfalls and of materials representing subsequent stages of decomposition was analyzed. The results were linked to topographically-induced variations in microclimatic parameters (air temperature and relative air humidity automatically recorded with HOBO U23-001 loggers) soil temperature and moisture (TDR method). In a mature pine stand, the rate of litterfall decomposition was faster on north- than south-facing slopes, while for the early stage of forest development the relationship was the opposite. The main agent of the differences for the mature stand was soil moisture and subsequent higher density of microbial decomposers, while for the early stage it was the difference in the initial chemical properties of the litterfall. Our results indicate that slope aspect significantly affects the rate of litter decomposition on the dunes by spatially differentiating the main drivers of the process.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 173〈/p〉 〈p〉Author(s): Dorota Kulikowska, Barbara K. Klik, Zygmunt M. Gusiatin, Rafał Jabłoński〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The search for washing agents recovered from waste is a new trend in the washing of soils contaminated with heavy metals (HMs). In the present study, dissolved organic matter (DOM) recovered from sewage sludge was used to remediate soil that originated from a metallurgical area and was contaminated with Cu (8109 mg kg〈sup〉−1〈/sup〉), Pb (1473 mg kg〈sup〉−1〈/sup〉) and Zn (531 mg kg〈sup〉−1〈/sup〉). At pH 4 and a washing agent concentration of 4 g TOC dm〈sup〉−3〈/sup〉, HMs removal proceeded according to pseudo-second-order kinetics with a relatively short equilibrium time (120 min). DOM was especially effective for removing Cu; in double washing, Cu removal was 5854 mg kg〈sup〉−1〈/sup〉 (process effectiveness 72%), Zn removal was 258 mg kg〈sup〉−1〈/sup〉 (process effectiveness 50.5%), but Pb removal was low (131 mg kg〈sup〉−1〈/sup〉; 8.7%). DOM effectively removed metals from the exchangeable and acid soluble fraction. Based on the reduced partition index (I〈sub〉R〈/sub〉), the intensity of Cu and Zn bonding in soil washed with DOM was twice as high as that in unwashed soil. Thus, DOM can serve as an effective washing agent for remediating soils contaminated with Cu and Zn, but it is not useful for removing Pb.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 172〈/p〉 〈p〉Author(s): Antonio Aparecido Couto, Fabiano Tomazini da Conceição, Alexandre Martins Fernandes, Eder Paulo Spatti, Cenira Maria Lupinacci, Rodrigo Braga Moruzzi〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In the last decades, the use of biofuels as a mitigation measure for carbon emissions has led to land use and land cover changes in southeastern Brazil, especially in Paulista Peripheral Depression – Paraná Sedimentary Basin. Considering the human-landscape system associated with energy policy, these changes can affect landscape and natural resources over a range of temporal and special scales. Thus, the aim of study was on how human-landscape interactions have influenced the geomorphological dynamics in a São Paulo region that contains sugar cane crops associated with soils derived from sandstones and mudstones. The use of the Universal Soil Loss Equation (USLE) in three different scenarios from land use changes allowed verifying how they have affected soil loss: natural conditions (savannah), current land use and with the expansion of sugar cane crops. In addition, the total sediment transported, the sediment delivery ratio and the rate of soil removal were measured, considering the current land use. The land use scenarios pointed out that the land use change is directly related to increasing rates of soil loss, i.e. 0.03, 3.5 and 12.6 t ha〈sup〉−1〈/sup〉 yr〈sup〉−1〈/sup〉 for the natural conditions, current land use and with the expansion of sugar cane crops, respectively. These rates in the current land use and with continuous expansion of sugar cane crops are higher than the tolerable erosion limits in 17 and 57% of the study area, respectively. The suspended sediment concentration increases with increasing Cachoeirinha Stream discharge, with a specific daily flux of 88 kg km〈sup〉−2〈/sup〉 day〈sup〉−1〈/sup〉. The mean monthly flux in 2014 was 32 t month〈sup〉−1〈/sup〉, with varying from 3.1 (August) to 144 (January) t month〈sup〉−1〈/sup〉. The wet period was responsible for ca. 90% (436 t) of the total solids transported in 2014. The sediment delivery ratio was 9% of the total soil loss. The current rate of soil removal of 25.8 m Myr〈sup〉−1〈/sup〉 is almost 3-fold higher than the long-term denudation rates suggested for the Peripheral Depression (9 m Myr〈sup〉−1〈/sup〉). With the continuous expansion of sugar cane crops, the rate of soil removal probably will be higher than that obtained in the current scenario and, consequently, the current denudation rates should increase further. Thus, this study reinforce that the human-landscape systems in São Paulo State associated with energy policy are complex and increase the natural processes of soil removal and, consequently, affect the landscape evolution.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 172〈/p〉 〈p〉Author(s): Dominika Krzeminska, Tjibbe Kerkhof, Kamilla Skaalsveen, Jannes Stolte〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉The hydrological processes associated with vegetation and their effect on slope stability are complex and so difficult to quantify, especially because of their transient effects (e.g. changes throughout the vegetation life cycle). Additionally, there is very limited amount of field based research focusing on investigation of coupled hydrological and mechanical influence of vegetation on stream bank behavior, accounting for both seasonal time scale and different vegetation types, and none dedicated to marine clay soils (typically soil type for Norway).〈/p〉 〈p〉In order to fill this gap we established hydrological and mechanical monitoring of selected test plots within a stream bank, covered with different types of vegetation, typical for Norwegian agricultural areas (grass, shrubs and trees). The soil moisture, groundwater level and stream water level were continuously monitored. Additionally, soil porosity and shear strength were measured regularly. Observed hydrological trends and differences between three plots (grass, tree and shrub) were analysed and formed the input base for stream bank stability modeling. We did not find particular differences between the grass and shrub plot but we did observe a significantly lower soil moisture content, lower soil porosity and higher shear strength within the tree plot. All three plots were stable during the monitoring period, however modeling scenarios made it possible to analyse potential differences in stream bank stability under different vegetation cover depending on root reinforcement and slope angle.〈/p〉 〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 172〈/p〉 〈p〉Author(s): Renjie Hou, Tianxiao Li, Qiang Fu, Dong Liu, Song Cui, Zhaoqiang Zhou, Peiru Yan, Jiawen Yan〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The goal of this study was to explore the effect of the collocation coverage of snow and straw on the complexity variation of soil water and heat and its appropriate evaluation method during freeze-thaw periods in the Songnen Plain of China. Based on field trials, the characteristics of the spatial variability in soil water and heat and the correlation between the water/heat in snow and in soil were analyzed under conditions of bare land (BL), natural snow (FB0), natural snow plus 5-cm-thick straw (FB5) and natural snow plus 10-cm-thick straw (FB10). Additionally, a spectral entropy algorithm based on Fourier transform was used to calculate the spectral entropy of the soil water and heat sequences, and the spatial variation law of soil water and heat complexity in vertical section was explored; furthermore, the positive effect of straw on the soil water and heat environment was revealed. (1) During the freezing period (i.e., the rapid freezing period and stable freezing period), the collocation coverage of straw and snow weakened the differences between the surface soil and the deeper soil; furthermore, the presence of straw hindered the energy exchange between snow and soil, and as the amount of straw coverage increased, the difference between snow water/heat and that in soil increased. During the melting period, the infiltration of snowmelt water affected the variation of soil water and heat, whereas the straw, due to its water storage characteristics, absorbed large amounts of snowmelt water and provided a stable water supply to the soil. With the increase of straw coverage, the correlation between snow water/heat and that in soil was increased under the FB5 and FB10 treatments. (2) The spectral entropy algorithm evaluation values were in good agreement with the classical statistical analysis, demonstrating that the algorithm can be used to efficiently and accurately evaluate the complexity of soil water and heat time series. The spectral entropy of soil water and heat in the 10-cm soil layer under the treatments of FB0, FB5 and FB10 was less than the corresponding entropy under the BL treatment during rapid freezing and stable freezing periods. As the soil depth increased, the spectral entropy decreased under the different treatments. Affected by the maximum freezing depth, the soil water and heat spectral entropy values peaked in the vertical section during the stable freezing period; as the amount of straw coverage increased, the position of the peak value gradually increased. However, during the melting period, the complexity of soil water and heat under the three snow cover conditions increased significantly relative to that under the BL treatment. As the straw coverage increased, the complexity of soil water and heat decreased. The complexity evaluation method of the spectral entropy algorithm is reliable, and the measurement accuracy meets the evaluation requirements. The algorithm has application value for the evaluation of soil water and heat variation in cold regions.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 172〈/p〉 〈p〉Author(s): Jiangbo Gao, Huan Wang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In karst areas, soil erosion is a significant problem, seriously impeding sustainable socioeconomic development. A thorough understanding and quantitative identification of the influencing factors are essential for soil erosion protection and rocky desertification management. This study identifies the dominant factors (and interactions) influencing soil erosion and its spatiotemporal variability in a karst basin, the Sancha River Basin, China. The geographical detector method was used to conduct the quantitative attribution analysis, based on the modified universal soil loss equation model for karst environments. The results revealed that karst soil erosion exhibited a notable decreasing trend over the past 36 years (p 〈 0.01), decreasing from 16.70 t ha〈sup〉−1〈/sup〉 a〈sup〉−1〈/sup〉 in 1980 to 12.22 t ha〈sup〉−1〈/sup〉 a〈sup〉−1〈/sup〉 in 2015. The geographical detector results indicated significant differences in the strength of the association between influencing factors (or factor combinations) and karst soil erosion. Land use type was the dominant factor, followed by slope; a combination of land use type and slope was the dominant interaction factor, explaining at least 74% of the karst soil erosion distribution. Land use change dominated karst soil erosion dynamics in the 1980s and 1990s, and rainfall variability dominated in the 2000s. In addition, karst soil erosion showed high spatial heterogeneity, and the strength of the association differed substantially among diverse geomorphological types due to differences in the inner characteristics of each. These findings suggest that the characteristics of different geomorphological types should be considered for effective management and prevention of soil erosion at a regional level, and that steep croplands, especially with slopes higher than 15°, should be prohibited in karst areas. The methodology and framework can be used to better understand the relationships between soil erosion and its influencing factors in karst areas.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S034181621830359X-ga1.jpg" width="330" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 172〈/p〉 〈p〉Author(s): Jairo C. Oliveira Junior, Sheila A.C. Furquim, Alexandre F. Nascimento, Raphael M. Beirigo, Laurent Barbiero, Vincent Valles, Eduardo G. Couto, Pablo Vidal-Torrado〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Salt-affected soils play an important role in the Pantanal wetlands ecosystem, in Brazil, but their occurrence on higher landforms is not well understood. In order to investigate the major processes involved in salt-affected soil formation, a trench was opened in a representative transition between the floodplain and a paleochannel-paleolevee complex not currently reached by floodwater. The trench was 6 meter long and 2 meter deep, and 121 soil samples were collected in a 0.25 × 0.25 m regular grid and submitted for soil (particle-size, pH, exchangeable cations) and solution extract (major cation and anions) analyses. Analytical results were subjected to geostatistical and principal components analyses (PCA). For selected horizons, an undisturbed sample was collected to perform thin sections and micromorphology description. The presence of degraded carbonates in the soils indicated an ancient formation. The regional environmental settings of the alluvial fan and particle size variation along the soil profiles suggested that the sediments of the study site were deposited during the Late Pleistocene and Holocene, in a river channel-levee complex and an abandoned channel by avulsion processes. The depressed topography of the abandoned channel, accompanied by moderately drier climates during early Holocene, likely favored low leaching of salts and higher evapotranspiration, enabling the development of salt-affected soils. Later erosion of the region, which is expected in older lobes of alluvial fans, triggered a relief inversion in the area, preserving the more clayey areas as a slightly higher landform with remaining salt-affected soils. Currently, the seasonal flooding mainly reaches the footslope of this landform, triggering redoximorphic processes, expressed as redox concentrations and depletions, and solodization processes, expressed by lower values of pH, cation exchange capacity (CEC), base saturation and exchangeable sodium percentage (ESP) than at the summit. Thus, the occurrence of salt-affected soils on higher landforms is the reflection of a complex sedimentological history. In this way, the genesis of salt-affected soils on higher landforms, which seems to be poorly understood in many situations worldwide, should be carefully investigated in order to address formation mechanisms, especially in extremely dynamic environments of tropical wetlands.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 172〈/p〉 〈p〉Author(s): Qinglin Chai, Zhanying Ma, Xiaofeng Chang, Gaolin Wu, Jiyong Zheng, Zhongwu Li, Guojie Wang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Grassland recovery from degradation is increasingly occurring worldwide. Diverse managements have been considered as effective ways to restore degraded grassland, but it remains unclear how semi-arid grasslands respond to long-term grazing exclusion and fenced mowing. Here, a study was conducted under open grazing, grazing exclusion and fenced mowing in a semi-arid grassland on the Loess Plateau. We measured plant species composition and diversity, plant production, surface litter and soil water and carbon content. Shifts in grassland management led to significant divergence in plant community composition. Long-term grazing exclusion (35 years) significantly increased plant biomass, surface litter, soil water and carbon storage, but suppressed plant diversity compared to open grazing. Conversely, fenced mowing significantly increased plant diversity accompanying with a weak effect on soil carbon. Moreover, mowing significantly reduced surface litter and soil moisture, which have strong implications for nutrient depletion and soil drying. Our results suggest that introducing disturbances are necessary to safeguard biodiversity, and continuous mowing (5 years) belongs to over exploitation of the long-term protected grassland. Therefore, it is essential to optimize management with dual objectives of biodiversity and soil carbon sequestration in the future.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 172〈/p〉 〈p〉Author(s): Ivan Lizaga, Laura Quijano, Leticia Gaspar, María Concepción Ramos, Ana Navas〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Several decades of intensive rainfed farming in Mediterranean mountains and later land abandonment has led to rapid land use and land cover changes. During recent centuries, the conversion of rangelands into croplands has increased the surfaces prone to erosion. In the southern Pre-Pyrenees, the process was reversed during the middle of the twentieth century, allowing the recovery of vegetation and subsequent variation in land cover. This work aims to assess how land use changes after generalised land abandonment affect some major soil properties related to soil quality. For this purpose, 98 replicate bulk soil samples were collected in a 23 km〈sup〉2〈/sup〉 catchment that was mostly cultivated at the beginning of the last century. Soil samples were distributed over areas representing the main land uses (agricultural land, natural forest, pine afforestation and scrubland). Bulk density, stoniness, grain size, pH, carbonates, electrical conductivity, soil organic carbon (SOC), total nitrogen (TN), water retention capacity and magnetic properties (low frequency magnetic susceptibility (LF) and frequency dependence (FD)) were analysed in the samples from different land use areas. A past scenario was recreated using estimated data from the SPEROS-C model in order to evaluate changes in SOC over time. Furthermore, a multitemporal analysis of the Normalised Difference Vegetation Index of Landsat images was performed between 1972 and the present in order to assess the dynamics of revegetation. After land abandonment, 16.5% of the area remained as croplands, but afforestation and natural revegetation occupied 83.5% of the catchment. The highest mean value for SOC was found in the pine afforested area and the highest TN mean value was found in the natural forest. The lowest mean values for SOC and TN were recorded on the agricultural land. These results show the impact of soil changes produced by land use changes in fragile Mediterranean mountain agroecosystems.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0341816218303874-ga1.jpg" width="301" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 173〈/p〉 〈p〉Author(s): Lili Gao, Bisheng Wang, Shengping Li, Huijun Wu, Xueping Wu, Guopeng Liang, Daozhi Gong, Ximei Zhang, Dianxiong Cai, Aurore Degré〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In the Loess Plateau of China, conventional tillage is defined as the tillage without crop residues left on the soil surface and ploughed twice a year. The use of alternative practices is a way to reduce soil erosion. Our objectives were to assess the long-term impacts of different soil tillage systems on soil physical and hydraulic characteristics, emphasizing management practices to improve the soil physical qualities (reduce bulk density and increase stability of aggregate) under the conservation tillage system in the Loess Plateau of China. Conventional tillage (CT), no tillage (NT), and sub-soiling (SS) were applied in this experiment. Soil wet aggregates distribution and stability, soil organic carbon (SOC) content, soil water retention curves and pore size distributions were measured. The results showed that in the 0–10 cm and 10–20 cm depth soil layers, NT and SS treatments showed a significantly higher proportion of wet aggregates 〉250 μm (macroaggregates) compared to CT. In these two layers, the proportion of wet aggregates 〈53 μm (microaggregates) was significantly higher in CT with respect to NT and SS. SOC content increased as the aggregate fraction size increased, and was higher within wet aggregates 〉250 μm than within the 250–53 μm and 〈 53 μm (silt + clay) fractions at both depths. In addition, the conservation tillage (NT and SS) can result in improved total porosity and reduced soil bulk density compared with CT in the surface layer. Pore size distribution in CT soil was unimodal, with the maximum in the 10–30 μm matrix pores of the surface layer. However, in the surface layer the pore size distributions from NT and SS showed a dual porosity curve, with two peaks in the matrix and structural pore areas. The 10–20 cm layer showed similar pore size distributions in each treatment. After scanning the soils by micro-computed tomography, we visualized the pore characteristics. The images showed that CT reduced the long and connected macropores compared with conservation tillage. Overall, soil aggregate stability and soil macropores are most improved under conservation tillage. Conservation tillage with crop residues should be adopted instead of conventional tillage, as an effort to improve crop yield and control soil erosion in the Loess Plateau of China.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 172〈/p〉 〈p〉Author(s): Érica de Oliveira Silva, Erika Valente de Medeiros, Gustavo Pereira Duda, Mario Andrade Lira Junior, Michel Brossard, Julyana Braga de Oliveira, Uemeson José dos Santos, Claude Hammecker〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Tropical environments are considerable contributors to overall soil carbon loss to the atmosphere. Land use effects on soil chemical attributes have been well documented mainly in humid environments; however, less attention has been paid to the changes in soil enzymatic activities in dry ecosystems that is a sensitive indicator in ecological processes, due to its importance in soil dynamics and microbial activity. The present study is part of interdisciplinary project that investigated the effect of land cover type and seasonal variation on absolute and specific enzymatic activities per unit of soil organic carbon (SOC) and per microbial biomass carbon (MBC). We assessed five different land use type (Tropical dry forest-TDF, protected area with Angico –ANA, protected area with Ipê-TAB, Scrub area-SCR and agricultural area with maize-M) and five areas of each land use in three layers: 0–0.05, 0.05–0.10 and 0.10–0.20 m. The samples were collected at rainy season 1 in April 2014 (RS1), dry season October 2015 (DS) and rainy season 1 April 2016 (RS2). The conversion of the preserved area provided a reduction in absolute enzymatic activities, especially in the SCR and M. The reductions were of 76% for β-glucosidase, 95% for urease and 72% for acid phosphatase. The specific enzymatic activities per unit of MBC increased with the change of soil use, except in M. The enzymatic activity per unit of SOC in the TDF area was higher in relation to the other areas evaluated, except for specific activity of acid phosphatase. The land use type influenced the absolute and specific soil enzyme activities, but not show a clear trend of seasonal effect.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 172〈/p〉 〈p〉Author(s): Benli Liu, Jianjun Qu, Duihu Ning, Qingjie Han, Daiying Yin, Pengfei Du〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We present a new wind erosion estimation model (Wind Erosion from CONstruction activities, WECON) that is designed for not only flat surfaces but also land that has been disturbed by construction or engineering activities. The core of the model is based on the maximum soil loss potential from wind erosion. The factors that were considered include wind speed, wind direction, plot dimension, particle size, soil water content, surface coverage, soil loosening, and pile height and arrangement. The model can be run in two settings: one using observation wind data and one using long-term meteorological data when observation records are absent. The model is robust in reflecting the factors influencing wind erosion when compared to field observations and wind tunnel experimental results. Portable software with a database containing information from 1781 meteorological stations across China was compiled so that users can conveniently estimate wind erosion in different locations with different (including natural or undisturbed) surface conditions.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 172〈/p〉 〈p〉Author(s): Yuan Li, Haibo Zhang, Chuancheng Fu, Chen Tu, Yongming Luo, Peter Christie〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Clay-enriched layers occurring in deltas are important as they reveal erosion, transportation and deposition of source materials from the basin to the coast. In the Yellow River Delta a red clay layer (RCL) with a thickness of 5–50 cm at 1 m depth in the soil profile occurs in the floodplain area dominated by fluvo-aquic soil derived from Yellow River sediments. The RCL typically has a median grain size of 〈20 μm, redness (a〈sup〉⁎〈/sup〉) of 〉7, and relatively high contents of illite, calcite and iron oxides. In the Loess-Yellow River sediment-Yellow River Delta soil continuum a regime of weathering, mechanical sorting and dilution by carbonates and silica have been important factors altering the elemental geochemistry. The abundance of secondary minerals and deficiencies of silica and zircon in the RCL suggest that it was separated from a mixed source and was likely derived from highly weathered sediments (such as paleosol) from the basin. RCL samples show substantial accumulation of inorganic carbon with enhancement of the organic carbon content, indicating that increasing organic carbon in alkaline soils may lead to an increase in inorganic carbon in the subsoil. Large variations in elemental ratios have been found in the RCL characterized by excess nitrogen and trace metals and phosphorus deficiency due to adsorption and weathering effects. Implementation of the water-sediment regulation scheme (WSRS) may have altered the sedimentary environment and may have aggravated an elemental imbalance due to the occurrence of the yellow silt layer (YSL)-RCL sequence and thereby impacted biogeochemical cycling in the river-delta-coast continuum.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0341816218303837-ga1.jpg" width="315" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 172〈/p〉 〈p〉Author(s): P.I.A. Kinnell〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉RUSLE2 is a rainfall erosion model that, in its standard mode, predicts long term soil losses as an aid to making decisions related to soil conservation in the USA. In recent times, RUSLE2 has developed a capacity to predict event soil losses using user entered data for event rain and 〈em〉EI〈/em〉〈sub〉〈em〉30〈/em〉〈/sub〉. WEPP is a more process based model which uses a stochastic weather generator, CLIGEN, to generate events that are stochastically distributed in time. CLIGEN does not estimate event 〈em〉EI〈/em〉〈sub〉〈em〉30〈/em〉〈/sub〉 values for the rainfall events it generates but it is possible to do so through use of erosivity densities (〈em〉EI〈/em〉〈sub〉〈em〉30〈/em〉〈/sub〉 per unit quantity of rainfall) data available in RUSLE2. This enables CLIGEN to be used as a climate generator for RUSLE2 and provides the capacity to use RUSLE2 in roles similar to the ones where WEPP is being applied.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 172〈/p〉 〈p〉Author(s): Sushil N. Mhaske, Khanindra Pathak, Arnab Basak〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The present paper describes the design of a comprehensive rainfall simulator which is particularly meant for the assessment of soil erosion at plot scale by considering various soil grain types, soil slope angles, and surface exposures under different rainfall conditions. The entire setup is divided into four major parts: (a) water supply system with single spray nozzle, (b) supporting metal frame, (c) hydraulic jack attached container table for slope adjustment, and (d) temperature simulator. It covers an area of 3 m〈sup〉2〈/sup〉, out of which 0.5 m〈sup〉2〈/sup〉 is the target area or experimental plot and the simulated raindrops fall from a height of 2.3 m. Four types of full-jet spray nozzles are used to simulate rainfall intensities of 65, 93, 112, and 148 mm/h. The experimental plot can attain a maximum slope angle of 40° using a hydraulic jack unit. A temperature simulator is designed to replicate the natural conditions in the laboratory. Physical and numerical simulations are carried out to measure the characteristics of simulated rainfall and compare with those of natural rainfall conditions. The Christiansen coefficient (〈em〉Cu〈/em〉) of the designed rainfall simulator varies from 81〈em〉%〈/em〉 to 88〈em〉%〈/em〉. The rain droplet size ranges from roughly 1 mm to 5 mm and their corresponding terminal velocities range from 4.76 m/s to 10.64 m/s, striking velocities are found between 5.56 m/s and 9.63 m/s, and kinetic energies ranging from 0.0081 mJ to 3.0342 mJ. The total kinetic energy of the raindrops striking the soil surface in the entire plot area of 0.5 m〈sup〉2〈/sup〉 depends on the rainfall intensity and varies from about 6 J to 12 J. The designed setup is capable of simulating rainfall inside the laboratory with properties very close to those of natural rainfall. We adopt the Taguchi fractional factorial design of experiments to investigate the effects of different factors on soil erosion. Furthermore, statistical analysis of the experimental data is carried out by using signal-to-noise (〈em〉S〈/em〉/〈em〉N〈/em〉) ratio and the optimum condition for maximum soil erosion is predicted. The main objectives of this study are to design a comprehensive rainfall simulator setup, evaluate the properties of the simulated rainfall, provide a theoretical model and assess the several factors affecting soil erosion using reduced number of experiments in the laboratory.〈/p〉〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 172〈/p〉 〈p〉Author(s): Lian Liu, Quan Li, Min Huang, Yan Yang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The carbon concentration and carbon isotope of black carbon (BC) have been widely used to reconstruct fire history and vegetation change. In order to establish the relationship between BC, contemporary vegetation and climate at the high altitudes of the Qinghai-Tibetan Plateau (QTP), we investigated the carbon concentration and carbon isotope composition of BC and soil organic carbon (SOC) (%BC, %SOC, 〈em〉δ〈/em〉〈sup〉13〈/sup〉C〈sub〉BC〈/sub〉 and 〈em〉δ〈/em〉〈sup〉13〈/sup〉C〈sub〉SOC〈/sub〉) in 29 topsoil samples from the central and southeastern QTP. In general, the %SOC and %BC of topsoil show generally similar variations, indicating a common controlling factor for SOC and BC production, i.e., vegetation. The relatively small BC/SOC ratios fall in the range of BC/OC for pyrogenic particles from biomass burning, indicating a minor contribution of BC from fossil fuel combustion. The 〈em〉δ〈/em〉〈sup〉13〈/sup〉C〈sub〉SOC〈/sub〉 of topsoil can effectively indicate local vegetation in the QTP. The 〈em〉δ〈/em〉〈sup〉13〈/sup〉C〈sub〉BC〈/sub〉 and 〈em〉δ〈/em〉〈sup〉13〈/sup〉C〈sub〉SOC〈/sub〉 are positively correlated, whereas the 〈em〉δ〈/em〉〈sup〉13〈/sup〉C〈sub〉BC〈/sub〉 values are more negative than those of 〈em〉δ〈/em〉〈sup〉13〈/sup〉C〈sub〉SOC〈/sub〉. This could due to fire season and fractionation processes during post-deposition, but not carbon isotope fractionation during combustion or exogenous BC input. Therefore, BC in topsoil of the QTP mainly records ‘local’ environmental information, and the 〈em〉δ〈/em〉〈sup〉13〈/sup〉C〈sub〉BC〈/sub〉 can be used in paleovegetation reconstruction in combination with the local climate.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 172〈/p〉 〈p〉Author(s): Nannan Ge, Xiaorong Wei, Xiang Wang, Xuetong Liu, Mingan Shao, Xiaoxu Jia, Xuezhang Li, Qingyin Zhang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Organic carbon (OC) and nutrient dynamics are closely related to soil texture, but how texture influences the distribution of OC and nutrients in aggregates in various land use types has not been examined. This knowledge gap precludes our mechanistic understanding of soil biogeochemical cycles at large spatial scales. Herein we compared the contents and stoichiometric ratios of OC and nutrients in both bulk soils and aggregates in cropland and woodland across a clay content gradient (7–31%) in the Loess Plateau. The soil metrics that were measured included the proportions of water-stable aggregates, and the contents of OC, nitrogen (N) and phosphorous (P) in bulk soils and each aggregate fraction. The stoichiometric ratios of carbon (C), N and P were calculated. The relationships between soil metrics and clay content were analyzed. We hypothesize that OC, N and P in aggregates increase with clay content, and these relationships are independent of land use types. In partial support of these hypotheses, the proportion of macroaggregates and the contents of OC, N and P in bulk soils and most aggregate fractions linearly increased with clay content. The slopes of these linear relationships were not affected by land use type. The C/N ratio were minimally affected, while the C/P and N/P ratios in both bulk soils and aggregates increased with clay content, and these relationships changed with land use type. Proportion of macroaggregates, contents of OC and N, and ratios of C/N, C/P and N/P were significantly higher in woodland than in cropland across or within sites. Furthermore, the distribution patterns of OC, N and P contents, and C/P and N/P ratios among aggregates varied with site and land use type. These suggested that soil texture determines the distribution of OC, N and P and their stoichiometric ratios within soil aggregates in the Loess Plateau of China, and most of these determining relationships were independent from land use types.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 172〈/p〉 〈p〉Author(s): Svetlana Sycheva, Olga Khokhlova, Polina Pushkina, Pavel Ukrainsky〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉A 〈em〉catena〈/em〉 of the Holocene soils and interstadial Bryansk paleosol has been studied within a small closed depression in the Kazatskaya Steppe site on the Central Russian Upland. This depression is located on the territory of the Central Chernozem Biospheric Reserve, Kursk region and presumably originated from suffosion processes. Our research is aimed at understanding of interrelations between the macro- and micromorphological characteristics, certain physical and chemical properties of the Bryansk paleosols, on one hand, and those of the superimposed Holocene soil on another, taking into consideration various conditions of the present-day microrelief. The studied 〈em〉catena〈/em〉 is a typical component of the landscape and soil cover structure for watersheds of the Central Russian Upland. On the micro-elevation rising 80 cm above the micro-depression bottom, the Typical Chernozems (Haplic Chernozems) are developed, on the slope – the Leached Chernozems (Luvic Chernozems), and at the bottom – the Meadow Chernozems (Stagnic Chernozems). The upper humus horizons of the Holocene soil present in all sectors of the 〈em〉catena〈/em〉. The thickness of the Ah horizon increases slightly, whereas the AB horizon decreases toward the bottom of the depression. On the slopes and at the bottom of the depression, the Ah2 sub-horizon is replaced with the AE horizon, and the Bk horizon becomes carbonates-free and turns into the Bt horizon.〈/p〉 〈p〉The change of the “normal” profile of paleosol of warm interstadial in final phase of MIS 3 started already in the last stages of its formation. The Bryansk soil is heavily deformed by cryogenic processes during the Valdai glaciation maximum (the Vladimir cryogenic horizon, MIS 2). The secondary diagenesis of the Bryansk paleosol is related to the Holocene soil-forming processes. The Holocene soils are superimposed on the Middle Valdai Bryansk paleosol, transforming it in different ways in different sectors of 〈em〉catena〈/em〉. On micro-elevation the Holocene diagenesis is minimal and consists in fragmentation by mesofauna, additional penetration of carbonates in the upper horizon of the paleosol. At the bottom of the micro-depression the Bryansk paleosol is the most transformed, and the entire profile of the Bryansk soil turned into illuvial horizon of the Holocene meadow-chernozem soil.〈/p〉 〈/div〉 〈/div〉

Description: 〈p〉Publication date: February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 173〈/p〉 〈p〉Author(s): Carlos R. Mello, Léo F. Ávila, Henry Lin, Marcela C.N.S. Terra, Nick A. Chappell〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Brazilian Atlantic Forest is recognized by the UNESCO as one of the most important biosphere reserves on the planet but is threatened by extinction. The objective of this study was to analyze the main components of the water balance in an Atlantic Forest (Neotropical Forest) catchment in the Mantiqueira Range, Brazil, which is a Tropical Montane Cloud Forest. The main focuses was to analyze baseflow, evapotranspiration, soil moisture, and canopy rainfall interception to understand the hydrologic dynamics in this specially important montane forest. On average from the two studied hydrological years (2009/2010 and 2010/2011), evapotranspiration (ET), streamflow (SF), and water storage in the catchment at the end of hydrological year corresponded, respectively, to 50%, 34.8% and 15.2% of total gross precipitation (P). On average, baseflow corresponded to 73.5% of SF. The estimated potential groundwater recharge during the wet seasons was 403.8 mm (21.7% of P observed in the wet season) and 710.5 mm (28.5% of P observed in the wet season), respectively, for 2009/2010 and 2010/2011 hydrological years, showing that the catchment is able to store groundwater to provide the maintenance of the streamflow during early recessions and drought periods. Therefore, the baseflow is important in mountainous catchments in the tropical regions to provide important ecological functions, mainly as freshwater reserve.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 173〈/p〉 〈p〉Author(s): Felipe Zúñiga, Dorota Dec, Susana R. Valle, Oscar Thiers, Leandro Paulino, Oscar Martínez, Oscar Seguel, Manuel Casanova, Mario Pino, Rainer Horn, José Dörner〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉The Ñadi soils (ÑS) is a local name for soils occurring at southern Chile (38° to 43° S) covering around 4250 km〈sup〉2〈/sup〉 hectares. Derived from volcanic materials, have discontinuous iron-cemented layers (the placic horizon) which favour waterlogging during the winter. The studies of iron-cemented layers are predominant in USA and Taiwan, but we provide an overview of ÑS research to position them within the group of soils with iron-cemented layers, and to highlight the distribution, formation, processes, and the relevance of placic horizons in land use and ecosystem services that ÑS provide.〈/p〉 〈p〉We surveyed the worldwide literature of iron-cemented layers to put the Chilean soils with placic horizons. A fraction analysis was conducted in a longitudinal transect of five ÑS to evaluate the Si, Al, Fe and Mn reactive pools in the soil. A principal component analysis (PCA) was performed to separate the soil Series. Finally, a comparison between chemical properties of placic horizons and bog iron in Chile with other soils in the world was realised.〈/p〉 〈p〉Further south, the Chilean ÑS have more SOC in surface horizons thus enabling more intensive iron translocation with the reactive soils pools decreasing with the latitude. The iron-cemented layers probably consist of goethite, ferrihydrite and gibbsite. A 51.8% of bog iron are compound of Fe while only 36.2% in the placic horizon, which also have 12.1% of Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 in the molecular structure. Land uses in ÑS vary, from forestry to archaeology coexisting in these soils. In agricultural terms, we suggest a soil depth of 50 cm as the limit to drainage, shallower depth is at risk of severe soil degradation. Finally, several research questions are posed which may help to define the use and importance of the Ñadi ecosystem to the people who use the soils currently and to future generations within the context of climate change scenario.〈/p〉 〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0341816218304302-ga1.jpg" width="301" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 172〈/p〉 〈p〉Author(s): Yali Zhao, Yunqiang Wang, Li Wang, Xiaoyan Zhang, Yunlong Yu, Zhao Jin, Henry Lin, Yiping Chen, Weijian Zhou, Zhisheng An〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Soil water is a key variable for re-vegetation and environmental restoration in water-limited terrestrial ecosystems such as the Chinese Loess Plateau. Large land restoration projects (e.g., the “Grain for Green” launched in 1999 and the “Gully Land Consolidation” launched in 2011) had substantial impacts on the storage, distribution, and spatial patterns of soil water, and these factors remain poorly understood across watershed scales. We measured the amount of water stored in soil layers from the surface down to 5 m depth and characterized the vertical distribution of gravimetric soil water content (SWC) among four land uses (cropland, shrubland, forestland, and orchard), two slope aspects (shady vs. sunny), and two landforms (slope vs. gully) in three watersheds on the Chinese Loess Plateau. All three of the watersheds were affected by Grain for Green project, two were affected by the Gully Land Consolidation project (named NG and GT-T watersheds) and one was unaffected by restoration efforts (named GT-U watershed). In the three watersheds, the slope and gully SWCs varied from 2.4 to 24.2% and from 4.8 to 46.6%, respectively, during the sampling period in October 2015 (end of the rainy season). The amount and vertical distribution of slope SWC differed significantly among the land uses and between shady and sunny slopes in the three watersheds (〈em〉p〈/em〉 〈 0.05). The mean gully SWC (20.4%) was significantly higher than the mean slope SWC (8.7%) for each of the three watersheds (〈em〉p〈/em〉 〈 0.01). Gullies filled by the Gully Land Consolidation project had a large capacity to store soil water by increasing the infiltration of precipitation, which accounted for 14.7% and 11.3% of the total annual rainfall in the NG and GT-T watersheds, respectively. Filled gullies can serve as large reservoirs of soil water to relieve the problem of water shortage and can also increase the amount of land available for cultivation to ease deficits in food production. A combination of the Grain for Green project on slopes for soil conservation and the Gully Land Consolidation project in gullies for storing more soil water and increasing farmland area is an effective land restoration strategy on the Chinese Loess Plateau and is helpful for managing water cycles in regions around the world with deep soils.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 172〈/p〉 〈p〉Author(s): Jingyi Song, Xingwu Duan, Xu Han, Yawen Li, Yuxiang Li, Daming He〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The accumulation and redistribution of heavy metals in soil in a water-level fluctuation zone (WLFZ) can create ecological risks to reservoirs and reduce river health. Little is known about how heavy metals are accumulated and redistributed in the WLFZ of reservoirs with a high background value of the heavy metal in soil. The site chosen for this case study is the Nuozhadu mega reservoir in the upper Mekong River Basin, which is held back by a dam with a height exceeding 250 m. Five sampling transects were established around the reservoir. Each transect contained three vertical sampling lines representing three land-use types: forest, farmland, and rubber plantations. Soil samples were collected both in the WLFZ and in the infralittoral reference zone (IRZ), and the concentrations of the heavy metals Zn, Cr, Ni, Cu, Mn, and Fe (%) were measured in these samples. We found that the average concentrations of each of these heavy metals were higher in the WLFZ than in the IRZ. The land-use types, especially the rubber plantations and farmlands, determine the redistribution of the heavy metals in the soil of the WLFZ. The heavy metals Cu, Mn, and Ni increased with increasing elevation within the WLFZ, but the metals Cr and Zn decreased with elevation. The results of analysis of variance indicate that the soil properties had certain differences under different land-use types and inundation durations at various elevations, which partly determined the accumulation and redistribution of heavy metals in the WLFZ. We suggest that long-term monitoring of the concentration of heavy metals is needed for soil and water management in the WLFZ of the Nuozhadu reservoir.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 172〈/p〉 〈p〉Author(s): Noa Balaban, Jonathan B. Laronne, Shimon Feinstein, Gal Vaisblat〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉This study examines the variation in the concentration of eight heavy metals (Cu, Ni, Pb, Cd, Cr, Co, V, Sc) bound on suspended sediments during flow events and those deposited in channel banks. The study was undertaken in Wadi Sekher, an ephemeral flash-flood channel draining the Neot Hovav industrial chemical complex in the semi-arid northern Negev, Israel, at sites varying with bank height and distance from the industrial complex.〈/p〉 〈p〉Metal concentrations were found to be higher in the initial flow and recession than during peak flow. Bound metal concentrations were mainly affected by suspended sediment composition and concentrations. During peak flow the suspended sediment concentration rises and quartz sand is a major constituent. This leads to a decrease in bound metal concentrations, as the larger particles have a weaker affinity to binding. In six sediment samples, taken during the first 15 min of two floods, the bound metal concentrations changed similarly. These changes are suggested to represent variations in the source and cannot be attributed to dilution or binding effects.〈/p〉 〈p〉Six banks were sampled along Wadi Sekher, from the Neot Hovav hydrometric reach downstream to the confluence of Wadi Sekher and Wadi Beer-Sheva, at specified heights, following a bank-full flood. In every cross-section, a significant difference (〈em〉p〈/em〉 〈 0.01) was seen in Cu, Cd, Co, V and Sc concentrations with bank height, with highest concentrations at bank-bed intersection. Downstream variations in bound metal concentrations along Wadi Sekher were statistically (〈em〉p〈/em〉 〉 0.05) undifferentiated, indicating that the industrial area is not a source point for these metals, and that a constant input exists into the channel from tributaries along the channel.〈/p〉 〈p〉Due to the difficulty in sampling flash floods in ephemeral channels, existing data are not abundant, and our understanding of these environments is therefore limited. This study improves knowledge of interrelated variations in bound metal concentrations in fluvial deposits, in suspended sediment and in water during flash floods.〈/p〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 172〈/p〉 〈p〉Author(s): Majid Lotfalian, Taleb Yousefi Babadi, Hasan Akbari〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Cutslopes are the most important source of sediment among other parts of forest roads network. A significant amount of runoff and sediment is observed in Hyrcanian forests because of the fine-textured soil. This study investigated the effectiveness of three treatments of jute cover (JC), mulch cover (MC) and bare cutslope as control plots (CP) under the natural rainfall condition. Two months investigation on two new and old roads with silty-clay cutslopes was done. Correlation between some of soil properties, soil loss and runoff showed that the sediment concentration was increased with increasing in soil bulk density. Runoff volume showed a significant negative correlation with the percentage of organic matter and a positive correlation with the plastic limit. With runoff volume increasing, sediment concentration and soil loss were significantly increased. Analysis of the results showed that in both new and old roads, the treatment of JC is superior. This treatment has reduced soil loss by 9.68 times compared to CP treatment. The treatment of JC compared to the MC on a new cutslope and an old one has reduced soil loss by 2.77 and 2.54 times. Also, JC have reduced soil loss by 2.67 times compared to the MC. The total cost per square meter of JC is US $ 0.21 and this amount is equivalent to $ 0.26 for the MC. According to the results, it is suggested that soil protection and bioengineering designs should be focused on the use of JC.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 172〈/p〉 〈p〉Author(s): C. Marty, D. Houle, F. Courchesne, C. Gagnon〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Significant relationships have been observed between soil N isotopic natural abundance (δ〈sup〉15〈/sup〉N) and both climate and soil characteristics across a large range of ecosystems over the globe, suggesting strong and consistent effects of these variables on N cycling. However, whether the strength and the nature of these relationships vary at regional scales and with soil depth is less documented, especially in northern cold and N-limited forest ecosystems. In this study, we analyzed δ〈sup〉15〈/sup〉N in soil horizons at 21 forest sites in eastern Quebec along a gradient of concomitant decreasing N deposition and temperature (MAAT) and increasing precipitation (MAP). We hypothesized that both soil δ〈sup〉15〈/sup〉N and the magnitude of increase in soil δ〈sup〉15〈/sup〉N would decrease along this gradient, in accordance with relationships reported at a global scale. The data show an increase in δ〈sup〉15〈/sup〉N with soil depth, although it remained constant or sharply decreased between the B- and the C-horizon at most sites. The natural abundance of 〈sup〉15〈/sup〉N in the forest floor (FF), in the B-horizon and in the C-horizon averaged 2.2 ± 0.9‰, 6.2 ± 1.2‰ and 4.9 ± 2.0‰, respectively while total soil profile δ〈sup〉15〈/sup〉N ranged from 3.8‰ to 7.4‰. Contrary to our hypothesis, soil δ〈sup〉15〈/sup〉N was poorly correlated with climate, vegetation and most soil metrics. As a consequence, there was no spatial gradient in soil δ〈sup〉15〈/sup〉N values and in the magnitude of increase in δ〈sup〉15〈/sup〉N with soil depth across the study area. Soil C:N ratio was the only variable significantly correlated with soil δ〈sup〉15〈/sup〉N. Multivariate models including the C:N ratio explained 47%, 60% and 36% of the inter-sites δ〈sup〉15〈/sup〉N variation in B-horizon, C-horizon and total soil, respectively. In contrast with global scale studies, which have reported higher soil δ〈sup〉15〈/sup〉N at sites with low soil C:N ratio, the relationship between these two variables was positive across the study area. The possible influence of ecto-myccorhizal association on this pattern is discussed. Overall, our data show that soil δ〈sup〉15〈/sup〉N is controlled by complex mechanisms influenced by several variables with potential antagonist effects. Climate and most soil metrics appear to have no direct influence in the cold and N-limited forest ecosystems studied here and soil C:N ratio can affect soil δ〈sup〉15〈/sup〉N in an opposite manner to what has been commonly observed.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 172〈/p〉 〈p〉Author(s): Hongxi Liu, Xueqing Yang, Sergey Blagodatsky, Carsten Marohn, Feng Liu, Jianchu Xu, Georg Cadisch〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The role of weeds in soil conservation in agroforestry systems has been largely ignored. We used the Land Use Change Impact Assessment (LUCIA) model to simulate the effects of weed management on erosion in rubber plantations (〈em〉Hevea brasiliensis〈/em〉 Muell. Arg). In order to quantify the impact of a dynamic, spatially explicit multi-layer plantation structure on erosion processes in agroforestry systems, we updated LUCIA's erosion module. Its new version simulates soil detachment due to rainfall and runoff, considering the separate effects of the tree canopy and surface cover on soil erosion. The updated LUCIA model was calibrated and validated based on an established rubber plantation experiment in Xishuangbanna, Southwest China, to evaluate the impact of different weeding strategies on soil loss. The model successfully represented the impact of the dynamic multi-layer structure on erosion and was able to predict well the effects of weed management on soil loss and runoff at the test site over 1 year, with a modelling efficiency (〈em〉EF〈/em〉) of 0.5–0.96 and R〈sup〉2〈/sup〉 of 0.64–0.92. Subsequently, we validated the ability of the model to simulate surface cover changes under rubber plantations of different age (up to 40 years). Simulation outputs for 4-, 12- and 18-year-old rubber plantations revealed satisfying to good results. However, the predicted change in surface cover for old rubber plantations (25- and 36-year) failed to meet the field trends. The model predicted the greatest erosion in the year when the rubber canopy started to close. During this period, weed growth was limited by light, while litter input from rubber was insufficient to provide good soil cover. Four weeding strategies (“clean-weeding”, “twice-weeding”, “once-weeding” and “no-weeding”) were designed for scenario simulations. Based on the results of 20-year runs, we concluded that “once-weeding” and “no-weeding” both efficiently minimized soil loss during one rotation length. A high degree of surface and weed cover (over 95% and 60%) under “no-weeding” makes this management strategy with dense undergrowth hardly acceptable by local farmers due to reduced tree accessibility for tapping and increased potential danger through poisonous caterpillars. “Once-weeding”, on the other hand, controlled overgrowth of understory vegetation by keeping weed cover below 50%. We therefore suggest “once-weeding” as an improved herbicide management strategy in rubber plantations, to meet ecological system service maintenance and to facilitate adoption in practice.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 172〈/p〉 〈p〉Author(s): Gabriel P. Lobo, Carlos A. Bonilla〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Soil loss models are useful tools for making land management decisions to prevent soil and water quality problems. Several soil loss models have been developed, including the process-based Water Erosion Prediction Project (WEPP) model and the empirical Revised Universal Soil Loss Equation (RUSLE). Although process-based models provide accurate soil loss estimates, they are infrequently used for conservation planning because of their complexity and data need. On the other hand, models such as RUSLE cannot predict the soil loss nor the sediment composition associated with individual events, both of which are critical for designing accurate soil and water conservation practices. Therefore, the objective of this study was to develop a model for estimating sediment delivery on an event scale while predicting its clay, silt and sand fractions. For this purpose, the WEPP model was implemented using measured soil and climate data from Central Chile to generate a soil loss database for many hillslope configurations and management practices. More than 200,000 erosion events were generated using data from 83 sites. Using multiple regression analysis, the main variables controlling soil loss were identified, which included rainfall erosivity, soil erodibility, hillslope geometry, antecedent soil moisture and total precipitation. These variables were incorporated into a soil loss model, which was calibrated using data from 32 sites (R〈sup〉2〈/sup〉 = 0.81–0.83) and validated for the remaining 51 sites (R〈sup〉2〈/sup〉 = 0.66–0.89). The model provided accurate estimates for the clay and silt fractions (R〈sup〉2〈/sup〉 = 0.86 and 0.78, respectively) but showed difficulties for predicting the sand fraction (R〈sup〉2〈/sup〉 = 0.31). Contour plowing and vegetative filter strip routines were also incorporated into the soil loss model, providing reliable soil loss (R〈sup〉2〈/sup〉 = 0.51–0.78), clay (R〈sup〉2〈/sup〉 = 0.54–0.75), and silt (R〈sup〉2〈/sup〉 = 0.57–0.68) estimates. The developed model is remarkably easy to use and, due to its simplicity, allows incorporating other soil conservation routines, providing a flexible tool for soil conservation planning. This study provides a detailed description and methodology for building such a model and discusses its advantages and limitations.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 172〈/p〉 〈p〉Author(s): Paolo Tarolli, Marco Cavalli, Roberta Masin〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In the last decade, conservation agriculture (CA) has received particular attention from both governmental and non-governmental organizations. CA aims to achieve sustainable agricultural production. The principles of CA include minimal soil disturbance, permanent soil cover derived from crop residues or cover crops, and crop rotations that benefit soil and water conservation. Agricultural practices influence the micro-topography and modify the surface roughness, altering several important processes such as infiltration, water storage depression, and soil water erosion. In this work, we explore the effectiveness of high-resolution topography in characterizing no-tillage (NT) versus conventional tillage (T) surface morphology in order to better understand the hydro-geomorphic processes associated with these crop systems. High-resolution (2 cm) Digital Elevation Models (DEMs), derived using the Structure from Motion (SfM) photogrammetric technique, were processed for six plots (3 cultivated with NT, 3 with T) in a clay loam soil. The study area is located in northeast Italy. Several morphometric terrain parameters (e.g., connectivity, curvature and relative elevation attribute), were computed for each plot. The analysis provided challenging insights: compared to T, surfaces in the NT plots were rougher, had more pronounced slopes and curvatures, sediments with a widespread connection to the plot boundaries, had more irregular flow paths, and had a higher water storage potential due to surface concavities. This can be translated into a surface morphology that can significantly affect surface runoff, sediment transport, and the off-site movement of agricultural chemicals.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 172〈/p〉 〈p〉Author(s): Ryunosuke Tateno, Chikae Tatsumi, Masataka Nakayama, Koichi Takahashi, Dorsaf Kerfahi, Jonathan Adams〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Little is known of the earliest stages of soil ecosystem development on volcanic ash, and how this process is affected by temperature. We studied the first three years of soil development in a field-based mesocosm experiment, situated in different climates across Japan. Newly fallen, sterilized volcanic ash from the Sakurajima volcano (Kyushu, Japan) was placed into pots and positioned at six locations with mean annual temperatures ranging from - 1.6 °C to 18.6 °C. At 24 months into the experiment, C and N accumulation showed only a weak linear correlation with temperature, but by 36 months there was a clear exponential relationship. This applied only to the top 2 cm of the developing soil, and was not apparent in the lower part of the ash. We suggest that this acceleration in warmer climates relates to a positive feedback involving bryophyte cover, which had become much denser by the third year in the warmer sites. Surprisingly, the abundance of 16S rRNA gene copies of bacteria, fungi, archaea - as well as ammonia oxidizers – did not increase from 12 months to 36 months, and did not show any relationship to temperature, suggesting that input from plants is the major factor in increasing C and N buildup in the soil. Overall it appears that temperature effects on bryophyte cover buildup may be important in controlling the temperature relationship in soil development on volcanic ash.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 172〈/p〉 〈p〉Author(s): Jaume Boixadera, Irene Esteban, Rosa M. Albert, Rosa M. Poch〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉Raised field cultivation (〈em〉camellones〈/em〉) is a Pre-Columbian technique, now abandoned, which is very extensive in the Llanos de Moxos (Bolivia). The objectives of the research were to understand the effects of human actions on the morphology, genesis and characteristics (especially redoximorphic features and chemical properties) of these soils on ridged fields and their past use. We studied five representative raised field (anthropogenic) soils and other non-anthropogenic soils around San Ignacio de Moxos and along the transect Trinidad-San Borja.〈/p〉 〈p〉The non-anthropogenic soils are acidic, show a wide range of clay contents and different degrees of human activity according to their available phosphorus content. Soil-forming processes are related to fine fraction mobility and alternating redox conditions. Contrarily, the soils of the raised fields show a distinct pattern of redoximorphic features from ridge to channel. Moreover, ridges tend to be less acidic and have lower aluminium saturation than channels. Nevertheless, they have neither artifacts nor charcoal, and their colour and P content is similar to those of surrounding soils.〈/p〉 〈p〉The raised fields appear to have been built to improve the drainage conditions. Chemical soil fertility was not the main issue and they were used for cultivation including maize. The set of characteristics encountered (differences in pH, and drainage status at a microscale) should be used to improve the classification of these anthropogenic soils.〈/p〉 〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 172〈/p〉 〈p〉Author(s): Feng Gao, Yunpeng Wang, Xinyi Hu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Three different empirical models based on Landsat, MERIS, and MODIS sensors were used to retrieve TSM concentrations and construct long-term TSM image datasets during the period from 2003 to 2011. These datasets were utilized to evaluate the suitability of Landsat, MERIS, and MODIS for identifying spatial distribution patterns of TSM concentration based on a self-organizing map (SOM) algorithm in the Pearl River Estuary (PRE). 12 spatial distribution patterns of TSM in the PRE were identified from long-term TSM data of each sensor based on a 4 × 3 SOM array. The expected frequency of occurrence of any given pattern and relative frequency of occurrence of each pattern were calculated and analyzed. The factors that influence the variability of TSM and the spatial distribution patterns of TSM were explained by the contribution of human activities, precipitation, and characteristics of satellite sensors. Our results showed that similar spatial distribution patterns of TSM were extracted from three different TSM image datasets. Each pattern presented a strip distribution from northeast to southwest, and the values of TSM decreased regularly from northwest to southeast. However, patterns identified from Landsat and MODIS TSM images presented some anomalous patterns, which were inconsistent with local circumstances and previous studies. High (low) level spatial distribution patterns of TSM in the SOM array were associated with a variety of high (low) values of TSM concentration in the PRE. Frequency analyses of each pattern demonstrated that notable differences of TSM concentration existed in the PRE from 2003 to 2011. These findings can assist us to better understand the dynamics of TSM concentration and the performance of different empirical models established by Landsat, MERIS, and MODIS for identifying spatial distribution patterns of TSM concentration using the SOM algorithm.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 172〈/p〉 〈p〉Author(s): Archimedes Perez Filho, Felipe Gomes Rubira〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The research seeks to explain the use of Optically Stimulated Luminescence (OSL) and highlight the importance of this method for the evolutionary interpretation of tropical quaternary landscapes through systematic geochronological reconstitutions of a pedogeomorphological nature. To this end, studies that used OSL and corroborated the geochronological evolution of tropical landscapes were evidenced. Emphasis was given to Brazilian studies conducted in the state of São Paulo, in the Western Plateau and Peripheral Depression, that addressed the relationship between fluvial and planation surfaces (geomorphological systems) and their surface coverings, in addition to Holocene climatic pulsations, associating them with landforms and deposition processes of surface coverings. Such surveys showed recent erosive/depositional events, responsible for imposing new dynamics on pedogeomorphological systems. At the same time, they were able to establish regional morphoclimatic scenarios to review former geomorphological proposals based on relative dating and relatively subjective hypotheses. OSL was important and has undeniably contributed to the enhancement of evolutionary theories; the identification of Holocene climatic pulsations that lead to hot and wet periods (5.300–6.200, 4.200–4.600, 2.000–2.400, 800–1.200 and 0–400 years B·P.), interrupted by hot and dry periods (7.900–10.000, 6.200–6.600, 4.600–5.300, 2.400–4.200, 1.200–2.000, 400–800 years B·P.), resulting from global cooling events; the building of a geochronological database (ages); and the innovation of geomorphological knowledge regarding surface coverings of geomorphological surfaces in tropical climates.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 173〈/p〉 〈p〉Author(s): Farzin Shahbazi, Philip Hughes, Alex B. McBratney, Budiman Minasny, Brendan P. Malone〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Soil legacy data is ubiquitous and usually contains routine soil analysis information. In Iran, like most places, legacy soil data constitutes genetic horizon soil information recorded from excavated soil profiles. Describing and sampling from each genetic horizon is assumed to be heterogeneous from site to site. Digital soil mapping (DSM) using observed data is valuable because it provides a means to exploit the available information together with leveraging commonly available information by way of environmental covariates. It creates a much more detailed view of soil at the landscape scale. The purpose of this paper is to model and map the spatial distribution of nitrogen, phosphorous and boron at four standardized depths: 0–15, 15–30, 30–60, 60–100 cm, in an area of 7300 ha in the north west of Iran, and compare different model types. To circumvent the issue of heterogeneous soil depth observations from site to site, mass-preserving soil depth function splines were used to harmonise the soil profile observed data to the aforementioned standard depths. This facilitated the spatial modelling of each of the target variables for each standard depth with the aim of creating digital soil maps. Twenty-three covariates were extracted from a publically available digital elevation model (DEM) as well as freely available Landsat 8 ETM〈sup〉+〈/sup〉 imagery. The DEM-derivative covariates used in this study were divided into three main categories: i) Morphometry; ii) hydrology; and iii) lighting visibility. Both Random Forest and Cubist were assessed as candidate models for predicting each target variable. The results showed that Cubist was the most accurate method. Terrain attributes play an important role in estimating N, P, and B, while optical images do not have significant role. The most important findings of this paper in terms of environmental hazards are that the inundated regions in the west part of the study area are susceptible to boron contamination, providing future guidance for remediation.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 172〈/p〉 〈p〉Author(s): 〈/p〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 172〈/p〉 〈p〉Author(s): Ekrem Lutfi Aksakal, Kenan Barik, Ilker Angin, Serdar Sari, Khandakar Rafiq Islam〈/p〉 〈div xml:lang="tr"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Soil physical properties play an important role in determining soil's suitability for agricultural uses. The purpose of our study was to characterize spatio-temporal variations in moisture content (θ〈sub〉m〈/sub〉), bulk density (ρ〈sub〉b〈/sub〉), aggregate stability (AS) and penetration resistance (PR) of different textured soils under similar management and climatic conditions. A 25 × 25 m area was monitored in each of the 3 fields with Daphan clay (Haplustert), Ciftlik loam (Fluvaquent), and Ciftlik sandy loam (Ustorthent) from September 2014 to August 2015. Each area was divided into 5 × 5 m cells. Undisturbed soils from 0 to 10 cm depth at 36 intersection points were collected monthly, and processed and analyzed. Results showed that spatio-temporal changes in soil properties were strongly affected by natural freezing-thawing and wetting-drying processes. While the θ〈sub〉m〈/sub〉 increased with rainfall and/or snow melts through September–January, the θ〈sub〉m〈/sub〉 decreased onwards February. The θ〈sub〉m〈/sub〉 ranged between 11.50 and 56.34% for the Daphan clay, 7.26 and 41.92% for the Ciftlik loam, and 2.52 and 33.83% for the Ciftlik sandy loam, with highest variabilities in January and November, and the lowest variabilities in July and August. The decrease in θ〈sub〉m〈/sub〉 was closely and linearly associated (r = −0.94〈sup〉⁎⁎〈/sup〉) with ρ〈sub〉b〈/sub〉 and vice versa. However, the temporal variation in AS was primarily due to θ〈sub〉m〈/sub〉 and its effects on freezing-thawing and swelling/shrinking during wetting-drying cycles. While the lowest AS was measured in February, the highest AS was observed in July for the Daphan clay, and August for the Ciftlik loam and Ciftlik sandy loam, respectively. The AS linearly and inversely related to θ〈sub〉m〈/sub〉 (r = −0.66〈sup〉⁎⁎〈/sup〉). Likewise, the PR decreased linearly with an increase in θ〈sub〉m〈/sub〉, and vice versa. While the θ〈sub〉m〈/sub〉 linearly decreased the PR (r = −0.45〈sup〉⁎⁎〈/sup〉), the ρ〈sub〉b〈/sub〉 increased PR (r = 0.45〈sup〉⁎⁎〈/sup〉). Results suggested that spatio-temporal variations in core soil physical properties could provide useful information for site-specific precision agricultural management practices to improve soil quality.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 172〈/p〉 〈p〉Author(s): Amobichukwu C. Amanambu, Lanhai Li, Christiana N. Egbinola, Omon A. Obarein, Christophe Mupenzi, Ditao Chen〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Spatio-temporal variation in rainfall-runoff erosivity resulting from changes in rainfall characteristics due to climate change has implications for soil and water conservation in developing countries. Understanding past and future variations in rainfall-runoff erosivity and its implication, in tropical areas where there are limited continuous daily rainfall records, is important. The present study attempted to (i) quantify the nature of spatiotemporal variability of erosivity from rainfall amount using Global Circulation Models (GCMs), and (ii) evaluate the implications of changes in rainfall-runoff erosivity in the Lower Niger Basin, West Africa. The GCMs scenarios (GFDLCM3, HADCM2, MIROC5, and MPIESMLR) were statistically downscaled using the delta method for three-time slices (the 2030s, 2050s, and 2070s). World climate data was used as the current baseline climate since it is the source of the future precipitation simulation. The R factor from the Revised Soil Loss Equation (RUSLE) was used to determine erosivity, while the RUSLE model was used to ascertain the implications of changes in erosivity. Observation data (1970–2013) from 20 meteorological stations were used to validate the erosivity model. The result indicates that there is an increasing trend in the annual rainfall-runoff erosivity from the baseline climate up to the GCMs, for all the GCMs, with an average change in rainfall-runoff erosivity of about 14.1%, 19%, and 24.2% for the 2030s, 2050s, and 2070s respectively. There was a concomitant increase in soil loss of 12.2%, 19.3% and 20.6% from the baseline for the 2030s, 2050s, and 2070s respectively. Though the combined average annual rainfall and erosivity show steady increases, some of the models (GFDLCM3-2.6 and HADCM2-2.6) reveal a likely decrease in annual rainfall and erosivity for the 2070s. Higher precipitation amounts were the major drivers of increasing spatial and temporal rainfall-runoff erosivity. More studies should be performed to include other important factors that exacerbate increases in erosivity, especially future changes in land use.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 172〈/p〉 〈p〉Author(s): Remus Prăvălie, Adrian Piticar, Bogdan Roșca, Lucian Sfîcă, Georgeta Bandoc, Adrian Tiscovschi, Cristian Patriche〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Changes in precipitation (P), evapotranspiration (ET) and, implicitly, in the climatic water balance (CWB), are imminent effects of climate warming. However, changes in the CWB, as a response to changes in P and ET, have not yet been analysed thoroughly enough in many parts of the world, including Romania. The present study explores the spatio-temporal changes of the CWB (difference between P and reference evapotranspiration, ET〈sub〉o〈/sub〉) in Romania, based on a wide range of climatic data (P, as well as temperature, relative air humidity, sunshine duration and wind speed, necessary for computing ET〈sub〉o〈/sub〉 with the FAO-56 Penman-Monteith method) recorded at 70 weather stations across the country in the 1961–2013 period. As a secondary objective, the study attempts to identify the possible connections between the index's trends and large-scale atmospheric circulation, assessed based on the dynamics of certain European-scale relevant teleconnection indices. Thus, the Mann–Kendall test and 〈em〉Sen's slope〈/em〉 methods were used to analyse CWB trends (but also P and ET〈sub〉o〈/sub〉 trends, in order to explain CWB pattern changes) annually, seasonally and in the maize and wheat growing seasons. Also, the Spearman correlation procedure and a composite analysis between interannual series of teleconnection indices and CWB were used to assess the influence of atmospheric circulation on the index's variability for all analysed time scales. The results generally showed CWB decreases (for the most part of up to −2 mm/yr, yet with a relatively low statistical significance) and highlighted an overall amplification of drier conditions on all time scales, except for autumn (CWB increases, generally of up to 1 mm/yr, but with low statistical significance). Moreover, net changes of even under −200 mm/53 yrs annually and −175 mm/53 yrs in summer and for the maize and wheat growing seasons were found in the CWB. Spatially, it was found that the country's southwestern and southeastern regions are the main epicentres of drier trends, while the northwest appears to have become wetter. Overall, the negative CWB trends are due to partial P decreases (statistically insignificant) and general ET〈sub〉o〈/sub〉 increases (highly statistically significant, even 100% in summer). It seems that the amplification of the climatic water deficit across the country is especially linked to the positive phases of the Arctic Oscillation and North Atlantic Oscillation, but also, in part, to those of several other teleconnection indices that affect Europe. Our results signal the necessity to adapt anthropic and ecological systems to future dryness trends countrywide, which will most likely intensify against the background of climate change expected to occur by the end of the century.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 172〈/p〉 〈p〉Author(s): Jiaorong Lv, Han Luo, Yongsheng Xie〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Spoil heaps are the main sources of soil erosion on disturbed land surfaces as an artificial accelerated erosion form, and rock fragments are an important component of spoil heaps. This study examined different fragment contents (0, 20, 40, 60 mass percentage) and sizes (1–4, 4–7, 7–10 cm) on hydrological processes, sediment yielding processes and rock fragment cover evolution through three sequential simulated rainfalls with a constant intensity of 1.5 mm min〈sup〉−1〈/sup〉. The rock fragments in spoil heaps were found to reduce the soil loss amount by 35.23–76.84% through effects on runoff production and rock fragment cover. Runoff rates decreased with increasing rock fragment content, and size class 4–7 cm had the strongest reduction effect, but for a definite treatment runoff rates have little change in three rainfall events. The expanding rock fragment cover with cumulative rainfall in the multiple rainfall events, which increased fastest during the first rainfall period led to a significant decreasing soil detachment rate. Multiple regression analysis shows that the average detachment rate under each rainfall event could be estimated using a power function of average runoff rate and median rock fragment cover. These findings indicated that the presence of rock fragments in spoil heaps has an obvious mitigating effect on soil erosion, with the rock fragment content making a larger percentage contribution than rock fragment size.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 172〈/p〉 〈p〉Author(s): P.I.A. Kinnell〈/p〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 172〈/p〉 〈p〉Author(s): Jing Yang, Hongsong Chen, Yunpeng Nie, Kelin Wang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Precipitation in the karst regions of southwest China is plentiful, however, soils are shallow and highly permeable, which results in rapid transportation of surface water through a soil profile. Therefore, the presence and amount of water stress in a soil layer can be unpredictable. This study will investigate the soil water conditions on karst hillslopes in southwest China through dynamic in situ observations of profile soil moisture (〈em〉θ〈/em〉). Three profiles at two slope positions on two shrub-grasslands (S1 and S2) were selected, respectively. At each profile, TDR 100 probes were set at 10, 20, 30, 50, and 70 cm and for 100 cm, only on downslopes. Soil samples (undisturbed and disturbed) were collected to measure basic physical and chemical properties. Precipitation and 〈em〉θ〈/em〉 were monitored manually each week between July 15, 2012 and November 25, 2014. Results show that soil properties, which have an important effect on 〈em〉θ〈/em〉, varied among slope positions and between the two hisllslopes. A higher clay content, which led to greater water holding capacity, explained a higher 〈em〉θ〈/em〉 in downslopes and on S2. Shallow soil layers (0–30 cm), especially in the coarse textured soil layers of S1, were susceptible to water stress due to the limited availability of soil water. Water stress was low during water supplying (December through April) and relatively stable periods (May to June). However, during water consuming periods (July to November), profile 〈em〉θ〈/em〉 decreased greatly which resulted in severe water stress for the whole profile. Although precipitation was seasonally uneven, based on weekly observations, profile 〈em〉θ〈/em〉 on both hillslopes was not temporally active (coefficients of variation of 〈em〉θ〈/em〉 was smaller than 20%) and the variance of each depth was similar. Generally, the effects of precipitation on 〈em〉θ〈/em〉 can last two (0–50 cm) to five (70–100 cm) weeks. Nevertheless, 〈em〉θ〈/em〉 of downslope deep soil, which was (or near) saturated all year round, was barely affected by precipitation. These results can provide valuable information for hydrological models and rational strategies for ecological restoration designing in karst regions.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 173〈/p〉 〈p〉Author(s): C. Zouré, P. Queloz, M. Koïta, D. Niang, T. Fowé, R. Yonaba, D. Consuegra, H. Yacouba, H. Karambiri〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In the Sahel region, farmers have adopted various farming practices to improve agricultural yields in order to offset an increasingly variable climate regime and the extension of degraded land. This study analyses the functional behaviour of such three selected water-harvesting techniques (stone rows, zaï and half-moon) as compared to the traditional tillage method through a comprehensive experimental setup monitored during three consecutive growing seasons (2015–2017). The results indicate that these farming practices allow a runoff reduction by 25 to 100%. We propose a continuous model simulating the hydrological dynamics of the farming techniques at plot scale. This model is able to reproduce accurately the observed runoff (〈em〉R〈/em〉〈sup〉2〈/sup〉 = 0.73 − 0.95), and gives an insight of the variability of the water storage for each type of techniques in response to the rainfall regime. It appears in particular that zaï and half-moons are able to mitigate the effect of dry spells by sustaining available water for crops over extended periods up to three weeks, whereas the direct seeding and stone row techniques rapidly leads to plant water deficit after five days. Even though water infiltration is essentially fostered by surface water retention during rainfall events, our observations suggest that the changes induced to the hydrological dynamics by farming practices also affect soil physical, chemical and biological properties. These effects help completing the explanation of crop yield improvements, but raise some questions of soil evolution and farming practice performances in the long run.〈/p〉〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 172〈/p〉 〈p〉Author(s): Selma Yaşar Korkanç, Gamze Dorum〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉Nutrient losses constitute an important issue for the protection of both soil and water resources. Organic carbon transport is also important for the global carbon cycle. In this study, it was aimed to determine the amount of nutrients and the total organic carbon which was transported by surface runoff water formed under simulated rainfall conditions from areas with different land cover systems.〈/p〉 〈p〉Accordingly, 3 cultivated areas having various product patterns under similar conditions (potato field (P), bean-cultivated area (B), abandoned farmland covered with 〈em〉Noaea〈/em〉 sp. (AB)), 2 plantation areas (cedar (C) and almond (AL)) and 2 rangelands covered with 〈em〉Thymus〈/em〉 sp. (T) and 〈em〉Stipa〈/em〉 sp. (S) were chosen for performing applications. The applications were performed in two repetitions on 0.28 m〈sup〉2〈/sup〉 circular experimental plots established in the above-mentioned areas. The collection of surface runoff was performed during land applications. The pH, electrical conductivity, nitrate (NO〈sub〉3〈/sub〉〈sup〉−〈/sup〉), ammonium (NH〈sub〉4〈/sub〉〈sup〉+〈/sup〉), total phosphorus, orthophosphate (PO〈sub〉4〈/sub〉〈sup〉3−〈/sup〉), total organic carbon (TOC), and total nitrogen (TN) parameters of surface runoff water were measured. The land cover change affects total nitrogen, nitrate, ammonium, pH, electrical conductivity, total phosphorus, orthophosphate and TOC parameters. Nitrate transport was found to be B 〉 P 〉 T 〉 AB 〉 C 〉 AL 〉 S from highest to lowest. Ammonium transport was B 〉 T 〉 AL 〉 C 〉 AB 〉 P 〉 S. The total nitrogen transport was B 〉 P 〉 T 〉 AB 〉 C 〉 AL. The total phosphorus transport was found to be P 〉 B = T 〉 AB 〉 AL 〉 C 〉 S. Ortho-phosphate transport was P 〉 B 〉 T 〉 AB 〉 C 〉 AL 〉 S. In terms of the TOC transport, the order was found to be T 〉 B 〉 P 〉 AB 〉 AL 〉 C from highest to lowest.〈/p〉 〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 172〈/p〉 〈p〉Author(s): Helmi Hamdi, Sarra Hechmi, Mohamed Naceur Khelil, Inès Rahma Zoghlami, Saoussen Benzarti, Sonia Mokni-Tlili, Abdennaceur Hassen, Naceur Jedidi〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The agricultural reuse of urban sewage sludge in degraded croplands has seen a wide acceptance for biowaste recycling and for the improvement of soil fertility. However, soil degradation and health issues may arise from the fact that sludge addition causes chemical and biological contamination if mismanaged. To closely monitor the long term soil-sludge interactions, a field study was conducted over a three-year period under a semi-arid climate. More precisely, changes in topsoil properties were assessed in 4-m〈sup〉2〈/sup〉 uncropped plots amended with sludge rates equivalent to 0, 40, 80 and 120 t ha〈sup〉−1〈/sup〉 year〈sup〉−1〈/sup〉 for two soil textures: soil A (sandy loam) and soil S (sandy). Results showed that all studied parameters changed significantly in a dose-dependent manner for both soils as compared to untreated controls. As such, sludge addition improved consistently TOC, N, P and K content up to soils treated with 120 t ha〈sup〉−1〈/sup〉 year〈sup〉−1〈/sup〉. The enhancement of soil nutrient status impacted positively on biological properties, including microbial biomass and soil enzyme activities (dehydrogenase, protease and phosphatase). However, the variation of soil properties was more important in soil A characterized by a higher fine fraction thus stronger retention capacity. Accordingly, XRD analysis of soil A revealed several identifiable peaks representing kaolinite and illite clays in contrast to soil S. Unexpectedly, high to excessive sludge doses of 80 and 120 t ha〈sup〉−1〈/sup〉 year〈sup〉−1〈/sup〉 did not provoke soil degradation after three repeated annual amendments. In fact, pH values in both soils remained within neutral to alkaline range (7.76–8.63); total heavy metals (Cu, Zn, Ni and Pb), soil salinity and fecal coliforms were all below threshold values for contaminated soils.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 172〈/p〉 〈p〉Author(s): K.S. Lindeburg, P.J. Drohan〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Eastern United States loess mapped by the U.S. Department of Agriculture, National Resources Conservation Service (USDA-NRCS) mostly occurs near major river systems like the Delaware and Susquehanna Rivers. The proximity of loess along major river valleys suggests late-Quaternary glacial meltwater sediments were dominant sediment sources for loess. Based on differing lithologies of meltwater deposits in these systems, we hypothesize that loess in each river system has a unique geochemical and mineralogical signature. To test this hypothesis, we examined pedons developed in loess parent materials, and adjacent to either the Delaware or West-Branch of the Susquehanna River, both of which carried large amounts of Wisconsinan outwash. Soils were analyzed for particle size distribution, clay mineralogy, and coarse and fine silt particle density, mineralogy, and geochemistry. Results show that while the pedons are similar in morphology, substantial differences exist in the pedons' textures, mineralogies, and geochemical compositions. We attribute the differences to parent material differences that stem from lithologically distinct sediment sources for loess from the two river systems. Susquehanna River loess has a higher particle density, and lower abundance of minerals such as Zr, base oxides (such as CaO), and rare earth elements. Discriminant analysis results suggest that developing a “loess fingerprint” for each river system based on major, minor and rare earth elements is possible, and likely to be useful in differentiating sources; however coarse silts may be a more effective fraction (than fine silts) for sediment sourcing, especially if rare earth elements are used.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 172〈/p〉 〈p〉Author(s): Antonella Colica, Marco Benvenuti, Laura Chiarantini, Pilario Costagliola, Pierfranco Lattanzi, Valentina Rimondi, Massimo Rinaldi〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉Fluvial sediments of the Paglia River, a tributary of Tiber River (Central Italy), are contaminated by mercury (Hg) as a consequence of past mining activity (1846–1981, with main production 1900–1970) in the Monte Amiata district (the 3rd largest Hg producer worldwide). In this study, we combine a geomorphological analysis with geochemical data to try and understand the influence of fluvial dynamics on the spatial distribution of Hg in fluvial sediments over a 43 km segment of the river.〈/p〉 〈p〉By considering the evolution of the river course between 1883 and 2013, eight different geomorphic units (GUs) were recognised, including the active channel bed (baseflow channel and bar), the floodplain, and five orders of terraces. The distribution of Hg in sediments of these GUs reflects the timing of their formation with respect to evolution of the mining activity. In GUs formed before the main peak of mining activity, or after mine closure, sediments show mean Hg contents comparable to, or slightly higher than, the local background, estimated at 2–6 mg/kg; in GUs formed during the peak production, Hg mean contents are definitely higher (up to 26 mg/kg). The current floodplain also shows high contents (mean 19 mg/kg), because of continuous reworking and transport of older contaminated sediments during major flood events. Therefore, the point contaminant sources represented by mining centres evolved into a diffuse source spread over several tens of kilometres.〈/p〉 〈p〉By combining geochemical data with calculated sediment volumes, we estimate that not less than 63 tonnes of Hg are currently contained in the sediments of the investigated river stretch. Such amount of Hg will probably limit for the near future a full land use along the Paglia–Tiber course.〈/p〉 〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0341816218303679-ga1.jpg" width="301" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 172〈/p〉 〈p〉Author(s): Abbas Miri, Deirdre Dragovich, Zhibao Dong〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉To develop our knowledge of the impact of different vegetation types on aeolian sand flux, a series of experiments conducted in a wind tunnel monitored sand mass flux over a bare surface and in relation to the planted surface of two types of live plants, 〈em〉Cosmos bipinnatus〈/em〉 and 〈em〉Ligustrum lucidum Ait〈/em〉, at different plant densities. Normalized sediment flux decreased with increasing height over a bare surface. However, plants affected the sediment transport system by modifying the vertical distribution of sediment flux within and above the vegetated surface. Sand flux reduced from low to high plant density below the plant height but this pattern reversed above the vegetated surface. Observations of the horizontal profiles of sand flux indicated sediment was transported within the vegetated areas of both plant types in all densities. In low density, the horizontal trend of sand flux was similar to the bare sand surface. In medium density, the sand flux increased slightly within the vegetated surface and decreased beyond the vegetated surface for both plant types. In high density, sediment flux increased from the upwind edge to the middle of the vegetation barrier, and reduced at the downwind end and beyond the vegetated surface of both plant types. Observations of sand flux in different plant densities revealed the influence of plant drag versus the turbulence produced by plants. At a certain distance within the vegetated area, plant drag reduced the sand flux. Although varying between the two plant types, sand flux decreased overall from unplanted to planted configurations.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0341816218303746-ga1.jpg" width="402" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 174〈/p〉 〈p〉Author(s): Xu Chen, Qianglong Qiao, Suzanne McGowan, Linghan Zeng, Mark A. Stevenson, Lei Xu, Chunling Huang, Jia Liang, Yanmin Cao〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Accurate chronologies for recent sediments of shallow lakes in the Yangtze floodplain are critical to calibrate proxy records for reconstructing environmental changes during the past century. This study presents the results of detailed 〈sup〉210〈/sup〉Pb analysis from eight lake sediment cores collected from the middle Yangtze reaches, southeast China. Unsupported 〈sup〉210〈/sup〉Pb activities generally declined exponentially with mass depth in the eight cores. The chronologies and sedimentation rates for the sediment cores were calculated using different 〈sup〉210〈/sup〉Pb-based mathematical models. The 〈sup〉137〈/sup〉Cs chronomarker (i.e. the 1963 fallout peak) and the spheroidal carbonaceous particle (SCP) chronomarker (i.e. the start of the rapid increase in 1970 CE) were selected to validate the 〈sup〉210〈/sup〉Pb dating. Sedimentation rates derived from different models were validated using historical data including lake area, arable land area, sediment discharge and reservoir volume in the Yangtze basin. The SCP-corrected CRS (constant rate of supply) model performs better than other models, based on validation using historical documents in the Yangtze basin. The 〈sup〉137〈/sup〉Cs chronomarker might be erroneous due to catchment-driven 〈sup〉137〈/sup〉Cs inputs from soil erosion and post-depositional diffusion. Both SCPs and 〈sup〉137〈/sup〉Cs are susceptible to inputs from catchment soil erosion, but SCPs show no apparent degradation and post-depositional changes in lake sediments. The SCP profile provides a relatively reliable chronomarker, which can be used for validating 〈sup〉210〈/sup〉Pb chronologies in these floodplain lakes. Generally, sedimentation rates in the eight lakes were 〈0.2 g cm〈sup〉−2〈/sup〉 yr〈sup〉−1〈/sup〉 before the 1930s, and then increased to a peak in the 1960s. Afterwards, sedimentation rates decreased and remained low after the 1980s.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0341816218305368-ga1.jpg" width="366" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 174〈/p〉 〈p〉Author(s): Romain Reulier, Daniel Delahaye, Vincent Viel〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Agricultural activity evolution during the second half 20th century has profoundly changed agricultural landscapes in western Europe. Numerous scientific studies have shown that the consequences on erosive runoff processes are important. This study aims show one of the important consequences of these transformations that is the structural connectivity between cultivated plots and the river. The study is based on the analysis of aerial images taken at four different dates (1947, 1967, 1988 and 2014) and on the use of the LASCAR (LAndscape StruCture And Runoff) multi-agent model. It shows how agricultural landscapes have evolved over the past 70 years and how this has altered the connectivity of cultivated plots to the river. In addition to the development of spatial analysis indices, the results of this study offer key understandings relevant to all spatial scales (global to local). The study was carried out on a small agricultural watershed in the northwest of France (Lingèvres, 17.6 km〈sup〉2〈/sup〉), whose recent landscape evolution is part of the overall dynamics of northwest French agricultural landscapes transformation.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: April 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 175〈/p〉 〈p〉Author(s): Han Luo, Yubo Rong, Jiaorong Lv, Yongsheng Xie〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Overburdened stockpiles during construction projects are typically loose mixtures with different proportions of fines and gravel. They are common sources of anthropogenic accelerated erosion that threatens environmental quality and the quality of life for people in many parts of the world. Overburdened stockpiles have unique three-dimensional shapes. However, studies with these materials are usually performed in traditional planar soil bins. Therefore, in this study, a specially designed mobile experimental device was used to accurately evaluate the runoff erosion process on overburdened stockpiles in a three-dimensional conical shape. A series of indoor rainfall simulation experiments at 60 mm/h rainfall intensity was conducted using material with different gravel contents (0%, 10%, 20%, 30%, and 40%). The results showed that the runoff rate and flow velocity exhibited the same trend, i.e., a rapid increase, followed by a slow increase and then stabilization. The runoff regime in all experiments manifested as laminar and subcritical flow during the runoff process. 〈em〉Re〈/em〉 and 〈em〉Fr〈/em〉 values were much smaller than those on two-dimensional plane simulation of overburdened stockpiles. The presence of gravel caused the runoff to be slow and stable. Runoff rate, flow velocity, 〈em〉Re〈/em〉 and 〈em〉Fr〈/em〉 values all decreased with increasing gravel content. The sediment yield decreased logarithmically in response to the increasing gravel content. The study findings are not only helpful for understanding the hydraulic characteristics and erosion features that characterize overburdened stockpiles, but also have implications for prediction models of soil and water loss from this material during production and use in construction projects.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 174〈/p〉 〈p〉Author(s): Silvana Moragues, M. Gabriela Lenzano, Stella Moreiras, Andrés Lo Vecchio, Esteban Lannutti, Luis Lenzano〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We present results of the estimation of surface changes associated with slope instability processes on the Upsala Channel by remote sensing and statistic techniques. Hillslopes, involving lateral moraines, of Upsala Channel at the Argentino Lake have become potentially unstable due to the retreat of Upsala Glacier during the last century. The glaciation and deglaciation processes modify the tensions on the slope stability and may generate landslide processes. A landslide movement destroyed the western edge of the Upsala Channel in February 2013. In addition, the region represents a great tourist attraction usually ships navigate through the Upsala Channel seeing impressive landscapes, especially the Upsala Glacier, stand out. Due to this risky situation the necessity of increasing the knowledge in the area has arisen but has not been addressed yet. Therefore, the main goal of the present study is to investigate the multivariate statistical techniques by the principal component analysis (PCA) and discriminative analysis (DA) in four testing areas (TAS〈sub〉〈em〉n〈/em〉〈/sub〉). Besides, we include Pearson's correlation coefficient (PCC) and normal distribution (ND) to determine whether the testing areas suffered slope movements or were temporally stable. The study is based on Landsat optical satellite images, acquired during the period from October 2001 to April 2015. The results show that TAS〈sub〉1,2,4〈/sub〉 are less stable, whereas TAS〈sub〉5〈/sub〉 is a more stable area as compared to another TAS. The PC1 and PC2 principal components explained the total variability of the 76% data. The total apparent error of DA reached 2.2% points. The PCC achieved a positive trend during the years when movement on the slope surface was not observed; while during the periods when slope instability was observed, the correlation showed a negative trend. The TAS〈sub〉〈em〉n〈/em〉〈/sub〉 that had shown a different behavior presented contrasted Gaussian bells; they are more flattened in those years with instability events.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 174〈/p〉 〈p〉Author(s): Ana I. Casalini, Pablo J. Bouza, Alejandro J. Bisigato〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Ecotonal boundaries are often arranged by following topoedaphic gradients. Despite its relevance, the interrelationships between vegetation and geomorphology have not been adequately documented in most arid regions. The Southern Monte – Patagonia ecotone, defined by anastomosing systems of paleochannels and paleobars, presents an opportunity to study these interrelationships. Our aim was to determine whether topography and/or soil characteristics explained the distribution of communities which are typical of both Phytogeographic Provinces. Vegetation and soil surveys were performed along topographical gradients found between several paleochannels and paleobars. Surface soil texture, organic carbon, total nitrogen, carbonate content and electric conductivity were measured at each site. Digital elevation models and moisture index maps were derived from topographical field data. Soil and plant cover differences between landforms were inspected. Afterwards, species distribution, communities' attributes and its relation with topographical variables were explored. Paleochannels exhibited higher shrub and total cover, as well as higher organic carbon and lower carbonate content than the paleobars. 〈em〉Chuquiraga avellanedae〈/em〉 (Asteraceae) dominated the plant community in the paleochannels, while on the contrary 〈em〉Larrea divaricata〈/em〉 (Zygophyllaceae) was the most abundant species found on the paleobars. These communities are related to Patagonia and Monte Phytogeographic Provinces, respectively. Species distribution was mainly explained by elevation and secondly by surface water redistribution. Current vegetation patterns strongly mirror the paleolandscape and as a consequence of that, plant communities are interspersed throughout the landscape. Our results emphasize the importance of geomorphology as a factor influencing community distribution along arid ecotones.〈/p〉〈/div〉 〈/div〉