ALBERT

Description: Fusarium circinatum is the causal agent of pine pitch canker (PPC), one of the most devastating forest diseases worldwide. This fungus causes severe damping-off in pine seedlings and growth reduction, wilting and the development of cankers in pine forests and plantations. A draft of the complete genome sequence of this phytopathogen was recently made available. This information was used to annotate in silico the gene Fcrho1 as a putative homolog of Rho1 GTPase genes. In this study, we generated Fcrho1 deletion mutants in two F. circinatum wildtype strains isolated from damaged trees in northern Spain. For that, we used a modified version of the OSCAR methodology, an approach not previously used in F. circinatum that allows the generation of deletion constructs in a single cloning step. The conidiation and spore germination of the resulting deletion mutants were not affected, neither the hyphal morphology. However, the mutant strains showed significantly reduced growth in vitro and more foamy macroscopic hyphal morphology than their corresponding ectopic and wildtype strains. Finally, an in vivo virulence assay showed that the reduced in vitro growth rate characteristic to the deletion mutants does not impact their pathogenicity.

Description: Operational studies are necessary to support production and management decisions of forest industries. A time study (TS) approach is widely used in timber harvesting operations to understand the performance of individual harvesting machines as well as the entire system. However, several limitations of the TS approach include the use of generalized utilization rates, incapability of capturing interactions among equipment, and model extrapolation in sensitivity analysis. In this study, we demonstrated the use of discrete event simulation (DES) techniques in modeling a ground-based timber harvesting system, and compared the DES results with those of the TS model developed with the same observed data. Although both TS and DES models provided similar estimation results for individual machine cycle times and productivities, the estimated machine utilization rates were somewhat different due to the difference in synthesizing machine processes in each approach. Our sensitivity analysis and model expansion to simulate a hypothetical harvesting system suggest that the DES approach may become an appropriate method for analyzing complex systems especially where interactions among different machine processes are unknown.

Description: The number of mixed cropland—apple orchard system has gradually increased in the Changwu Tableland region of the Loess Plateau, China. However, the soil water content (SWC) is not sufficient to maintain the sustainable development of apple trees in this agroforestry system. It is unclear whether the growing fruit trees would compete with crops for soil water. To systematically analyze the temporal and spatial distribution of soil moisture and to understand the effect of orchard hydrology in that cropland, the SWC was measured at different depths at different locations on cropland and in an apple orchard. The results show that: (1) The SWC of each soil layer in the cropland (0–20, 20–60, 60–100, 100–200, 200–300 cm) is higher than that of the orchard. The soil moisture changes dramatically in the 0–200 cm soil layer. (2) As the soil moisture monitoring distance from the apple orchard increases, the SWC gradually increases, the loss of soil water storage gradually decreases, and the drying effect gradually disappears. This is related to the different distribution ranges of the roots of apple trees and crops. Therefore, the government should control the proportion of the orchard and cropland, and then adjust the planting period of the orchard in the appropriate range to keep the green use of water in the region.

Description: Continuous research into the availability of phosphorus (P) in forest soil is critical for the sustainable management of forest ecosystems. In this study, we used sequential chemical extraction and 31P-nuclear magnetic resonance spectroscopy (31P-NMR) to evaluate the form and distribution of inorganic P (Pi) and organic P (Po) in Casuarina forest soils of a subtropical coastal sand dune in Houlong, Taiwan. The soil samples were collected from humic (+2–0 cm) and mineral layers (mineral-I: 0–10, mineral-II: 10–20 cm) at two topographic locations (upland and lowland) with different elevations. Sequential chemical extraction revealed that the NaOH-Po fraction, as moderately recalcitrant P, was the dominant form in humic and mineral-I layers in both upland and lowland soils, whereas the cHCl-Pi fraction was the dominant form in the mineral-II layer. The resistant P content, including NaOH-Pi, HCl-Pi, cHCl-Pi, and cHCl-Po fractions, was higher in the upland than in the lowland. However, the labile P content, NaHCO3-Po, showed the opposite pattern. The content of resistant Pi (NaOH-Pi, HCl-Pi, and cHCl-Pi) increased significantly with depth, but that of labile Pi (resin-Pi and NaHCO3-Pi) and recalcitrant Po (NaHCO3-Po, NaOH-Po, and cHCl-Po) decreased significantly with depth at both locations. 31P-NMR spectroscopy revealed inorganic orthophosphate and monoesters-P as the major forms in this area. The proportions of Pi and Po evaluated by sequential chemical extraction and 31P-NMR spectroscopy were basically consistent. The results indicate that the soils were in weathered conditions. Furthermore, the P distribution and forms in this coastal sand dune landscape significantly differed between the upland and lowland because of the variation in elevation and eolian aggradation effects.

Description: The height of tree stumps following mechanized forest operations can be influenced by machine-, tree-, terrain-, and operator-related characteristics. High stumps may pose different economic and technical disadvantages. Aside from a reduction in product recovery (often associated with sawlog potential), leaving high stumps can complicate future entries if smaller equipment with low ground clearance is used, particularly in the case where new machine operating trails are required. The objective of this exploratory study was to examine if correlations existed between the height of tree stumps following mechanized harvesting and the shape of the above-ground root collar, stump diameter, and distance to the machine operating trail. In total, 202 sample stumps of Norway spruce (Picea abies (L.) Karst.) and the surrounding terrain were scanned with a terrestrial laser scanner. The collected data was processed into a 3D-model and then analyzed. Stump height was compared with different characteristics such as stump diameter at the cut surface, distance to the machine operating trail, number of visible root flares per stump, and the root collar. The number of root flares per stump had a positive influence on stump diameter and height, showing a general trend of increasing diameter and height with the increasing number of root flares. Root angles also had an influence on the stump diameter. The diameter of a stump and the shape of the root collar at the cut surface together had a significant effect on stump height and the model reported explained half of the variation of stump heights. Taken together, these findings suggest that other factors than the ones studied can also contribute in influencing stump height during mechanized harvesting operations. Further investigations, including pre- and post-harvest scans of trees selected for removal, are warranted.

Description: Working time studies, work productivity, and cost assessments of forest logging are of interest to forest managers and planners. These aspects are particularly important in salvage logging, because of difficulties due to irregularly positioned fallen trees in forest areas, and due to particular aspects related to the absence of work planning. In this research, system productivity and the cost of salvage logging are analyzed for two mountain forests managed with close-to nature-silviculture: the Hyrcanian forest, using extraction by a skidder, and the Camaldoli forest, using extraction by tractors. The system productivity of salvage logging by skidders and tractors was calculated as 1.54 and 0.81 m3·h−1, respectively. In contrast to common logging, system productivity was about 6- to 15-fold lower in salvage logging. The effective cost consumptions for the skidder and tractor were calculated as $72.57 and $118.62 USD·m−3, respectively. For both yards, winching time increased due to increasing winching distance and winching load volume. The same result was determined for skidding time in relation to load volume and distance. The possible cost decreases for the skidder and tractor were calculated as 2.6% and 4.3%, respectively. The results revealed that operational costs for extracting wind-fallen trees are higher than for traditional standing-trees extraction for both situations studied. In both cases, the harvesting costs were higher than the timber price by 10% to 30%. Therefore, extraction of wind-fallen trees has no economic justification in these forests.

Description: Research Highlights: Plant cover drives the activity of the microbial decomposer community and affects carbon (C) sequestration in the soil. Despite the relationship between microbial activity and C sequestration in the soil, potential inhibition of soil microbial activity by plant cover has received little attention to date. Background and Objectives: Differences in soil microbial activity between two paired stands on soil at a very early stage of formation and a common story until afforestation, can be traced back to the plant cover. We hypothesized that in a black locust (Robinia pseudoacacia L.) stand the high-quality leaf litter of the tree, and that of the blackberry (Rubus fruticosus L.) understory had an inhibitory effect on soil microbial community resulting in lower mineralization of soil organic matter compared to the paired black pine (Pinus nigra Arn.) stand. Materials and Methods: We estimated potential mineralization rates (MR), microbial (MB), and active fungal biomass (AFB) of newly-shed litter, forest floor, and mineral soil. We tested the effects of litters’ water extracts on soil MR, MB, AFB and its catabolic response profile (CRP). Results: Newly-shed litter of black locust had higher MR than that of blackberry and black pine; MR, MB, and AFB were higher in forest floor and in mineral soil under black pine than under black locust. Water extracts of black locust and blackberry litter had a negative effect on the amount, activity of microorganisms, and CRP. Conclusions: The results demonstrate the potential for black locust and blackberry litter to have a marked inhibitory effect on decomposer microorganisms that, in turn, reduce organic matter mineralization with possible consequences at the ecosystem level, by increasing C sequestration in mineral soil.

Description: Due to its advantages of good heat-resistance, environmental-friendliness, and low cost, bamboo grid packing (BGP) has become a promising new type of cooling packing. It is being increasingly used in Chinese industrial cooling towers to replace cooling packings made of polyvinyl chloride, cement, and glass fiber reinforced plastic. However, mechanical properties and fungal resistance are a concern for all bamboo applications. In this study, the modulus of rupture (MOR), modulus of elasticity (MOE), density, crystallinity, and environment scanning electron microscope (ESEM) properties were compared between fresh BGPs and those that had been in service for nine years in the cooling towers. The results showed that the MOR, MOE, density, crystallinity, and the crystal size of the used BGPs decreased to some extent, but still met the requirements for normal use in a cooling tower. The ESEM observation showed that the used BGPs were not infected by fungi. The decrease in mechanical properties could be caused by the decrease of density, crystallinity, and the decomposition of the chemical components of bamboo, but not by fungal infection.

Description: Wood density profiles reveal a tree’s life strategy and growth. Density profiles are, however, rarely defined in terms of tissue fractions for wood of tropical angiosperm trees. Here, we aim at linking these fractions to corresponding density profiles of tropical trees from the Congo Basin. Cores of 8 tree species were scanned with X-ray Computed Tomography to calculate density profiles. Then, cores were sanded and the outermost 3 cm were used to semi-automatically measure vessel lumen, parenchyma and fibre fractions using the Weka segmentation tool in ImageJ. Fibre wall and lumen widths were measured using a newly developed semi-automated method. An assessment of density variation in function of growth ring boundary detection is done. A mixed regression model estimated the relative contribution of each trait to the density, with a species effect on slope and intercept of the regression. Position-dependent correlations were made between the fractions and the corresponding wood density profile. On average, density profile variation mostly reflects variations in fibre lumen and wall fractions, but these are species- and position-dependent: on some positions, parenchyma and vessels have a more pronounced effect on density. The model linking density to traits explains 92% of the variation, with 65% of the density profile variation attributed to the three measured traits. The remaining 27% is explained by species as a random effect. There is a clear variation between trees and within trees that have implications for interpreting density profiles in angiosperm trees: the exact driving anatomical fraction behind every density value will depend on the position within the core. The underlying function of density will thus vary accordingly.

Description: Wall-to-wall tree-lists information (lists of species and diameter for every tree) at a regional scale is required for managers to assess forest sustainability and design effective forest management strategies. Currently, the k-nearest neighbors (kNN) method and the Weibull diameter distribution function have been widely used for estimating tree lists. However, the kNN method usually relies on a large number of field inventory plots to impute tree lists, whereas the Weibull function relies on strong correlations between stand attributes and diameter distribution across large regions. In this study, we developed a framework to estimate wall-to-wall tree lists over large areas based on a limited number of forest inventory plots. This framework integrates the ability of extrapolating diameter distribution from Weibull and kNN imputation of wall-to-wall forest stand attributes from Moderate Resolution Imaging Spectroradiometer (MODIS). We estimated tree lists using this framework in Chinese boreal forests (Great Xing’an Mountains) and evaluated the accuracy of this framework. The results showed that the passing rate of the Kolmogorov–Smirnov (KS) test for Weibull diameter distribution by species was from 52% to 88.16%, which means that Weibull distribution could describe the diameter distribution by species well. The imputed stand attributes (diameter at breast height (DBH), height, and age) from the kNN method showed comparable accuracy with the previous studies for all species. There was no significant difference in the tree density between the estimated and observed tree-lists. Results suggest that this framework is well-suited to estimating the tree-lists in a large area. Our results were also ecologically realistic, capturing dominant ecological patterns and processes.

Description: Individual tree crown (ITC) segmentation is an approach to isolate individual tree from the background vegetation and delineate precisely the crown boundaries for forest management and inventory purposes. ITC detection and delineation have been commonly generated from canopy height model (CHM) derived from light detection and ranging (LiDAR) data. Existing ITC segmentation methods, however, are limited in their efficiency for characterizing closed canopies, especially in tropical forests, due to the overlapping structure and irregular shape of tree crowns. Furthermore, the potential of 3-dimensional (3D) LiDAR data is not fully realized by existing CHM-based methods. Thus, the aim of this study was to develop an efficient framework for ITC segmentation in tropical forests using LiDAR-derived CHM and 3D point cloud data in order to accurately estimate tree attributes such as the tree height, mean crown width and aboveground biomass (AGB). The proposed framework entails five major steps: (1) automatically identifying dominant tree crowns by implementing semi-variogram statistics and morphological analysis; (2) generating initial tree segments using a watershed algorithm based on mathematical morphology; (3) identifying “problematic” segments based on predetermined set of rules; (4) tuning the problematic segments using a modified distance-based algorithm (DBA); and (5) segmenting and counting the number of individual trees based on the 3D LiDAR point clouds within each of the identified segment. This approach was developed in a way such that the 3D LiDAR points were only examined on problematic segments identified for further evaluations. 209 reference trees with diameter at breast height (DBH) ≥ 10 cm were selected in the field in two study areas in order to validate ITC detection and delineation results of the proposed framework. We computed tree crown metrics (e.g., maximum crown height and mean crown width) to estimate aboveground biomass (AGB) at tree level using previously published allometric equations. Accuracy assessment was performed to calculate percentage of correctly detected trees, omission and commission errors. Our method correctly identified individual tree crowns with detection accuracy exceeding 80 percent at both forest sites. Also, our results showed high agreement (R2 〉 0.64) in terms of AGB estimates using 3D LiDAR metrics and variables measured in the field, for both sites. The findings from our study demonstrate the efficacy of the proposed framework in delineating tree crowns, even in high canopy density areas such as tropical rainforests, where, usually the traditional algorithms are limited in their performances. Moreover, the high tree delineation accuracy in the two study areas emphasizes the potential robustness and transferability of our approach to other densely forested areas across the globe.

Description: Climate change is likely to lead to an increased frequency of droughts and floods, both of which are implicated in large-scale carbon allocation and tree mortality worldwide. Non-structural carbohydrates (NSCs) play an important role in tree survival under stress, but how NSC allocation changes in response to drought or waterlogging is still unclear. We measured soluble sugars (SS) and starch in leaves, twigs, stems and roots of Robinia pseudoacacia L. seedlings that had been subjected to a gradient in soil water availability from extreme drought to waterlogged conditions for a period of 30 days. Starch concentrations decreased and SS concentrations increased in tissues of R. pseudoacacia seedlings, such that the ratio of SS to starch showed a progressive increase under both drought and waterlogging stress. The strength of the response is asymmetric, with the largest increase occurring under extreme drought. While the increase in SS concentration in response to extreme drought is the largest in roots, the increase in the ratio of SS to starch is the largest in leaves. Individual components of SS showed different responses to drought and waterlogging across tissues: glucose concentrations increased significantly with drought in all tissues but showed little response to waterlogging in twigs and stems; sucrose and fructose concentrations showed marked increases in leaves and roots in response to drought but a greater response to drought and waterlogging in stems and twigs. These changes are broadly compatible with the roles of individual SS under conditions of water stress. While it is important to consider the role of NSC in buffering trees against mortality under stress, modelling this behaviour is unlikely to be successful unless it accounts for different responses within organs and the type of stress involved.

Description: Soil enzymes and microbial communities are key factors in forest soil ecosystem functions and are affected by stand age. In this study, we studied soil enzyme activities, composition and diversity of bacterial and fungal communities and relevant physicochemical properties at 0–10 cm depth (D1), 10–20 cm depth (D2) and 20–30 cm depth (D3) soil layers in 3-(3a), 6-(6a), 12-(12a), 18-(18a), 25-(25a), 32-(32a) and 49-year-old (49a) Chinese fir plantations to further reveal the effects of stand age on soil biotic properties. Spectrophotometry and high-throughput sequencing was used to assess the soil enzyme activity and microbial community composition and diversity of Chinese fir plantation of different stand ages, respectively. We found that soil catalase activity increased as the stand age of Chinese fir plantations increased, whereas the activities of urease, sucrase and β-glucosidase in 12a, 18a and 25a were lower than those in 6a, 32a and 49a. Shannon and Chao1 indices of bacterial and fungal communities first decreased gradually from 6a to 18a or 25a and then increased gradually from 25a to 49a. Interestingly, the sucrase and β-glucosidase activities and the Shannon and Chao1 indices in 3a were all lower than 6a. We found that the relative abundance of dominant microbial phyla differed among stand ages and soil depths. The proportion of Acidobacteria first increased and then decreased from low forest age to high forest age, and its relative abundance in 12a, 18a and 25a were higher than 3a, 32a and 49a, but the proportion of Proteobacteria was opposite. The proportion of Ascomycota first decreased and then increased from 6a to 49a, and its relative abundance in 12a, 18a and 25a was lower than 3a, 6a, 32a and 49a. Our results indicate that soil enzyme activities and the richness and diversity of the microbial community are limited in the middle stand age (from 12a to 25a), which is important for developing forest management strategies to mitigate the impacts of degradation of soil biological activities.

Description: The contributions of heterotrophic respiration (RH) to total soil respiration (RS) for the non-growing season, growing season, and annual period are 84.8%, 60.7%, and 63.3%, respectively.Few studies have partitioned RS into its rhizospheric (RR) and heterotrophic components throughout the year in northern forest ecosystems. Our objectives were to quantify the contributions of non-growing season and heterotrophic respiration. We conducted a trenching experiment to quantify RR and RH in a temperate deciduous forest in Northeast China over two years using chamber methods. Temperature sensitivities (Q10) for RS and for RH were both much higher in the non-growing season (November to April) than those in the growing season. The Q10 for RS was higher than Q10 for RH in both seasons, indicating a higher temperature sensitivity of roots versus microorganisms. Mean non-growing season RS, RH, and RR for the two years were 94, 79 and 14 g carbon (C) m−2, respectively, which contributed 10.8%, 14.5%, and 4.5% to the corresponding annual fluxes (869, 547 and 321 g C m−2 year−1, respectively). The contributions of RH to RS for the non-growing season, growing season, and annual period were 84.8%, 60.7%, and 63.3%, respectively. Using the same contribution of non-growing season RS to annual RS, to scale growing season measurements, to the annual scale would introduce significant biases on annual RH (−34 g C m−2 yr−1 or −6%) and RR (16 g C m−2 yr−1 or 5%).We concluded that it was important to take non-growing season measurements in terms of accurately partitioning RS components in northern forests.

Description: Comprehensive evaluation of forest state is the precondition and critical step for forest management. To solve the problem that the radar plot and unit circle only focus on the value of each the evaluation index, this paper proposes a novel method for comprehensively and simultaneously evaluating the functionality and inhomogeneity of forest state based on the modified unit circle method. We evaluated the forest state of the Quercus aliena BL. var. acuteserrata Maxim. ex Wenz. broad-leaved mixed forest in the Xiaolong Mountains Forest Area of Gansu Province and the Pinus koraiensis Sieb. et Zucc. broad-leaved mixed forest in Jilin Province in China. According to the principle of comprehensive, scientific and operability, 10 evaluation indices on forest structure and vitality were selected to construct the evaluation indicator system. Each index was normalized based on the assignment method and ensured to be strictly positive based on reciprocal transformation method. The areas and arc length of the closed graph, formed by connecting every two adjacent indicators, in the radar plot and unit circle were extracted. Based on the isoperimetric theorem (isoperimetric inequality), a comprehensive evaluation model was constructed. Compared with radar chart and unit circle method, each index in the newly proposed unit circle method is represented by an independent sector region, reflecting the contribution of the index to the overall evaluation result. Each index has the same relative importance weight, contributing to the estimation the relative sizes of each aspect of forest state. The unique area and arc length of the closed graph help summarize the overall performance with a global score. The expression effect of improved unit circle has been enhanced, and as an English proverb put it, “A picture is worth a thousand words.” The new proposed method simultaneously evaluates the functionality and inhomogeneity of the forest state and it is a powerful tool for the diagnosis of forest state problems and the decision-making of forest management.

Description: The present study was undertaken to examine the ability of different genomic selection (GS) models to predict growth traits (diameter at breast height, tree height and wood volume), stem straightness and branching quality of Eucalyptus globulus Labill. trees using a genome-wide Single Nucleotide Polymorphism (SNP) chip (60 K), in one of the southernmost progeny trials of the species, close to its southern distribution limit in Chile. The GS methods examined were Ridge Regression-BLUP (RRBLUP), Bayes-A, Bayes-B, Bayesian least absolute shrinkage and selection operator (BLASSO), principal component regression (PCR), supervised PCR and a variant of the RRBLUP method that involves the previous selection of predictor variables (RRBLUP-B). RRBLUP-B and supervised PCR models presented the greatest predictive ability (PA), followed by the PCR method, for most of the traits studied. The highest PA was obtained for the branching quality (~0.7). For the growth traits, the maximum values of PA varied from 0.43 to 0.54, while for stem straightness, the maximum value of PA reached 0.62 (supervised PCR). The study population presented a more extended linkage disequilibrium (LD) than other populations of E. globulus previously studied. The genome-wide LD decayed rapidly within 0.76 Mbp (threshold value of r2 = 0.1). The average LD on all chromosomes was r2 = 0.09. In addition, the 0.15% of total pairs of linked SNPs were in a complete LD (r2 = 1), and the 3% had an r2 value 〉0.5. Genomic prediction, which is based on the reduction in dimensionality and variable selection may be a promising method, considering the early growth of the trees and the low-to-moderate values of heritability found in the traits evaluated. These findings provide new understanding of how develop novel breeding strategies for tree improvement of E. globulus at its southernmost range limit in Chile, which could represent new opportunities for forest planting that can benefit the local economy.

Description: Surface mining for coal (or other mineral resources) is a major driver of land-use change around the world and especially in the Appalachian region of the United States. Intentional and well-informed reclamation of surface-mined land is critical for the restoration of healthy ecosystems on these disturbed sites. In Appalachia, the pre-mining land cover is predominately mixed hardwood forest, with rich species diversity. In recent years, Appalachian mine reforestation has become an issue of concern, prompting the development of the Forestry Reclamation Approach, a series of mine reforestation recommendations. One of these recommendations is to use the best available soil substitute; however, the characteristics of the “best” soil substitute have been an issue. This study was initiated to compare the suitability of several types of mine spoil common in the Appalachian region: brown sandstone (Brown), gray sandstone (Gray), mixed spoils (Mixed), and shale (Shale). Experimental plots were established in 2007 with each spoil type replicated three times. These plots were planted with a mix of native hardwood species. Ten years after plot construction and planting, tree growth and canopy cover were highest in Brown, followed by Shale, Mixed, and Gray. Soil conditions (particularly pH) in Brown and Shale were more favorable for native tree growth than Mixed or Gray, largely explaining these differences in tree growth and canopy cover. However, soil chemistry did not clearly explain differences in tree growth between Brown and Shale. These differences were more likely related to differences in near-surface soil temperature, which is related to soil color and available shade.

Description: Research Highlights: Leaf chemistry is a key driver of litter decomposition; however, studies directly comparing metabolites that are important for tree growth and defence across different woody species are scarce. Background and Objectives: Choosing 14 temperate woody species differing in their growth rates, nutrient demand, shade tolerance, and drought sensitivity, we hypothesized that the species would group according to their metabolite profiles based on their ecological background. Materials and Methods: We analysed total N and C, soluble amino acid, protein, and phenolic levels in green leaves and leaf litter of these species, each in two consecutive years. Results: Metabolite levels varied significantly across species and between the sampling years which differed in temperature and precipitation (i.e., colder/drier vs warmer/ wetter). Conclusions: The 14 woody species could not be grouped according to their green leaf or leaf litter metabolite profiles. In litter leaves, most of the variation was explained by total phenolics and total nitrogen levels, and in green leaves by total phenolics and total soluble amino acid levels. Local climate variation between the two consecutive years for green leaves or leaf litter led to significant differences in metabolite levels, although some of them were species-specific.

Description: The Hungry Bob fuels reduction project was part of a 12-site National Fire and Fire Surrogate (FFS) network of experiments conducted across the United States from the late 1990s through the early 2000s to determine the regional differences in applying alternative fuel-reduction treatments to forests. The Hungry Bob project focused on restoration treatments applied in low elevation, dry second-growth ponderosa pine (Pinus ponderosa subsp. ponderosa (Douglas ex C. Lawson) and Douglas-fir (Pseudotsuga menziesii subsp. glauca (Beissn.) Franco forests of northeastern Oregon. Treatments included a single entry thin from below in 1998, a late season burn in 2000, a thin (1999) followed by burning (2000), and a no-treatment control. This paper represents results 20 years after treatments and focuses on the treatment effects upon tree diameter growth, crown health, and ladder fuel conditions within the dry eastside stands. The Thin + Burn units produced the best diameter growth in ponderosa pine trees, whereas the Thin units had the best growth for Douglas-fir. The Burn treatment did not improve diameter growth over the Controls. The Thin + Burn treatments also produced trees with the highest tree crown ratios. The Burn unit trees had lower crown ratios compared to the Control trees. The crown reduction (reduction in tree crown ratio since 2004) was largest in the Burn-only units and smallest in the Thin + Burn units. Finally, the heights to the lower tree crowns were highest in the Thin + Burn trees and lowest in the Burn unit trees. Based upon the 20-year responses, the Thin + Burn treatments produced the best conditions for stand growth, while limiting fire stress upon residual tree crowns. It also proved most effective at reducing ladder fuels as represented by higher tree crown heights.

Description: Liriodendron is a Tertiary period relic tree genus with a typical East Asian and North American disjunction distribution pattern. As an angiosperm base group of trees, Liriodendron provides a valuable resource for the study of evolution processes. Here, we reconstruct the phylogeny and population genetic structure of Liriodendron based on the restriction site-associated DNA sequencing (RAD-Seq) of a wide collection of individuals from 16 populations. Our results reveal a clear phylogenetic break between L. chinense and L. tulipifera and obvious genetic divergence between the eastern and western populations of L. chinense, which are consistent with the patterns of geographical distributions. The phylogeographic history and long-term geographical isolation of the genus may be responsible for this pattern. Furthermore, a closer relationship was found between L. tulipifera and the eastern populations of L. chinense, indicating the ancient phylogeny of L. chinense in this area. The results of this study will aid in the development of scientific strategies for the conservation and utilization of the Liriodendron germplasm.

Description: The main purpose of this investigation was to describe the spatial arrangement of shoot tissues, as seen in transverse section, and allometric relationships in two contrasting species of Polygonatum i.e., Polygonatum odoratum which commonly grows in mixed pine-oak forest with shoots rectangular in shape, and Polygonatum multiflorum found in oak-hornbeam forest with cylindrical shoots. The mass and length of the aerial shoots of each individual plant were measured. The shoot regions of each plant were then categorized as basal (b), central (c) or apical (a). Transverse sections of these shoot regions were subsequently cut, and the following parameters were measured: (1) Diameter of shoots, (2) thickness of the outer and inner zones of parenchyma and (3) thickness of the sclerenchyma zone. Additional allometric relationships between the various measurements were computed and determined as Pearson’s correlation coefficients (r). Both species of Polygonatum differed significantly with respect to the length, diameter and thickness of the outer zone of parenchyma. Shoots of P. multiflorum were taller but narrower than those of P. odoratum, which had a significantly wider zone of outer parenchyma. Allometric relationships were stronger for P. multiflorum, and for both species, they were generally stronger in the basal part of the shoot. We conclude that in P. multiflorum, the strong correlation between the diameter and length of the shoot seems to be important to the growth in shaded environments.

Description: Camellia oleifera Abel., is an important woody plant, and its fruit contains high-quality edible oil. Production of C. oleifera has significantly expanded over the last 20 years in China. Due to the lack of appropriate information on nutrient management, its production has encountered low yield and low oil quality problems. As nitrogen (N) is an essential nutrient and the most abundant in C. oleifera tissues, the present study investigated effects of different ratios of nitrate (NO3−) and ammonium (NH4+) on the growth of a cultivar Xianglin 27 at the seedling stage. Uniform seedlings were grown in a soil-based substrate in containers and fertigated with solutions composed of six ratios of NO3− and NH4+, respectively for five months. Results showed that C. oleifera prefers both NO3− and NH4+ at a ratio of 1:1. Seedlings receiving this solution had the highest total N in leaves and total dry weight; elevated chrolophyll, soluble saccharide and protein contents as well as higher activities of peroxidase (POD), superoxide dismutase (SOD), nitrate reductase (NR), glutamine synthetase (GS), and glutamate synthase (GOGAT). Our study shows for the first time that N supply for producing C. oleifera should be an equal ratio of NO3− and NH4+.

Description: The supply of nutrients in balanced proportions leads to greater crop yields and represents an alternative practice for the management of plant diseases. Accordingly, we investigated the effect of the doses of and the nutritional balance between calcium (Ca) and potassium (K) on the severity of leaf spot and defoliation caused by the fungus Calonectria pteridis. Moreover, the effect of the treatments on the growth of interspecific hybrid eucalyptus clone seedlings (Eucalyptus grandis Hill ex Maiden × E. urophylla S.T. Blake), which are highly susceptible to the disease, was evaluated. The 25 treatments comprised combinations of one of five doses of Ca (1.2, 3.0, 6.0, 9.0 and 12.0 mmol L−1) with one of five doses of K (0.8, 2.0, 4.0, 8.0 and 12.0 mmol L−1) and five replicates of each treatment were included in the study. The supply of high concentrations of K favoured C. pteridis infection and resulted in high disease severity, although defoliation was not observed. However, the supply of both nutrients in excess (12.0 mmol L−1 Ca × 9.0 mmol L−1 K) resulted in a higher disease severity and an increased defoliation percentage (82 and 64%, respectively). Defoliation not associated with Calonectria leaf blight disease was observed with the imbalanced treatments, that is, the treatments combining a low concentration of one nutrient and an excess concentration of the other nutrient. The supply of K at a level near the standard dose (6 mmol L−1) and of Ca at a dose above 4 mmol L−1 (standard dose) ensured high mean values for the morphological variables root and shoot biomass, plant height and chlorophyll a and b contents. These treatments also resulted in low disease severity and defoliation percentages, indicating that a balanced supply of Ca and K ensures reductions in disease severity and defoliation and contributes to higher growth.

Description: Natural and human-induced disturbances influence the biodiversity and functionality of forest ecosystems. Regular, repeated assessments of canopy intactness are essential to map site-specific forest disturbance and recovery patterns, an essential requirement for forest monitoring and management. However, accessibility to images required for this practice, uncertainty around the levels of accuracy achieved with images of different resolution, and the affordability of the practice challenges its application in many developing regions. This study aimed to compare the accuracy of forest gap detection (in subtropical forests) achieved with lower-resolution (SPOT7 5 m) and higher-resolution (SPOT7 1.5 m) pan-sharpened imagery. Additionally, the Normalised Difference Vegetation Index (NDVI) and Synthetic Aperture Radar (SAR) were compared in terms of their ability to increase the accuracy of this detection when used in conjunction with both high and low resolution imagery. Results indicate that the SPOT7 1.5 m imagery produced an overall accuracy of 77.78% and a ϰ coefficient of 0.66 compared with the 69.44% accuracy and the 0.59 ϰ coefficient achieved with the SPOT7 5 m imagery. Computing image texture analysis within the Random Forest classifier (RF) framework increased classification accuracies to 75.00% for the SPOT 5 m and 86.11% for the SPOT7 1.5 m imagery, validating the usefulness of texture analysis. Variable importance was used to identify wavebands and texture-derived variables that were the most effective in discriminating canopy gaps from intact canopy. In this regard, near infrared, NDVI, SAR, contrast, mean, entropy and second moment were the most important. Collectively the results indicate that the approach adopted in this study, i.e., the use of SPOT7 1.5 m imagery in conjunction with image texture analysis and variable importance, can be used to accurately discriminate between canopy gaps and intact canopy, making it a cost-effective spatial approach for monitoring and managing natural forests.

Description: The use of heat-treated timber for building with wood is of increasing interest. Heat treatment improves the durability and dimensional stability of wood; however, it needs to be optimized to keep wood’s mechanical properties in view of the possible structural use of timber. Therefore, dry vacuum heat treatment varying the maximum temperature between 170 °C and 230 °C was used on fir (Abies alba Mill.) structural timber, visually top graded according to EN 338, to analyze its final weight loss, hygroscopicity, CIELAB color, and dynamic elastomechanical properties. It turned out that weight loss and total color difference of wood positively correlates with the increasing intensity of the heat treatment. The maximum 40% reduction of the hygroscopicity of wood was already reached at 210 °C treatment temperature. The moduli of elasticity in longitudinal and radial direction of wood, determined by ultrasound velocity, increased initially up to the treatment temperature of 210 °C, and decreased at higher treatment temperature. Equally, the Euler-Bernoulli modulus of elasticity from free-free flexural vibration of boards in all five vibration modes increased with the rising treatment temperature up to 190 °C, and decreased under more intensive treatment conditions. The Euler-Bernoulli model was found to be valid only in the 1st vibration mode of heat-treated structural timber due to the unsteady decrease in the evaluated moduli of elasticity related to the increasing mode number.

Description: Wood supply predictions from forest inventories involve two steps. First, it is predicted whether harvests occur on a plot in a given time period. Second, for plots on which harvests are predicted to occur, the harvested volume is predicted. This research addresses this second step. For forests with more than one species and/or forests with trees of varying dimensions, overall harvested volume predictions are not satisfactory and more detailed predictions are required. The study focuses on southwest Germany where diverse forest types are found. Predictions are conducted for plots on which harvests occurred in the 2002–2012 period. For each plot, harvest probabilities of sample trees are predicted and used to derive the harvested volume (m³ over bark in 10 years) per hectare. Random forests (RFs) have become popular prediction models as they define the interactions and relationships of variables in an automatized way. However, their suitability for predicting harvest probabilities for inventory sample trees is questionable and has not yet been examined. Generalized linear mixed models (GLMMs) are suitable in this context as they can account for the nested structure of tree-level data sets (trees nested in plots). It is unclear if RFs can cope with this data structure. This research aims to clarify this question by comparing two RFs—an RF based on conditional inference trees (CTree-RF), and an RF based on classification and regression trees (CART-RF)—with a GLMM. For this purpose, the models were fitted on training data and evaluated on an independent test set. Both RFs achieved better prediction results than the GLMM. Regarding plot-level harvested volumes per ha, they achieved higher variances explained (VEs) and significantly (p 〈 0.05) lower mean absolute residuals when compared to the GLMM. VEs were 0.38 (CTree-RF), 0.37 (CART-RF), and 0.31 (GLMM). Root means squared errors were 138.3, 139.9 and 145.5, respectively. The research demonstrates the suitability and advantages of RFs for predicting harvest decisions on the level of inventory sample trees. RFs can become important components within the generation of business-as-usual wood supply scenarios worldwide as they are able to learn and predict harvest decisions from NFIs in an automatized and self-adapting way. The applied approach is not restricted to specific forests or harvest regimes and delivers detailed species and dimension information for the harvested volumes.

Description: Research Highlights: The biology of mountain pine beetle (MPB), Dendroctonus ponderosae Hopkins, in Colorado’s lodgepole pine forests exhibits similarities and differences to other parts of its range. Brood emergence was not influenced by stand density nor related to tree diameter. The probability of individual tree attack is influenced by stocking and tree size. Findings have implications for understanding MPB as a disturbance agent and for developing management strategies. Background and Objectives: MPB causes extensive tree mortality of lodgepole pine, Pinus contorta Douglas ex Loudon, across the western US and Canada and is probably the most studied bark beetle in North America. However, most of the current knowledge on the biology and ecology of MPB in lodgepole pine comes from the Intermountain Region of the US and western Canada. Little information is available from Colorado. This is the first study addressing effects of stand stocking levels on the biology of MPB and quantifying phloem consumption. In addition, although data are available on the conditions that foster stand infestation, this is the first study estimating the probability of individual tree attack among stands of known different stocking. Materials and Methods: Studies were conducted in managed lodgepole pine stands in Colorado. Unbaited traps were used to monitor MPB flight across stands of different densities. Cages were used to monitor emergence and bark samples to determine attack densities, and phloem consumption in trees growing under different stocking. Beetle collections were used to determine emergence across the growing season. Tree mortality data from plots of different densities were used to examine the probability of individual tree infestation. Results: More beetles were caught flying through higher density stands. More attacks were observed in lower stocking stands but there were no differences in the number of insects emerging nor phloem consumption. There was no relationship between tree size and beetle emergence. Peak flight occurred in early to mid-August and only one peak of beetle emergence occurred. The probability of tree attack was influenced by stand stocking and tree diameter. Conclusions: In general, aspects of the biology of MPB in Colorado exhibit similarities and differences with other regions. The data suggest the need to more closely examine how MPB functions in stands of different stocking and how the distribution of tree sizes influence the probability of infestation and extent of mortality in stands. Biological characteristics of MPB in Colorado need further examination, particularly as climate change continues to manifest. Baseline information will be critical to refine management approaches, and extend the understanding of how MPB contributes to shape forest composition and structure in Colorado.

Description: The moisture content (MC) control is vital in the wood drying process. The study was based on BP (Back Propagation) neural network algorithm to predict the change of wood MC during the drying process of a high frequency vacuum. The data of real-time online measurement were used to construct the model, the drying time, position of measuring point, and internal temperature and pressure of wood as inputs of BP neural network model. The model structure was 4-6-1 and the decision coefficient R2 and Mean squared error (Mse) of the training sample were 0.974 and 0.07355, respectively, indicating that the neural network model had superb generalization ability. Compared with the experimental measurements, the predicted values conformed to the variation law and size of experimental values, and the error was about 2% and the MC prediction error of measurement points along thickness direction was within 2%. Hence, the BP neural network model could successfully simulate and predict the change of wood MC during the high frequency drying process.

Description: Warmer and drier climates over Amazonia have been predicted for the next century with expected changes in regional water and carbon cycles. We examined the impact of interannual and seasonal variations in climate conditions on ecosystem-level evapotranspiration (ET) and water use efficiency (WUE) to determine key climatic drivers and anticipate the response of these ecosystems to climate change. We used daily climate and eddyflux data recorded at the Guyaflux site in French Guiana from 2004 to 2014. ET and WUE exhibited weak interannual variability. The main climatic driver of ET and WUE was global radiation (Rg), but relative extractable water (REW) and soil temperature (Ts) did also contribute. At the seasonal scale, ET and WUE showed a modal pattern driven by Rg, with maximum values for ET in July and August and for WUE at the beginning of the year. By removing radiation effects during water depleted periods, we showed that soil water stress strongly reduced ET. In contrast, drought conditions enhanced radiation-normalized WUE in almost all the years, suggesting that the lack of soil water had a more severe effect on ecosystem evapotranspiration than on photosynthesis. Our results are of major concern for tropical ecosystem modeling because they suggest that under future climate conditions, tropical forest ecosystems will be able to simultaneously adjust CO2 and H2O fluxes. Yet, for tropical forests under future conditions, the direction of change in WUE at the ecosystem scale is hard to predict, since the impact of radiation on WUE is counterbalanced by adjustments to soil water limitations. Developing mechanistic models that fully integrate the processes associated with CO2 and H2O flux control should help researchers understand and simulate future functional adjustments in these ecosystems.

Description: The black timber bark beetle Xylosandrus germanus (Blandford) is an invasive ambrosia beetle that originates from Southeast Asia and has become successfully established within Europe and North America. Herein, we provide a review of the spread and distribution of this tree and timber pest species across Europe, before and after 2000, along with a review of its habitat preferences. Since the spread of X. germanus across Europe has accelerated rapidly post-2000, emphasis is placed on this period. X. germanus was first recorded in Germany in 1951 and since then in 21 other European countries along with Russia. Ethanol-baited traps were deployed in oak, beech, and spruce forest ecosystems in the Western Carpathians, Central Europe, Slovakia, to characterize the distribution and habitat preferences of this non-native ambrosia beetle. Captures of X. germanus within Slovakia have been rising rapidly since its first record in 2010, and now this species dominates captures of ambrosia beetles. X. germanus has spread throughout Slovakia from south-southwest to north-northeast over a period of 5–10 years, and has also spread vertically into higher altitudes within the country. While living but weakened trees in Europe and North America are attacked by X. germanus, the greatest negative impact within Slovakia is attacks on recently felled logs of oak, beech and spruce trees, which provide high quality timber/lumber. We suggest that the recent rapid spread of X. germanus in Central Europe is being facilitated by environmental changes, specifically global warming, and the increasing frequency of timber trade. Recommendations for the management of X. germanus in forest ecosystems are proposed and discussed, including early detection, monitoring, sanitary measures, etc.

Description: This study presents two stand-density indices (SDIs) based on exponential density decline as a function of quadratic mean diameter for all species combined in mixed-species forests with 22 species mix grouped in four species groups. The exponential-based density–diameter relationship, as well the density index corresponding to the slope or instantaneous mortality rate parameters, was compared with those based on power-law density–diameter relationship. A dataset of 202 fully stocked circular plots at maximum density was used for fitting the models, and a dataset of 122 circular plots was used for validation stand density index for all species combined of mixed-species stands. The dataset for validation was independent of dataset for model development. The first stand-density index showed a density management graphic (DMG) with a variable intercept and common instantaneous mortality rate, and the second index showed a DMG with common intercept and variable mortality rate. Additionally, the value of the initial density of the fitted line was more realistic than those generated by the potential model for all species combined. Moreover, the density management diagrams showed a curvilinear trend based on the maximum stand density index in graphical log–log scale. The DMGs could be interpreted as forest scenarios based on variable initial density and common management objectives or the same density and different management objectives for forest-rotation periods involving all species combined in mixed-species stands. The fitting of exponential and potential equations for species or species groups showed that the density–size relationships in mixed-species forests should be modeled for all species combined because the disaggregation of mixture species represented a weak tendency for each species or species group and the resultant fitted equations were unrealistic.

Description: This study investigated the control of Fusarium root rot and development of coastal pine (Pinus thunbergii) seedlings in a container nursery by using Bacillus licheniformis MH48. High-quality seedlings without infectious diseases cause vigorous growth. Fusarium root rot caused by Fusarium oxysporum is responsible for serious damage to coastal pine seedlings in nurseries. B. licheniformis MH48 produced enzymes that degraded the fungal cell walls, such as chitinase and β-1,3-glucanase. These lytic enzymes exhibited destructive activity toward F. oxysporum hyphae, which were found to play key roles in the suppression of root rot. In addition, B. licheniformis MH48 increased the nitrogen and phosphorus in soils via fixed atmospheric nitrogen and solubilized inorganic phosphate. B. licheniformis MH48 produced the phytohormone auxin, which stimulated seedling root development, resulting in increased nutrient uptake in seedlings. Both the bacterial inoculation and the chemical fertilizer treatments significantly increased seedling growth and biomass, and the bacterial inoculation had a greater effect on seedling development. Based on the results from this study, B. licheniformis MH48 showed potential as a biological agent against Fusarium root rot and as a promoter of growth and development of Pinus thunbergii seedlings.

Description: Trochodendron aralioides Siebold & Zuccarini (Trochodendraceae) is a famous relic tree species. Understanding the comprehensive spatial distribution and likely impacts of climate change on T. aralioides in its main habitat—Taiwan—is of great importance. We collected occurrence data and bioclimatic data to predict the current and future (year 2050) distribution by ensemble distribution modeling on the BIOMOD2 platform. Visualization of occurrence point data revealed that the main population of T. aralioides was concentrated at medium altitudes and extended to both ends of Taiwan, being especially rich in the northern low mountains. A similar distribution pattern of occurrence probability was shown by ensemble prediction of the true skill statistic 〉0.8 models. Comparing the current and future distribution of T. aralioides, the overlay analysis with profile display demonstrated spatial turnover that revealed a discrepancy between different latitudes and altitudes. In the future climate, T. aralioides at the middle altitudes of central Taiwan could migrate upward, but its population in northern Taiwan could lose most of its habitat. Consequently, T. aralioides in the low mountains of northern Taiwan could be particularly in need of further conservation research, which is urgently required to mitigate climate change impacts.

Description: The significance of street-side greenery monitoring is increasing for precise urban planning and environmental management, especially in rapid sprawling urban cities, while there have been few studies focusing on urban greenery estimation using new profile image system. In this study, Baidu Street View (BSV) images, which were taken by Baidu vehicles and had view angles similar to those of pedestrians on the street, were selected for calculating the magnitude of street profile greenery. From 278 randomly selected street sample sites in Tai’an city of China, 3336 images were acquired via the Baidu Application Programming Interface (API). A Baidu Green View Index (BGVI) was proposed to quantitatively describe the street-side profile greenery. The results demonstrated that green vegetation can be distinguished efficiently from BSV images. The BGVI varied in the different portions of the study area, and it can be used to grade street system by considering pedestrians’ visualized greenery. Though BGVI had a significant correlation with the overlooking green canopy coverage, in some street sample sites it can delineate different scenarios. BGVI can be regarded as complementary information to urban planning and management.

Description: As a brassinosteroid (BR), 24-epibrassinolide (24-epiBL) has been widely used to enhance the resistance of plants to multiple stresses, including salinity. Black locust (Robinia pseudoacacia L.) is a common species in degraded soils. In the current study, plants were pretreated with three levels of 24-epiBL (0.21, 0.62, or 1.04 µM) by either soaking seeds during the germination phase (Sew), foliar spraying (Spw), or root dipping (Diw) at the age of 6 months. The plants were exposed to salt stress (100 and 200 mM NaCl) via automatic drip-feeding (water content ~40%) for 45 days after each treatment. Increased salinity resulted in a decrease in net photosynthesis rate (Pn), stomatal conductance (Gs), intercellular:ambient CO2 concentration ratio (Ci/Ca), water-use efficiency (WUEi), and maximum quantum yield of photosystem II (PSII) (Fv/Fm). Non-photochemical quenching (NPQ) and thermal dissipation (Hd) were elevated under stress, which accompanied the reduction in the membrane steady index (MSI), water content (RWC), and pigment concentration (Chl a, Chl b, and Chl). Indicators of oxidative stress (i.e., malondialdehyde (MDA) and antioxidant enzymes (peroxidase (POD) and superoxide dismutase (SOD)) in leaves and Na+ content in chloroplasts increased accompanied by a reduction in chloroplastid K+ and Ca2+. At 200 mM NaCl, the chloroplast and thylakoid ultrastructures were severely disrupted. Exogenous 24-epiBL improved MSI, RWC, K+, and Ca2+ content, reduced Na+ levels, maintained chloroplast and thylakoid membrane structures, and enhanced the antioxidant ability in leaves. 24-epiBL also substantially alleviated stress-induced limitations of photosynthetic ability, reflected by elevated chlorophyll fluorescence, pigment levels, and Pn. The positive effects of alleviating salt stress in R. pseudoacacia seedlings in terms of treatment application was Diw 〉 Sew 〉 Spw, and the most positive impacts were seen with 1.04 µM 24-epiBL. These results provide diverse choice for 24-epiBL usage to defend against NaCl stress of a plant.

Description: With the significant progress of urbanization, cities and towns are suffering from air pollution, heat island effects, and other environmental problems. Urban vegetation, especially trees, plays a significant role in solving these ecological problems. To maximize services provided by vegetation, urban tree species should be properly selected and optimally arranged. Therefore, accurate classification of tree species in urban environments has become a major issue. In this paper, we reviewed the potential of light detection and ranging (LiDAR) data to improve the accuracy of urban tree species classification. In detail, we reviewed the studies using LiDAR data in urban tree species mapping, especially studies where LiDAR data was fused with optical imagery, through classification accuracy comparison, general workflow extraction, and discussion and summarizing of the specific contribution of LiDAR. It is concluded that combining LiDAR data in urban tree species identification could achieve better classification accuracy than using either dataset individually, and that such improvements are mainly due to finer segmentation, shadowing effect reduction, and refinement of classification rules based on LiDAR. Furthermore, some suggestions are given to improve the classification accuracy on a finer and larger species level, while also aiming to maintain classification costs.

Description: The assessment of mature urban tree vitality using physiological measurements is still in its infancy. Chlorophyll fluorescence is a method for assessing tree vitality that has potential for use in urban environments, particularly on trunk bark, which is easy to access from the ground. Here we describe how we compared bark and leaf fluorescence in a variety of street and park trees (Ficus macrophylla Pers., Platanus × acerifolia (Aiton) Willd., and Ulmus parvifolia Jacq.) with pre-dawn water potential as a way of determining the cause of potential physiological stress in the summer of 2012. Statistical relationships were observed between bark chlorophyll fluorescence and pre-dawn water potential in Ficus macrophylla and Platanus × acerifolia, but were not as consistent in Ulmus parvifolia. In addition, bark and leaf chlorophyll fluorescence were compared with an urban visual vitality index both in autumn 2011 and summer 2012. In this case statistical relationships between bark chlorophyll fluorescence values and urban tree visual vitality were almost non-existent in the Ficus macrophylla and Platanus × acerifolia trees, however, statistical relationships were significant between bark chlorophyll fluorescence and the urban tree vitality index in Ulmus parvifolia. Bark chlorophyll fluorescence may become a useful tool for measuring physiological stress in trees, but further work needs to be undertaken to clarify and better understand the varying responses of different tree species.

Description: Biomass is a key biophysical parameter used to estimate carbon storage and forest productivity. Spatially-explicit estimation of biomass provides invaluable information for carbon stock calculation and scientific forest management. Nevertheless, there still exists large uncertainty concerning the relationship between biomass and influential factors. In this study, aboveground biomass (AGB) was estimated using the random forest algorithm based on remote sensing imagery (Landsat) and field data for three regions with different topographic conditions in Zhejiang Province, China. AGB distribution and change combined with stratified terrain classifications were analyzed to investigate the relations between AGB and topography conditions. The results indicated that AGB in three regions increased from 2010 to 2015 and the magnitude of growth varied with elevation, slope, and aspect. In the basin region, slope had a greater influence on AGB, and we attributed this negative AGB-elevation relationship to ecological forest construction. In the mountain area, terrain features, especially elevation, showed significant relations with AGB. Moreover, AGB and its growth showed positive relations with elevation and slope. In the island region, slope also played a relatively more important role in explaining the relationship. These results demonstrate that AGB varies with terrain conditions and its change is a consequence of interactions between the natural environment and anthropogenic behavior, implying that biomass retrieval based on Landsat imagery could provide considerable important information related to regional heterogeneity investigations.

Description: A regional decline in the Korean fir (Abies koreana) has been observed since the 1980s in the subalpine region. To explain this decline, it is important to investigate the degree to which environmental factors have contributed to plant distributions on diverse spatial scales. We applied a hierarchical regression model to determine quantitatively the relationship between the abundance of Korean fir (seedlings) and diverse environmental factors across two different ecological scales. We measured Korean fir density and the occurrence of its seedlings in 102 (84) plots nested at five sites and collected a range of environmental factors at the same plots. Our model included hierarchical explanatory variables at both site-level (weather conditions) and plot-level (micro-topographic factors, soil properties, and competing species). The occurrence of Korean fir seedlings was positively associated with moss cover and rock cover but negatively related to dwarf bamboo cover. At the site level, winter precipitation was significantly and positively related to the occurrence of seedlings. A hierarchical Poisson regression model revealed that Korean fir density was negatively associated with slope aspect, topographic position index, Quercus mongolica cover, and mean summer temperature. Our results suggest that rising temperature, drought, and competition with other species are factors that impede the survival of the Korean fir. We can predict that the population of Korean fir will continue to decline in the subalpine, and only a few Korean fir will survive on northern slopes or valleys due to climate change.

Description: Mexico is home to the highest species diversity of pines: 46 species out of 113 reported around the world. Within the great diversity of pines in Mexico, Pinus culminicola Andresen et Beaman, P. jaliscana Perez de la Rosa, P. maximartinenzii Rzed., P. nelsonii Shaw, P. pinceana Gordon, and P. rzedowskii Madrigal et M. Caball. are six catalogued as threatened or endangered due to their restricted distribution and low population density. Therefore, they are of special interest for forest conservation purposes. In this paper, we aim to provide up-to-date information on the spatial distribution of these six pine species according to different historical registers coming from different herbaria distributed around the country by using spatial modeling. Therefore, we recovered historical observations of the natural distribution of each species and modelled suitable areas of distribution according to environmental requirements. Finally, we evaluated the distributions by contrasting changes of vegetation in the period 1991–2016. The results highlight areas of distribution for each pine species in the northeast, west, and central parts of Mexico. The results of this study are intended to be the basis of in situ and ex situ conservation strategies for the endangered Mexican pines.

Description: Zanthoxylum bungeanum Maxim. is an economically important tree species that is resistant to drought and infertility, and has potential medicinal and edible value. However, comprehensive genomic data are not yet available for this species, limiting its potential utility for medicinal use, breeding programs, and cultivation. Transcriptome sequencing provides an effective approach to remedying this shortcoming. Herein, single-molecule long-read sequencing and next-generation sequencing approaches were used in parallel to obtain transcript isoform structure and gene functional information in Z. bungeanum. In total, 282,101 reads of inserts (ROIs) were identified, including 134,074 full-length non-chimeric reads, among which 65,711 open reading frames (ORFs), 50,135 simple sequence repeats (SSRs), and 1492 long non-coding RNAs (lncRNAs) were detected. Functional annotation revealed metabolic pathways related to aroma components and color characteristics in Z. bungeanum. Unexpectedly, 30 transcripts were annotated as genes involved in regulating the pathogenesis of breast and colorectal cancers. This work provides a comprehensive transcriptome resource for Z. bungeanum, and lays a foundation for the further investigation and utilization of Zanthoxylum resources.

Description: We analysed 10 years (2008–2017) of continuous eddy covariance (EC) CO2 flux measurements of net ecosystem exchange (NEE) in a young pedunculate oak forest in Croatia. Measured NEE was gap-filled and partitioned into gross primary productivity (GPP) and ecosystem reparation (RECO) using the online tool by Max Planck Institute for Biogeochemistry in Jena, Germany. Annual NEE, GPP, and RECO were correlated with main environmental drivers. Net primary productivity was estimated from EC (NPPEC), as a sum of −NEE and Rh obtained using a constant Rh:RECO ratio, and from independent periodic biometric measurements (NPPBM). For comparing the NPP at the seasonal level, we propose a simple model that aimed at accounting for late-summer and autumn carbon storage in the non-structural carbohydrate pool. Over the study period, Jastrebarsko forest acted as a carbon sink, with an average (±std. dev.) annual NEE of −319 (±94) gC m−2 year−1, GPP of 1594 (±109) gC m−2 year−1, and RECO of 1275 (±94) gC m−2 year−1. Annual NEE showed high inter-annual variability and poor correlation with annual average global radiation, air temperature, and total precipitation, but significant (R2 = 0.501, p = 0.02) correlation with the change in soil water content between May and September. Comparison of annual NPPEC and NPPBM showed a good overall agreement (R2 = 0.463, p = 0.03), although in all years NPPBM was lower than NPPEC, with averages of 680 (±88) gC m−2 year−1 and 819 (±89) gC m−2 year−1, respectively. Lower values of NPPBM indicate that fine roots and grasses contributions to NPP, which were not measured in the study period, could have an important contribution to the overall ecosystem NPP. At a seasonal level, two NPP estimates showed differences in their dynamic, but the application of the proposed model greatly improved the agreement in the second part of the growing season. Further research is needed on the respiration partitioning and mechanisms of carbon allocation.

Description: Bamboo has invaded native forests worldwide, and its aggressive spread by rhizomes facilitates patch expansion and the eventual replacement of adjacent forests. However, fine-scale studies of the spatial pattern and competitive relationships of bamboo in native forests are still lacking. We obtained data from nine plots in a native south subtropical rainforest in Guizhou Province, northwest China. Pair-correlation functions indicated that competition caused by bamboo expansion has not led to large-scale regular spatial distributions in bamboo forest and negative density-related dependence mechanisms regulating the spatial pattern of the native forest community. Marked correlation functions indicated small bamboo in clusters form colony patches that grow around the larger mature trees, resulting in patch expansion in the native forest community. Mark variogram functions identified significant positive spatial autocorrelation of moso bamboo caused by interactions with similar-sized trees within colony patches. This study showed that moso bamboo has colonized and expanded within the native forest community. Compared to the native forest species, the strategy of patch expansion and equal tree sizes in colony patches of moso bamboo could prevent regular distribution trend and size-asymmetric competition between nearby bamboo for the asymmetric and limited sources (i.e., light) in the forest, enhancing the persistence of moso bamboo in the native forest in our study stand located in a south subtropical rainforest in a river valley.

Description: We developed two tree-ring chronologies of teak (Tectona grandis L.f.) from Mae Tuen (462-year, 1555–2016) and Umphang (165-year, 1852–2016) in Tak province, northwestern Thailand. The chronologies were based on 67 and 71 living teak trees, respectively. We used crossdating methods to check and verify the tree-ring width data and tree-ring chronology construction using the ARSTAN program. In this study, the two teak tree-ring chronologies from two different growth areas could not be crossdated. The relationship among these chronologies is, thus, relatively low (r = 0.33, n = 165, p 〈 0.01). This result shows that the growth of tree-ring structure from two sites can be affected by a variety of non-climatic patterns due to site variation, such as topography, nutrient, light, and internal factors. However, these chronologies have a significant positive correlation with rainfall, during the pre-monsoon season (April to May). As demonstrated by the spatial correlation patterns, these chronologies represent April to May rainfall, which was a limiting factor of teak growth from northwestern Thailand. While the difference in surface temperatures of the Indian Ocean Dipole (IOD) might not be affected by rainfall, its unstable relationship with the El Niño-Southern Oscillation (ENSO) was noted to have occurred.

Description: Research Highlights: Some organisms such as plants and fungi release certain secondary metabolites, generally called allelochemicals, which can influence the organisms around them. Some of the secondary metabolites released by mushrooms may have certain effects on the growth and development of neighboring plants. Background Objectives: The purpose of the present study was to investigate the allelopathic potential of mushrooms in a forest ecosystem. To this end, 289 Japanese mushroom species were collected from the wild and tested using a modified sandwich method, which is a quick and effective bioassay technique. Materials and Methods: The collected specimens were prepared for bioassay as dried samples, and 10 mg/well (10 cm2) was added to a 6-well multidish according to the mycelia biomass, which was estimated at 700−900 kg ha−1 year−1 (7–9 mg 10 cm−2) in coniferous forests. Results: Of the screened mushroom species, 74% inhibited more than 50% of the radicle elongation in lettuce (Lactuca sativa var. Great Lakes 366) seedlings, while the average of all species was 41.1%. This result suggests that wild mushrooms have a significant regulatory effect on lettuce growth. According to our standard deviation variance analysis, 54 out of 289 species showed significant allelopathic activity. Among these species, Xeromphalina tenuipes, Cortinarius violaceus, and Clavaria miyabeana exhibited the strongest growth inhibitory activity, with radicle elongation of 5.1%, 4.3%, and 7.6% of the control, respectively. In contrast, Ischnoderma resinosum stimulated the length of radicle and hypocotyl growth by 30.6% and 42.0%, respectively. These results suggest that these species may play important roles in ecosystems. In addition, the wide range of allelopathic activities observed in mushrooms indicates that various amounts of diverse secondary metabolites from these species are involved in mushroom allelopathy. Conclusions: Our study reveals the importance of evaluating mushroom allelopathy to understand the wider ecological structures within complex ecosystems.

Description: Leaf stoichiometry (nitrogen (N), phosphorus (P) and N:P ratio) is not only important for studying nutrient composition in forests, but also reflects plant biochemical adaptation to geographic and climate conditions. However, patterns of leaf stoichiometry and controlling factors are still unclear for most species. In this study, we determined leaf N and P stoichiometry and their relationship with soil properties, geographic and climate variables for Cyclocarya paliurus based on a nation-wide dataset from 30 natural populations in China. The mean values of N and P concentrations and N:P ratios were 9.57 mg g−1, 0.91 mg g−1 and 10.51, respectively, indicating that both leaf N and P concentrations in C. paliurus forests were lower than those of China and the global flora, and almost all populations were limited in N concentration. We found significant differences in leaf N and P concentrations and N:P ratios among the sampled C. paliurus populations. However, there were no significant correlations between soil properties (including organic C, total N and P concentrations) and leaf stoichiometry. The pattern of variation in leaf N concentration across the populations was positively correlated with latitude (24.46° N–32.42° N), but negatively correlated with mean annual temperature (MAT); meanwhile, leaf N concentration and N:P ratios were negatively correlated with mean temperature in January (MTmin) and mean annual frost-free period (MAF). Together, these results suggested that temperature-physiological stoichiometry with a latitudinal trend hold true at both global and regional levels. In addition, the relationships between leaf stoichiometry and climate variables provided information on how leaf stoichiometry of this species may respond to climate change.

Description: Research Highlights: In the current study, we established a method for plant regeneration via somatic embryogenesis (SE) in Koelreuteria paniculata Laxm. for the first time. Background and Objectives: K. paniculata is an important ornamental and medicinal plant in China. However, the plant has difficulty with asexual reproduction, which imposes a limitation on large-scale propagation. Materials and Methods: Embryogenic calluses were induced from stems of aseptic seedlings on induction media. The effects of different media types and concentrations of N6-benzyladenine (BA), α-naphthaleneacetic acid (NAA), and 2,4-dichlorophenoxyacetic acid (2,4-D) on callus induction were examined. Embryogenic calluses were then transferred to Driver-Kuniyuki Walnut (DKW) media containing NAA (0.1–0.2 mg L−1) or 2,4-D (0.5–2.0 mg L−1) to develop somatic embryos. Cotyledon embryos were cultured on DKW media containing NAA (0.1–0.2 mg L−1) until maturation, and were then transferred to 1/2 DKW medium supplemented with 1.0 mg L−1 indole-3-butyric acid (IBA) to produce complete plants. The effects of IBA and NAA on rhizogenesis were then examined by clonal culture. Results: The maximum callus induction frequency (80.25%) was obtained on DKW medium supplemented by 0.5 mg L−1 BA, 0.25 mg L−1 NAA, and 1.5 mg L−1 2,4-D. NAA had a more pronounced effect on somatic embryo growth than did 2,4-D, with a maximum SE frequency (54.75%) observed with 0.1 mg L−1 NAA added to DKW medium. For clonal culture, the highest rooting rate (52%) was observed on 1/4 DKW medium containing 1.5 mg L−1 IBA. Histology studies confirmed the presence of embryogenic calluses and somatic embryos in different stages. Conclusions: This protocol provides a novel method for large-scale propagation of K. paniculata, and creates opportunities for genetic engineering in this species.

Description: The Kunyushan web-spinning sawfly (Cephalcia kunyushanica) is a major pest in the Japanese red pine (JRP, Pinus densiflora) pure forests in the Kunyushan Mountains of China. In this study, four stand types (ST1–4) were identified in plots of JRP pure forests, based on the pest severity index (PSI; ranging from 0–100). The order of infestation ratio in the four type stands was as follows: ST4 〉 ST3 〉 ST2 〉 ST1. We investigated the correlation of C. kunyushanica occurrence with stand characteristics and soil physicochemical properties in the four stand types. The results showed that all stand characteristics were different among the four stand types. Compared with infested plots, healthy (ST1) plots had a higher soil bulk density, and the differences among the groups were significant. Differences in soil water content, non-capillary porosity, and total porosity were significant among the four ST groups. The average organic matter content, total nitrogen (N), and available N were lower in ST1 plots, whereas total potassium (K) was higher compared with other ST groups. In addition, a redundancy analysis suggested that seven (total N, diameter at breast height (DBH), soil water content, bulk density, available K, zinc ion (Zn2+), and stem density) of 24 environmental variables were significantly correlated with the ordinations of C. kunyushanica occurrence. The results provide theoretical guidance for the ecological control of C. kunyushanica, and are also useful for the management of forests in areas where C. kunyushanica is a major pest and where site and stand conditions are similar.

Description: Tree growth in the tropics is strongly influenced by climate. However, reported tree growth responses to climate are largely inconsistent, varying with geographic location, forest type, and tree species. It is thus important to study the growth responses of tropical trees in sites and species that are under-represented so far. Bangladesh, a country influenced by the Asian monsoon climate, is understudied in terms of tree growth response to climate. In the present study, we developed a 121-year-long regional ring-width index chronology of Chukrasia tabularis A. Juss. sampled in two moist forest sites in Bangladesh to investigate tree growth responses to climate in monsoon South Asia. Standard dendrochronological methods were used to produce the ring-width chronologies. The climate sensitivity of C. tabularis was assessed through bootstrap correlation analysis and the stationarity and consistency of climate–growth relationships was evaluated using moving correlation functions and comparing the regression slopes of two sub-periods (1950–1985 and 1986–2015). Tree growth was negatively correlated with the mean, minimum, and maximum temperatures, particularly during the early growing season (March). Likewise, precipitation negatively influenced tree growth in the later growing season (October). Besides, radial growth of Chukrasia sharply ceased in years following strong and moderate El Niño events. In parallel with a significant positive trend in local temperatures, tree growth sensitivity to early growing season (March–April) mean temperatures and July minimum temperatures increased in recent decades. Tree growth sensitivity to October precipitation and April vapor pressure deficit also increased. Overall, climate–growth relationships were stronger during the period 1986–2015 than during 1950–1985. Changes in climate sensitivity might be linked to a warming trend that induced an increase in the dry season length during recent decades. With a further predicted temperature increase at our study sites, our results suggest that radial growth of C. tabularis will further decline in response to climate warming.

Description: The need to tackle international drivers of deforestation has long been acknowledged; but remains little addressed via policy measures. In the European Union (EU), a new policy debate is emerging around the concept of “embodied deforestation”, which targets EU agricultural commodity imports as drivers of deforestation. The notion views deforestation as an externality generated by EU imports associated with tropical deforestation. Our article examines whether this concept represents a shift in tackling international-level drivers of tropical deforestation within EU policy. We also examine, from a networked governance perspective, whether this new debate fuels further fragmentation or rather a move towards a more integrated approach to combating tropical forest loss within EU policy, and what the implications are for other initiatives, such as the climate change related “reducing emissions from deforestation and forest degradation” (REDD+). Our analysis draws on an extensive analysis of EU policy documents and semi-structured interviews with stakeholders and EU decision-makers. We find that, despite growing debate around the concept of embodied deforestation, policy measures necessary to reduce the impact of EU consumption of agricultural commodities associated with tropical deforestation have not yet been developed. We conclude that “embodied deforestation” remains more an idea than reality within EU policy to date, with the burden of responsibility for addressing international deforestation drivers still largely remaining on developing countries. There is still potential, however, for this debate to lead to a more integrated approach to tackling tropical deforestation within EU policy, if it comes to be seen, together with REDD+, as one of a number of linked approaches to EU efforts to combat deforestation.

Description: This study investigates the knowledge and perception of smallholder cocoa farmers on the potential impacts of climate change on cocoa production in Ghana. It addresses opinions on the inclusion of climate change mitigation strategies (such as Reducing Emissions from Deforestation and Forest Degradation—REDD+) into cocoa production, and potential obstacles and roles of stakeholders in ensuring community acceptance of such strategies in a unique multiple land use area—the Krokosua Hills Forest Reserve. Data from the Ghana Meteorological Agency and through survey of 205 cocoa farmers were assessed with Mann-Kendall, Kruskal Wallis and Mann-Whitney tests. Farmers’ perceptions of changes in climate were notably diverse and did not always match historic weather data, but accurately described increases in temperature and drought which are linked to cocoa productivity. Farmers appreciate the importance of tree maintenance for ecosystem services but were skeptical of financially rewarding climate change strategies which favor tree protection. Cultural practices associated with cocoa production encourage carbon release and may pose a threat to the objectives of REDD+. Farmers’ experience on the land, interactions with other farmers, government extension agents and cocoa buyers all influence cocoa agroforestry practices in the area, and communication through existing entities (particularly extension agents) presents a pathway to community acceptance of climate change mitigation strategies. The study recommends reforms in REDD+ strategies to adopt flexible and participatory frameworks to facilitate adoption and acceptability due to pronounced heterogeneity in community perceptions and knowledge of climate change and related issues.

Description: Soil nitrogen (N) and phosphorus (P) shortages limit the growth of shrubs, and P shortage limit the growth of trees in karst ecosystems. Changes in fine root functional traits are the important strategies for plants to respond to such nutrient shortages. However, such responses in karst ecosystems are poorly known. To determine the responses of fine root functional traits to soil N and P changes and define their resource-use strategies in the ecosystem, we tested the specific root length (SRL), root tips over the root biomass (RT/RB), and N concentration (Nroot) in the fine roots of four plant species (two shrubs (Alchornea trewioides and Ligustrum sinense) and two trees (Celtis biondii and Pteroceltis tatarinowii)) during the dry (January) and the wet (July) season. The results showed that the SRL, RT/RB, and Nroot in the fine roots of shrub species were lower than those of tree species, and the three parameters were higher in the wet season than in the dry season. Linear regression models revealed that the SRL, RT/RB, and Nroot of overall species increased with increasing soil N and P concentrations and availabilities, and were positively correlated with increasing rhizosphere soil oxalic acid, microbial biomass carbon (C), and the activities of hydrolytic enzymes. In addition, the individual plant species had unique patterns of the three fine root traits that resulted affected by the change of soil nutrients and biochemistry. Thus, the specific root length, root tips over the root biomass, and N concentrations of fine roots were species-specific, affected by seasonal change, and correlated with soil nutrients and biochemistry. Our findings suggests that fine root functional traits increase the ability of plant species to tolerate nutrient shortage in karst ecosystems, and possibly indicated that a P-exploitative strategy in tree species and an N-conservative strategy in shrub species were exhibited.

Description: In the Southern U.S., timber is transported from harvest sites to mills by many small trucking companies. Few studies have examined the structure and challenges facing these businesses. This study involved interviews with 18 log truck owners operating in the state of Georgia, USA. Participants operated in all forested regions of Georgia and included wood dealers, contract haulers, logging businesses, logging and trucking businesses, and large, diversified trucking businesses. Fleet sizes ranged from zero trucks (recently ceased hauling) to more than 50 log trucks. Log trucks were driven an average of 127,324 km year−1 and delivered an average of 17,410 t year−1. Participants averaged 48% loaded km. Analysis suggests the current combination of average payload, percent-loaded km, and published haul rates make it difficult for log trucking companies to be profitable. The most important challenges faced by log truck owners were a shortage of qualified drivers and rising truck insurance premiums, which were identified as the greatest challenge by 44% and 39% of participants, respectively. Increasing percent-loaded km, reducing turn times at mills and harvest sites, providing driver training, and adopting technologies, such as global positioning system tracking and onboard cameras, could improve transportation efficiency and safety.

Description: Community forestry is required to follow a forest management plan (FMP) to ensure sustainable tree harvesting. However, the role of FMPs or forest bureaucrats’ discretion in guiding harvesting decisions and the resultant effects has not been explored. This paper investigates tree harvesting practices in community forests (CF) and its effects on forest sustainability, using the forest inventory panel dataset for three consecutive periods (2010, 2013 and 2016), together with qualitative information obtained by key informant interviews and a review of records of the community forest users’ group. Harvesting decisions in the CF are largely guided by the decrees or schematic instructions of forest bureaucrats, where the role of the FMP remains highly contested. Whether harvesting decisions should be guided by the prescriptions of the FMP or should be regulated through decrees is a matter of discourse. Forest bureaucrats are arbitrarily reducing harvesting quantities and rarely referring to the prescriptions of the FMP. Consequently, users are compelled to harvest less than half the quantity of trees prescribed in the FMP. Furthermore, they are only allowed to harvest poor quality and dead trees. As a result, the number of good quality trees has increased, while the number of seedlings and saplings has decreased significantly. Although harvesting of saplings and seedlings is a common practice, it is against the provisions of the FMP. Though the current bureaucratic discretion has shown quick short-term effects on the forest stand conditions, the long-term impacts should not be undermined. Our findings will be useful to implementors and policy makers in Nepal and other developing countries with similar circumstances for deciding the tree harvesting. We argue for a rational approach in designing harvesting prescriptions and complying with them rather than regulating harvesting practices through guidelines, circulars and bureaucratic discretion.

Description: Wildfire in declining whitebark pine forests can be a tool for ecosystem restoration or an ecologically harmful event. This document presents a set of possible wildfire management practices for facilitating the restoration of whitebark pine across its range in Western North America. These management actions are designed to enhance whitebark pine resilience and health, while also being effective wildfire management measures. The actions are presented by the three phases of the wildfire continuum: Before, during, and after a wildfire. Current pre-wildfire restoration actions, such as mechanical thinning’s, prescribed burning, and fuel treatments, can also be designed to be fuel treatment activities that allow more effective suppression of wildfires when needed. Three wildfire strategies can be implemented while the wildfire is burning—full suppression, partial suppression, and wildland fire use (letting some fires burn under acceptable conditions)—for protecting valuable whitebark pine trees and for ecosystem restoration. Finally, post-wildfire activities include planting rust-resistant seedlings and monitoring effects of the wildfires. Recommended wildfire management practices for the wildfire continuum are specified by region, site type, and stand type in the last section of this paper.

Description: Elevation gradients offer excellent opportunities to explore the climate sensitivity of vegetation. Here, we investigated elevation patterns of structural, chemical, and physiological traits in tropical tree species along a 1700–2700 m elevation gradient in Rwanda, central Africa. Two early-successional (Polyscias fulva, Macaranga kilimandscharica) and two late-successional (Syzygium guineense, Carapa grandiflora) species that are abundant in the area and present along the entire gradient were investigated. We found that elevation patterns in leaf stomatal conductance (gs), transpiration (E), net photosynthesis (An), and water-use efficiency were highly season-dependent. In the wet season, there was no clear variation in gs or An with elevation, while E was lower at cooler high-elevation sites. In the dry season, gs, An, and E were all lower at drier low elevation sites. The leaf-to-air temperature difference was smallest in P. fulva, which also had the highest gs and E. Water-use efficiency (An/E) increased with elevation in the wet season, but not in the dry season. Leaf nutrient ratios indicated that trees at all sites are mostly P limited and the N:P ratio did not decrease with increasing elevation. Our finding of strongly decreased gas exchange at lower sites in the dry season suggests that both transpiration and primary production would decline in a climate with more pronounced dry periods. Furthermore, we showed that N limitation does not increase with elevation in the forests studied, as otherwise most commonly reported for tropical montane forests.

Description: Agricultural reclamation has been the major threat to land use changes in the Sanjiang Plain, Northeast China, over the past decades. However, spatial and temporal dynamics of land use and landscape, especially in the recent years, are not well known. In this study, land use and landscape pattern changes from 1982 to 2015 were analyzed using remote sensing data by splitting the period into five periods. The results indicated that the largest reduction of forestland area was 648.70 km2 during 1995–2000, and the relative change was −1.84%. The converted area of forestlands to dry farmlands in this period was about 90% of the total reduced forestland area. Marshland areas decreased remarkably by 63.29% and paddy fields increased by 1.78 times from 1982 to 2015. Paddy fields experienced large conversion into dry farmlands during 2005–2010 (1788.57 km2), followed by a reverse conversion from 1995 to 2000 (2379.60 km2). The difference of relative change revealed development speed of paddy field was faster than that of dry farmlands among the five periods. Landscape pattern was analyzed using class- and landscape-level metrics. The landscape diversity index and number of patches increased, which showed that the degrees of the forestland, marshland, and cropland landscape fragmentation were aggravated. Our study provides the effective means of land use dynamic monitoring and evaluation at the landscape level for the existing forestlands and marshlands protection.

Description: The sustainability of “dehesas” is threatened by the Holm oak decline. It is thought that the effects of root rot on plant physiology vary depending on external stress factors. Plant growth and biomass allocation are useful tools to characterize differences in the response to drought and infection. The study of physiological responses together with growth patterns will clarify how and to what extent root rot is able to damage the plant. A fully factorial experiment, including drought and Phytophtora cinnamomi Rands infection as factors, was carried out with Quercus ilex L. seedlings. Photosynthesis, biomass allocation and root traits were assessed. Photosynthetic variables responded differently to drought and infection over time. The root mass fraction showed a significant reduction due to infection. P. cinnamomi root rot altered the growth patterns. Plants could not recover from the physiological effects of infection only when the root rot coincided with water stress. Without additional stressors, the strategy of our seedlings in the face of root rot was to reduce the biomass increment and reallocate resources. Underlying mechanisms involved in plant-pathogen interactions should be considered in the study of holm oak decline, beyond the consideration of water stress as the primary cause of tree mortality.

Description: In the northern Rocky Mountains of the U.S. and Canada, whitebark pine (Pinus albicaulis Engelm.) is a functionally important species in treeline communities. The introduced fungal pathogen Cronartium ribicola, which causes white pine blister rust, has led to extensive whitebark pine mortality nearly rangewide. We examined four treeline communities within the Greater Yellowstone Ecosystem (GYE) to assess structure and composition, whitebark pine prevalence and functional role, differences in growing season mesoclimate among study areas, and blister rust infection incidence. We found that (1) whitebark pine frequently serves as the majority overall, solitary, and leeward tree island conifer; (2) the prevalence of different tree species in the windward position in tree islands, and thus their potential as tree island initiators, may be predicted from their relative abundance as solitary trees; and (3) white pine blister rust infection incidence ranged from 0.6% to 18.0% across study areas. White pine blister rust poses a threat to treeline development and structure and the provision of ecosystem services in the GYE. Increasing blister rust resistance in nearby subalpine whitebark pine communities through seedling planting or direct seeding projects should eventually result in higher levels of blister rust resistance in whitebark pine in treeline communities.

Description: We compared the effects of hydrophilic polymer amendments on drought and salt tolerance of Metasequoia glyptostroboides Hu and W.C.Cheng seedlings using commercially available Stockosorb and Luquasorb synthetic hydrogels and a biopolymer, Konjac glucomannan (KGM). Drought, salinity, or the combined stress of both drought and salinity caused growth retardation and leaf injury in M. glyptostroboides. Under a range of simulated stress conditions, biopolymers and synthetic hydrogels alleviated growth inhibition and leaf injury, improved photosynthesis, and enhanced whole-plant and unit transpiration. For plants subjected to drought conditions, Stockosorb hydrogel amendment specifically caused a remarkable increase in water supply to roots due to the water retention capacity of the granular polymer. Under saline stress, hydrophilic polymers restricted Na+ and Cl− concentrations in roots and leaves. Moreover, root K+ uptake resulted from K+ enrichment in Stockosorb and Luquasorb granules. Synthetic polymers and biopolymers increased the ability of M. glyptostroboides to tolerate combined impacts of drought and salt stress due to their water- and salt-bearing capacities. Similar to the synthetic polymers, the biopolymer also enhanced M. glyptostroboides drought and salt stress tolerance.

Description: Scientific studies have shown that mixed forests of silver fir (Abies alba Mill.) and European beech (Fagus sylvatica L.) provide higher ecosystem services than monospecific forests. Mixed forests are known for their high resilience to climate change impacts and superior biodiversity compared to monospecific forests. Despite this superiority, the transformation from monospecific to mixed forests can meet socio-technical challenges that are manifested in dissent or even in conflicts. The integration of stakeholders and citizens plays a key role in analyzing their perceptions and views of forest transformation. Their knowledge is required to co-design and implement socially acceptable options and pathways to increase the share of mixed forests. Based on a survey in Southwest Germany, we analyzed stakeholders’ and citizens’ perceptions of ecosystem services of monospecific and mixed forests of silver fir and beech. The findings show that people believe that mixed forests provide better cultural, regulating, and supporting ecosystem services than monospecific forests. However, provisioning services were perceived as being equally or even better provided by monospecific forests. The assumed abundance of old trees and the feelings of pleasantness especially influenced the superior perception of ecosystem services provided by mixed forests. The results indicate that there is public support for the transformation of monospecific silver fir and beech forests into mixed forests in Southwest Germany.

Description: Time series of repeat aerial photographs currently span decades in many regions. However, the lack of calibration data limits their use in forest change analysis. We propose an approach where we combine repeat aerial photography, tree-ring reconstructions, and Bayesian inference to study changes in forests. Using stereopairs of aerial photographs from five boreal forest landscapes, we visually interpreted canopy cover in contiguous 0.1-ha cells at three time points during 1959–2011. We used tree-ring measurements to produce calibration data for the interpretation, and to quantify the bias and error associated with the interpretation. Then, we discerned credible canopy cover changes from the interpretation error noise using Bayesian inference. We underestimated canopy cover using the historical low-quality photographs, and overestimated it using the recent high-quality photographs. Further, due to differences in tree species composition and canopy cover in the cells, the interpretation bias varied between the landscapes. In addition, the random interpretation error varied between and within the landscapes. Due to the varying bias and error, the magnitude of credibly detectable canopy cover change in the 0.1-ha cells depended on the studied time interval and landscape, ranging from −10 to −18 percentage points (decrease), and from +10 to +19 percentage points (increase). Hence, changes occurring at stand scales were detectable, but smaller scale changes could not be separated from the error noise. Besides the abrupt changes, also slow continuous canopy cover changes could be detected with the proposed approach. Given the wide availability of historical aerial photographs, the proposed approach can be applied for forest change analysis in biomes where tree-rings form, while accounting for the bias and error in aerial photo interpretation.

Description: Community-based natural resource management (CBNRM) is a widely used approach aimed at involving those utilizing resources in their management. In Madagascar, where forest decentralization has been implemented since the 1990s to spur local resource users’ involvement in management processes, impacts remain unclear. This study aimed to investigate farmers’ perceptions and practices regarding forest use under various forest governance systems, using a participatory gaming approach implemented in the Zahamena region of Madagascar. We report on (i) the conceptual models of the Zahamena socio-ecological system; (ii) the actual research tool in the form of a tabletop role-playing game; and (iii) main outcomes of the gaming workshops and accompanying research. The results allow the linking of game reality with real-world perceptions based on game debriefing discussions and game workshop follow-up surveys, as well as interviews and focus group research with other natural resource users from the study area. Results show that the Zahamena protected area plays the role of buffer zone by slowing down deforestation and degradation. However, this fragile barrier and CBNRM are not long-term solutions in the face of occurring changes. Rather, the solution lies in one of the main causes of the problem: agriculture. Further use of tools such as participatory gaming is recommended to enhance knowledge exchange and the development of common visions for the future of natural resource management to foster resilience of forest governance.

Description: Erythrophleum fordii Oliv. is a valuable rosewood species indigenous to the tropical and warm sub-tropical zones of Vietnam, Laos, and South China. The natural forests have been heavily fragmented mostly due to over-exploitation and over-utilization, and alteration to croplands and fast-growing plantations. Therefore, it has been included in the IUCN Red List of Endangered Species as an endangered species. In the present study, genetic diversity and population genetic structure of 11 populations were estimated by SSR makers in South China. Five high polymorphic loci were studied with a total of 34 alleles, among which, seven were private alleles. The mean number of alleles per locus (A), the mean number of efficient alleles per locus (Ae), the observed (Ho) and expected (He) heterozygosity, and Shannon’s index (I) of the 11 populations were 3.40, 2.31, 0.52, 0.56, and 0.90, respectively. Correlation analysis between genetic parameters and geographical factors showed that He and I were in significant negative correlation with longitude, indicating that genetic diversity of E. fordii reduced gradually from West to East in south China. FIS of eight populations with above five samples was on average 0.01, most loci conformed to Hardy-Weinberg equilibrium in these populations; their genetic differentiation coefficient (FST) was 0.18, indicating that genetic differentiation among populations was relatively low and there existed 18% genetic variation among populations. Gene flow (Nm) between these populations was 1.28. The Mantel test showed that genetic distance was not significantly correlated with geographical distance (p 〉 0.05). It was concluded that populations with high genetic diversity or private alleles, especially Longmen, Wuming and Pingxiang populations should be a priority for in situ conservations, meanwhile more populations and as many families as possible in each population should be collected for ex situ conservations of germplasm resources of this species in the future.

Description: In the central and eastern United States, many forest ecosystems have undergone recent shifts in composition and structure that may conflict with contemporary management objectives. Long-term forest inventory data were used to determine patterns of forest succession over a 48-year period for four forest types in mid-Missouri: bottomlands, dry ridge and slope, glade-like, and mesic slopes. All forest types increased in stand basal area and overstory quadratic mean diameter through time, with concomitant decreases in the number of midstory trees. Sugar maple (Acer saccharum Marshall) increased in importance value on dry ridge and slope and mesic slope forest types, largely due to the accumulation of trees in smaller diameter classes. White oak (Quercus alba L.) increased in overstory basal area in dry ridge and slope plots through the duration of the study, whereas black oak (Quercus velutina Lam.) and Shumard oak (Quercus shumardii Buckley) decreased in overstory density and basal area through time. Oak stems were nearly absent from the midstory across forest types in the recent sampling, suggesting future challenges for maintaining oak-dominated canopies following attrition of canopy trees through time on upland forest types. In glade-like plots, eastern redcedar (Juniperus virginiana L.) increased in both overstory density and basal area through time, and Shumard oak decreased in density. The importance value of chinkapin oak (Quercus muehlenbergii Engelm.) in the overstory decreased through time in glade-like plots, largely due to the increase in density of eastern redcedar rather than the loss of chinkapin oak from the overstory. The patterns of succession in this forest landscape of mid-Missouri suggest that forest management may be needed to address two common contemporary concerns: (1) the need for increasing oak advance reproduction and recruitment to maintain oak as a canopy species; and (2) reducing eastern redcedar encroachment for glade restoration and management.

Description: Understanding perceptions and attitudes of forest managers toward climate change and climate adaptive forest management is crucial, as they are expected to implement changes to forest resource management. We assessed the perceptions of forest managers toward climate adaptive forest management practices through a survey of forest managers working in private firms and public agencies in New England and the Klamath ecoregion (northern California and southwestern Oregon). We analyzed the motivations, actions, and potential barriers to action of forest managers toward climate adaptive forest management practices. Results suggest that managing for natural regeneration is the most common climate adaptive forest management approach considered by forest managers in both regions. Lack of information about the best strategies for reducing climate change risks, lack of education and awareness among the clients, and perceived client costs were forest managers’ primary barriers to climate adaptive management. Our findings suggest useful insights toward the policy and program design in climate adaptive forest management for both areas.

Description: To anticipate European climate scenarios for the end of the century, we explored the climate gradient within the REINFFORCE (RÉseau INFrastructure de recherche pour le suivi et l’adaptation des FORêts au Changement climatiquE) arboreta network, established in 38 sites between latitudes 37° and 57°, where 33 tree species are represented. We aim to determine which climatic variables best explain their survival and growth, and identify those species that are more tolerant of climate variation and those of which the growth and survival future climate might constrain. We used empirical models to determine the best climatic predictor variables that explain tree survival and growth. Precipitation-transfer distance was most important for the survival of broadleaved species, whereas growing-season-degree days best explained conifer-tree survival. Growth (annual height increment) was mainly explained by a derived annual dryness index (ADI) for both conifers and broadleaved trees. Species that showed the greatest variation in survival and growth in response to climatic variation included Betula pendula Roth, Pinus elliottii Engelm., and Thuja plicata Donn ex D.Don, and those that were least affected included Quercus shumardii Buckland and Pinus nigra J.F.Arnold. We also demonstrated that provenance differences were significant for Pinus pinea L., Quercus robur L., and Ceratonia siliqua L. Here, we demonstrate the usefulness of infrastructures along a climatic gradient like REINFFORCE to determine major tendencies of tree species responding to climate changes.

Description: Jatropha is promoted as a pro-poor bioenergy plant, while basic information about its productivity, age of maximum production, and oil content are missing. This study aims to determine the seed yield (dry weight) for three INIAP elite jatropha accessions, and to evaluate the changes in physical and chemical seed traits at the different fruit ripening stage in a split-plot design. Maximum seed production occurred four years after planting for the accessions CP041 and CP052, while for accession CP054, it occurred after the first year. CP041 was the most productive, with a mean of 316.46 g tree−1 year−1 (±76.50) over the 8-year study period. No significant differences in oil content were found among accessions, fruit ripening stage, and their respective interactions. Seed moisture content decreased drastically as the fruit ripening stage increased, from 40.5% ± 1.0% at fruit ripening stage 1 (greenish-yellow) down to 13.8% ± 0.4% at fruit ripening stage 4 (black-brown). No significant differences in seed weight were found among accessions, but it decreased as maturation progressed. Yellow fruits (stage 2) were the heaviest (62.4 g ± 1.5 g) and the black-brown fruits the lightest (44.3 g ± 1.9 g). The oil content (%) increased with seed weight up to the point of 58.3 g, but then decreased for heavier seeds.

Description: To date, numerous public- and private-sector efforts, commitments, and initiatives to reduce commodity-driven deforestation have emerged. In and of themselves, these elements—namely REDD+ programs, jurisdictional approaches (JAs), and private sector commitments—are necessary, but they are not sufficient to reduce deforestation. When operating together, however, these efforts have the potential to significantly reduce commodity-driven deforestation. This research aimed to determine whether and where REDD+ programs, JAs, and private sector commitments overlap in what are termed “trifecta jurisdictions”. Considering that each element possesses features that can enhance and complement those of the others, the authors hypothesized that—but did not ascertain whether—trifecta jurisdictions present the greatest potential to reduce commodity-driven deforestation. A total of 13 trifecta jurisdictions and six bifecta jurisdictions—where two of the three elements are present—were identified by: compiling a dataset of REDD+ programs, JAs, and private sector commitments; evaluating all potential options against established criteria; and categorizing them according to trifecta or bifecta jurisdiction status. The fact that a majority of trifecta and bifecta jurisdictions are located in countries with the most tropical tree cover loss is also significant in that it highlights the presence of these elements where most needed, and how high deforestation rates might be attracting REDD+ program, JA, and private sector commitment activities. Although many of the REDD+ programs, JAs, and private sector commitments are relatively nascent and their ability to collectively reduce deforestation is not yet clearly evident, this article posited that synergistic potential is greatest in trifecta and bifecta jurisdictions and that efforts should be made to greater align these elements.

Description: Crown size estimations are of vital importance in forest management practice. This paper presents nonlinear models that were developed for crown width prediction of Black pine (Pinus nigra Arn.) natural, pure, even-aged stands in Olympus Mountain, central Greece. Using a number of measured characteristics at tree and plot level from 66 sample plots as independent variables, an attempt was made to predict crown width accurately, initially based on Least Square Analysis. At the second stage, nonlinear mixed effect modeling was performed in order to increase the fitting ability of the proposed models and to deal with the lack of between observations independence error assumption. Based on the same form, a generalized crown width model was developed by including six main regressors, such as the diameter at breast height, the total height, the canopy base height, the basal area, the relative spacing index and the diameter to quadratic mean diameter ratio, while at the final stage, the same model was expanded to mixed-effect. The proposed models were evaluated against independent crown width sample observations that were also obtained from the study area. The results showed that the two types of mixed-effect models performed equally well and, therefore, we propose those for use in forestry practice. Furthermore, the exact contribution of each inherent variable in crown width allometry was evaluated, thus providing a framework to facilitate field measurements for forest management predictions.

Description: Linking climate action with sustainable development goals (SDGs) might incentivize social and political support to forest conservation. However, further examination of the conceptual entry points for linking efforts for reducing forest-based emissions with those for delivering SDGs is required. This review paper aims to contribute to fulfilling this research need. It provides insights into the links between conserving forests for climate change mitigation and peacebuilding. Specifically, the paper examines opportunities to harness climate finance for conserving forests and achieving long-lasting peace and sustainable food. It does so via a literature review and the examination of the Orinoquia region of Colombia. The findings from the literature review suggest that harnessing climate finance for conserving forests and peacebuilding is, in theory, viable if the activities are designed in accordance with social, institutional, and economic factors. Meanwhile, the Orinoquia region provides evidence that these two seemingly intractable problems are proposed to be solved together. At a time when efforts for reducing forest-based emissions are being designed and targeted at (post-) conflict areas in Colombia and elsewhere, the paper’s findings might demonstrate the compatibility of programs aimed at reducing forest-based emissions with efforts relating to peacebuilding and sustainable food to both environmental and non-environmental government agencies.

Description: The forest canopy is the medium for energy and mass exchange between forest ecosystems and the atmosphere. Remote sensing techniques are more efficient and appropriate for estimating forest canopy cover (CC) than traditional methods, especially at large scales. In this study, we evaluated the CC of black locust plantations on the Loess Plateau using random forest (RF) regression models. The models were established using the relationships between digital hemispherical photograph (DHP) field data and variables that were calculated from satellite images. Three types of variables were calculated from the satellite data: spectral variables calculated from a multispectral image, textural variables calculated from a panchromatic image (Tpan) with a 15 × 15 window size, and textural variables calculated from spectral variables (TB+VIs) with a 9 × 9 window size. We compared different mtry and ntree values to find the most suitable parameters for the RF models. The results indicated that the RF model of spectral variables explained 57% (root mean square error (RMSE) = 0.06) of the variability in the field CC data. The soil-adjusted vegetation index (SAVI) and enhanced vegetation index (EVI) were more important than other spectral variables. The RF model of Tpan obtained higher accuracy (R2 = 0.69, RMSE = 0.05) than the spectral variables, and the grey level co-occurrence matrix-based texture measure—Correlation (COR) was the most important variable for Tpan. The most accurate model was obtained from the TB+VIs (R2 = 0.79, RMSE = 0.05), which combined spectral and textural information, thus providing a significant improvement in estimating CC. This model provided an effective approach for detecting the CC of black locust plantations on the Loess Plateau.

Description: Certainty over warming-induced biomass accumulation is essential for addressing climate change. However, no previous meta-analysis has investigated this accumulation across the whole of China; also unclear are the differences between herbaceous and woody species and across plant phylogeny, which are critical for corresponding re-vegetation. We extracted data from 90 field-based experiments to reveal general patterns and driving factors of biomass responses all over China. Based on traditional meta-analyses, a warmer temperature significantly increased above- (10.8%) and below-ground (14.2%) biomass accumulation. With increasing warming duration (WarmD) and plant clade age, both above-ground and below-ground biomass showed significant increases. However, for herbaceous versus woody plants, and the whole community versus its dominant species, responses were not always constant; the combined synergies would affect accumulative response patterns. When considering WarmD as a weight, decreases in total above-ground biomass response magnitude were presented, and the increase in below-ground biomass was no longer significant; notably, significant positive responses remained in tree species. However, if phylogenetic information was included in the calculations, all warming-induced plant biomass increases were not significant. Thus, it is still premature to speculate whether warming induces biomass increases in China; further long-term experiments are needed regarding phylogeny-based responses and interspecies relations, especially regarding woody plants and forests.

Description: Observed conversion of xerophytic warm genera species to mesophytic cool genera species in North America’s Eastern Deciduous Forest (EDF) suggests species composition is in disequilibrium with recent climatic warming. However, increasing annual average temperatures is an oversimplification of long-term climatic change and the importance of climate variance is often neglected. Seven-year moving averages and standard deviations of annually averaged maximum temperatures, minimum temperatures, daily precipitation, and vapor pressure deficits (VPD) in West Virginia, USA were quantified over a 111-year period of record (1906–2016). Maximum temperatures decreased significantly (−5.3%; p 〈 0.001), minimum temperatures increased significantly (7.7%; p 〈 0.001), and precipitation increased (2.2%; p = 0.107). Additionally, maximum temperature variance decreased (−17.4%; p = 0.109), minimum temperature variance decreased significantly (−22.6%; p = 0.042), and precipitation variance increased significantly (26.6%; p = 0.004). Results indicate a reduced diurnal temperature range and significant reductions in estimated VPD (10.3%; p 〈 0.001) that imply increased relative humidity, cloud cover, and soil moisture that may support increasingly abundant mesophytic cool genera species. Feedback mechanisms associated with extensive changes in land use, fire suppression, and browser population may have exacerbated climatic changes. Long-term assessments of changing climatic averages and variance are needed to ensure sustainability of forest ecosystem services, health, and productivity in a swiftly changing climate across the broader EDF region and similar temperate forest ecosystems globally.

Description: Climate change has an inevitable impact on tree radial growth, particularly at mountain timeberlines. To understand climate effects on conifer radial growth in the central Hengduan Mountains, and the potential impacts of future climate change on conifer forests, we studied the growth responses to climate variables in Abies georgei, the major tree species of conifer forest in the Hengduan Mountains. We collected tree ring samples from four sites near the timberlines and analyzed the relationship between principle components (PC#1) of four chronologies and climatic variables (monthly mean temperature and monthly total precipitation) by using response function analysis (RFA), redundancy analysis (RDA), and moving interval analysis (MIA). A. georgei growth was affected by both temperature (positive effects) and precipitation (negative effects). Specifically, the radial growth of A. georgei was significantly and positively correlated with current July (by 6.1%) and previous November temperature (by 17.3%) (detected by both RFA and RDA), while precipitation of current June (by 6.6%) and September (by 11.7%) inhibited tree growth (detected by RDA). More rapid warming in the most recent 20 years (1990–2010) clearly enhanced growth responses to July and November temperature, whereas the relationship was weakened for June and September precipitation, according to MIA. Under the climate trend of the study area, if the increasing temperature could offset the negative effects of excessive precipitation, A. georgei radial growth would likely benefit from warming.

Description: To provide a theoretical basis for developing intensive cultivation practices for Populus tomentosa plantations, the leaf phenology variation within the canopy and its relationship with transpiration of well-watered P. tomentosa tree in a dense plantation were investigated. The variation in canopy light interception, indicated by the ratio between net radiation under (Rn-u) and above (Rn-a) canopy, with leaf development was also studied. During the growing season, the achievement of maximum leaf number tended to be later in higher parts of the canopy. In the lower and middle canopy, the leaf number maximized earlier in the east-facing side than in the west-facing side, but this difference disappeared in the upper canopy. The Rn-u/Rn-a was stable in May, but declined and then varied steadily until late August. Generally, in May, the crop coefficient (Kcb) of the tree reached its highest level and was not correlated with leaf area (LA) in all layers (p 〉 0.05). However, it increased linearly (p 〈 0.001) with LA in the layers above a canopy height of 3 m from June to late August, and most of its variation was explained by LA in the 5–7 m layer. After late August, Kcb decreased linearly with decreasing LA in all layers (p 〈 0.001). Consequently, a temporal ecological strategy seems to be adopted by P. tomentosa leaves in different layers and azimuthal sides for efficient light acquisition. The contribution of the different canopy layers to tree transpiration can vary, with the leaves in the upper and all layers mainly controlling transpiration in summer and in spring and autumn, respectively.

Description: The response mechanism of the tree stem radius variation to hydro-thermal factors is complex and diverse. The changes of TWD (tree water deficit-induced stem shrinkage) and GRO (growth-induced irreversible stem expansion) are respectively driven by different factors, so that their responses to hydro-thermal factors are different. The stem radius variation and its matching hydro-thermal factors experimental data was measured and determined at 0.5 h time scale in larch (Larix gmelini Rupr.) forest of the Daxing’anling region of the most northeastern part of China. Response characteristics of the stem radius variation to hydro-thermal factors have been found by analyzing the data under different time windows. The stem radius variation mainly responded to the changes in precipitation and relative humidity. The main driving factors for TWD were sap flow density and solar radiation. The response of GRO to hydro-thermal factors was complex, varied a lot under different time scales. During the analysis of the response of tree radial growth, changes of the stem radius can be divided to TWD and GRO to implement separate studies on their responses to hydro-thermal factors. In this way, it becomes easier to discover the response of TWD under drought stress and the responding mechanism of GRO to hydro-thermal factors.

Description: Historically, the expansion of soy plantations has been a major driver of land-use/cover change (LUCC) in Brazil. While a series of recent public actions and supply-chain commitments reportedly curbed the replacement of forests by soy, the expansion of the agricultural commodity still poses a considerable threat to the Amazonian and Cerrado biomes. Identification of areas under high risk of soy expansion is thus paramount to assist conservation efforts in the region. We mapped the areas suitable for undergoing transition to soy plantations in the Legal Amazon with a machine-learning approach adopted from the ecological modeling literature. Simulated soy expansion for the year 2014 exhibited favorable validation scores compared to other LUCC models. We then used our model to simulate how potential future infrastructure improvements would affect the 2014 probabilities of soy occurrence in the region. In addition to the 2.3 Mha of planted soy in the Legal Amazon in 2014, our model identified another 14.7 Mha with high probability of soy conversion in the region given the infrastructure conditions at that time. Out of those, pastures and forests represented 9.8 and 0.4 Mha, respectively. Under the new infrastructure scenarios simulated, the Legal Amazonian area under high risk of soy conversion increased by up to 2.1 Mha (14.6%). These changes led to up to 11.4 and 51.4% increases in the high-risk of conversion areas of pastures and forests, respectively. If conversion occurs in the identified high-risk areas, at least 4.8 Pg of CO2 could be released into the atmosphere, a value that represents 10 times the total CO2 emissions of Brazil in 2014. Our results highlight the importance of targeting conservation policies and enforcement actions, including the Soy Moratorium, to mitigate future forest cover loss associated with infrastructure improvements in the region.

Description: Using Non-invasive Micro-test Technology (NMT), the Na+, K+ and H+ flux profiles in the root meristem regions were investigated in Nitraria sibirica Pall. seedlings under different NaCl concentrations. NaCl stress increased the K+ and Na+ contents in the roots of N. sibirica seedlings. NaCl stress significantly increased the steady Na+ efflux from the N. sibirica seedling roots. Steady K+ effluxes were measured in the control roots (without NaCl) and in the roots treated with 200 mM NaCl, and no significant differences were observed between the two treatments. The steady K+ efflux from roots treated with 400 mM NaCl decreased gradually. NaCl treatment significantly increased the H+ influx. Pharmacological experiments showed that amiloride and sodium vanadate significantly inhibited the Na+ efflux and H+ influx, suggesting that the Na+ efflux was mediated by a Na+/H+ antiporter using energy provided by plasma membrane H+-ATPase. The NaCl-induced root K+ efflux was inhibited by the K+ channel inhibitor tetraethylammonium chloride (TEA), and was significantly increased by the H+-ATPase inhibitor sodium vanadate. The NaCl-induced K+ efflux was mediated by depolarization-activated outward-rectifying K+ channels and nonselective cation channels (NSCCs). Under salt stress, N. sibirica seedlings showed increased Na+ efflux due to increased plasma membrane H+-ATPase and Na+/H+ antiporter activity. High H+ pump activity not only restricts the Na+ influx through NSCCs, but also limits K+ leakage through outward-rectifying K+ channels and NSCCs, leading to maintenance of the K+/Na+ balance and higher salt tolerance.

Description: The Natura 2000 network, which is one of the largest networks of protected areas in the world, is the core pillar in the European Union’s biodiversity conservation policy. To achieve the national enforcement of Natura 2000 and to overcome implementation problems, effective policy measures are needed, and participation among different stakeholders is required. The aim of this paper was to evaluate the process of formulation of the Natura 2000 Management Program (2015–2020) in Slovenia based on a set of criteria and indicators for the evaluation of a participatory process, and to present the differences between the stakeholders’ evaluations according to their role in the implementation process. For that purpose, stakeholders were divided into two groups—stakeholders from project partner’s institution, and others. The research was done in two steps: First, in-depth semi-structured interviews with 17 representatives of the key stakeholders’ institutions or organizations that were involved in the formulation of the Natura 2000 Management Program were carried out; in the second, a survey with 266 stakeholders involved in the formulation and decision-making process was conducted. Overall, the results show that the participatory process was well organized, independent and fair; however, not all of the requisite conditions for successful participation were fulfilled, as was shown with the sub-criteria of transparency. The only difference between the groups exists in the evaluations of the sub-criteria transparency of the process. The group of stakeholders from the project’s partner institutions were more satisfied with the transparency of the process, as the average value was 3.36, compared to the others where the average value of satisfaction was 2.80. This indicates the need for an improved, novel, and innovative approach that leads to multi-level governance.

Description: Every year there are changes in the register of fungicides available for forestry. It is proactive to develop a new strategy to minimise the application of chemical methods and replace them with natural and biological fungal control options. This study compares the influence after one growing season in a bare-root forest nursery of (a) effective microorganisms (EM) consisting of mixed cultures of beneficial and naturally-occurring microorganisms, (b) the organic fertilizer Actifos (Act), and (c) the mineral fertilizer Busz Forte (BF) on the growth and mycorrhizal colonization of two common forest deciduous tree species: Fagus sylvatica and Quercus robur. None of the analysed growth parameters (root collar diameter, length of shoots and roots, dry mass of shoots, and roots) of either tested tree species differed significantly among treatments. For both tree species, seedlings treated with EM exhibited partnerships with a smaller species richness of mycorrhizae than did seedlings in other treatments. Moreover, EM treatment significantly increased the abundance of non-vital root tips for both species. By contrast, BF exerted a negative effect on F. sylvatica non-vital mycorrhiza abundance. Based on morphological and molecular identification, a total of 11 ectomycorrhizal (ECM) fungal taxa were detected in this study; three species (Peziza ostracoderma, Scleroderma areolatum and Cenococcum-like) were shared between both plant species. Across treatments, the most abundant ECM fungal species on F. sylvatica roots were Pezizaceae sp. (51.1%) and Hebeloma sp. (38.1%), while Peziza ostracoderma (26.8%), Naucoria salicis (24.1%), and Scleroderma areolatum (16.9%) were the most abundant taxa on Q. robur seedling roots. Our data indicate a negative effect of EM on ectomycorrhizal colonisation and on species richness of ECM fungi associated with F. sylvatica and Q. robur seedlings. None of the tested products had a negative effect on seedling growth, but seedlings treated with EM were characterised by a significant higher abundance of non-vital mycorrhizae.

Description: Understanding the association between soil organic carbon (SOC) and texture under different climatic conditions is important for assessing the effects of future climate changes on SOC stocks. In this study, we conducted a climatic gradient experiment covering three climate types (humid, sub-humid, and semi-arid) with a steep rainfall ranging from 345 to 910 mm, and specifically determined SOC dynamics, clay content, and vegetation and soil characteristics. The results showed that, from semi-arid to humid regions, SOC stocks, SOC, and clay content increased synchronously and were closely related in layers of depths of both 0–10 and 10–20 cm. In contrast, under similar climatic conditions, SOC dynamics were mainly affected by vegetation and soil characteristics, especially total nitrogen and total phosphorus dynamics, but not the soil clay content. Therefore, these results suggest that the relationship between SOC stocks and clay content depended on scale sizes. Specifically, on a larger scale with different climatic gradients, the climate may partly determine the changes in SOC and clay dynamics, whereas, at a smaller scale where climate type does not vary considerably, the changes in SOC stocks and clay content may be related to vegetation diversity and soil nutrient dynamics. These results may contribute to future model development and the projection of changes in soil carbon storage.

Description: The cycling of essential nutrients is central to mangrove productivity. A mass balance shows that mangroves rely on soil ammonification, nitrification, and dissimilatory reduction to ammonium for available nitrogen. Mangroves are often nutrient limited and show tight coupling between nutrient availability and tree photosynthesis. This relationship and, thus, forest productivity can be disrupted by various disturbances such as deforestation, changes in hydrology due to impoundments, land-use change, increasing frequency and intensity of storms, increasing temperatures, increasing atmospheric CO2 concentrations, and a rising sea-level. Deforestation and hydrological changes are the most devastating to soil nutrient-plant relations and mangrove productivity. Land-use changes can result in positive and negative impacts on mangroves and can also results in increasing frequency of storms and intensity of storms. Increasing temperatures and atmospheric CO2 levels have an initially enhanced effect on mangroves and microbial transformation rates of nitrogen and phosphorus. The effects of rising seas are complex and depend on the local rate of sea-level rise, the soil accretion rate, the subsidence or uplift rate, and the tidal position. If mangroves cannot keep pace with a sea-level rise, seaward mangroves will likely drown but landward mangroves will expand and show enhanced growth and more rapid nutrient cycling if space permits.

Description: Limber pine (Pinus flexilis James) co-evolved with the mountain pine beetle (Dendroctonus ponderosae Hopkins; MPB) and is now also challenged by the non-native pathogen Cronartium ribicola (J.C. Fisch.) that causes the lethal disease white pine blister rust (WPBR). Previous research suggests that trees infected with WPBR can be preferred hosts for MPB. Using resin duct traits associated with MPB resistance, we tested for a relationship between resistance to MPB and WPBR in limber pine, in the absence of either biological agent. These analyses will help evaluate if MPB historically may have contributed to natural selection for WPBR resistance in advance of WPBR invasion, and could help explain the unusually high frequency of the dominant Cr4 allele for complete resistance to WPBR in limber pine populations of the Southern Rocky Mountains. Resin duct production, density and relative duct area did not differ between healthy trees previously inferred to carry the dominant Cr4 allele and trees that lack it at 22 sites, though some duct traits varied with elevation. MPB resistance does not appear to have played an evolutionary role in contributing to the high frequency of Cr4 in naïve populations, however, MPB may affect the future evolution of resistance to WPBR in the pines where the two pests coincide and WPBR will affect forest recovery after MPB epidemics. MPB-WPBR interactions in a changing climate will affect the future trajectory of limber pine.

Description: Bioenergy can produce at least 25% of the global energy demand to combat climate change through reducing emissions in the energy sector. However, information on the bioenergy production potential of woody species and their suitability for silviculture on various soils in the humid tropics is limited. This review aims to identify tree species suitable for bioenergy production under these conditions. Data were compiled from 241 publications and nine freely available databases to assess environmental and silvicultural information on tropical tree species. Energy outputs were derived from the estimated productivity of the reviewed species and ranged from 0.2 to 24.0 Mg biomass ha−1 yr−1, 0.1 to 9.0 Mg bio-oil ha−1 yr−1, and 0.2 to 20.0 Mg sugar ha−1 yr−1, equivalent to an energy yield between 2 and 444 GJ ha−1 yr−1. As such, these bioenergy yields are within the range reported for the lignocellulosic biomass of energy crops cultivated in Europe, the USA, and Brazil. Our review identified some high-yielding species (e.g., Dyera polyphylla (Miq.) Steenis, Metroxylon sagu (Rottb.), Pongamia pinnata (L.)) and leguminous species that could be beneficial in mixed stands (e.g., Elaeis oleifera (Kunth) and Pongamia pinnata) or are suitable species to grow on wet or re-wetted peatland (Dyera polyphylla). However, there are limitations to cultivate woody bioenergy species on wet peatland. Sustainable methods for managing and harvesting forests, particularly on wet or re-wetted peatland, need to be developed.

Description: We simulated Austrian forests under different sustainable management scenarios. A reference scenario was compared to scenarios focusing on the provision of bioenergy, enhancing the delivery of wood products, and reduced harvesting rates. The standing stock of the stem biomass, carbon in stems, and the soil carbon pool were calculated for the period 2010–2100. We used the forest growth model Câldis and the soil carbon model Yasso07. The wood demand of all scenarios could be satisfied within the simulation period. The reference scenario led to a small decrease of the stem biomass. Scenarios aiming at a supply of more timber decreased the standing stock to a greater extent. Emphasizing the production of bioenergy was successful for several decades but ultimately exhausted the available resources for fuel wood. Lower harvesting rates reduced the standing stock of coniferous and increased the standing stock of deciduous forests. The soil carbon pool was marginally changed by different management strategies. We conclude that the production of long-living wood products is the preferred implementation of climate-smart forestry. The accumulation of carbon in the standing biomass is risky in the case of disturbances. The production of bioenergy is suitable as a byproduct of high value forest products.

Description: An effective way to reduce off-road traffic in forests is to implement greater distances between skid trails. However, this implies that trees beyond the boom reach of the harvester need to be felled motor manually before being winched to the skid trail, for example using a remote-controlled mini forestry crawler (MFC). They are only a few local studies which have evaluated the performance of such MFCs. The use of MFCs for wood extraction operations in mixed soft- and hardwood stands is presented in this study conducted in Southwestern Germany. The aim of this study was to analyze the productivity, costs, and selected environmental impacts of mini forestry crawlers during winching operations through a time study. Using statistical regression, time consumption was analyzed in order to determine significant explanatory variables. Environmental impacts were evaluated using the life cycle assessment (LCA) methodology with Umberto software. The mean net cycle time was 4.82 min and the net productivity rate was 7.77 m3 by productive machine hour (PMH0). Explanatory variables which significantly affected the net cycle time were the winched volume, the number of trees per load, and winching distance. Environmental analysis showed that inputs of fossil energy were mostly due to diesel and lubricant consumption. Raw materials for machine manufacture and maintenance showed the highest impact in human toxicity potential category. The MFCs showed good environmental performances, but the harvesting system should become more productive in order to be more cost effective.

Description: A positive nutrient balance is crucial to sustaining forest productivity. Differences in stand densities usually mean different aboveground biomass stocks and different proportions of tree compartments. These differences can be reflected in the different macronutrient stocks between stands of different densities, because various tree compartments have different element concentrations. In this study, 82-year-old stands of Scots pine were compared, and specifically, the concentrations of the elements in tree compartments and the amounts of macronutrients in aboveground biomass were compared. The nutrients considered in this study were nitrogen, phosphorus, potassium, calcium, magnesium, and sulfur. A positive correlation between stand density and the level of stored macronutrients was found for nitrogen, phosphorus, and potassium. This result means that forest managers can influence nutrient balances by regulating stand densities or by harvesting methods (SOH: stem-only harvesting or WTH: whole-tree harvesting).

Description: Almost a decade since the establishment of Reducing Emissions from Deforestation and Degradation (REDD+), this study investigates the extent to which REDD+ projects are delivering on the promise of co-benefits and the elusive ‘triple-win’ for climate, biodiversity, and local communities. The Climate, Community and Biodiversity Alliance (CCB) is among several leading REDD+ certification standards that are designed to support the delivery of social and environmental co-benefits, and ‘socially-just’ carbon. This study uses an in-depth content analysis of 25 subnational REDD+ project documents to assess the extent to which REDD+ project objectives align with Sustainable Development Goals (SDG) targets, and evaluates the reporting of progress towards meeting these objectives. Currently the CCB standards address a relatively small subset of SDG targets. Despite this, we find that REDD+ projects aspire to work on a much broader set of SDG target objectives, thus going beyond what the CCB Standards require for REDD+ validation. However, although reviewed REDD+ projects have these aspirations, very few are actively monitoring impact against the goals. There is a gap between aspiration and reported progress at the goal level, and for each project: on average, only a third of SDGs that are being targeted by REDD+ projects are showing ‘improvement’. The analysis shows which global goals are most frequently targeted, and which are the least. It also allows an analysis of which projects are following through most effectively in terms of monitoring progress towards the SDGs. This assessment provides insights into the priorities of REDD+ project proponents, suggesting that REDD+ has unfulfilled potential to elicit positive change in relation to the SDGs. Our analysis also shows that there is considerable potential for the safeguarding bodies to do more to ensure that real improvements are made, and reported against, aligning REDD+ projects more strongly with global development agendas.

Description: Many northern hardwood stands include several low-vigor trees as a result of past management. To restore these degraded stands, partial cuts are applied with partly validated tree classification systems that are based upon apparent stem defects. We sampled 214 sugar maple (Acer saccharum Marsh.) and 84 yellow birch (Betula alleghaniensis Britt.) trees from six sites covering the northern hardwood forest zone of the Province of Quebec, Canada. We evaluated their vigor with a four-class system, and quantified the growth efficiency index and several indices that were based solely upon radial growth. The growth efficiency index increased non-significantly with increasing tree vigor class. The five-year basal area increment (BAI-1-5) was significantly different between the lowest and highest tree vigor classes. Yet, temporal changes in BAI-1-5 helped classify correctly only 16% of high-vigor trees that became poorly vigorous 8–10 years later. Overall, these results suggest that the tree classification system is weakly related to actual tree vigor and its application likely generates few significant gains in future stand vigor. Modifying and simplifying the tree vigor system must be considered to facilitate the tree marking process that is required to improve the vigor of degraded stands.

Description: Despite strong expectations regarding the role that forestry, with its multitude of potential benefits, could and should play in the ‘bio-economy’, little research has been done on the actual perceptions of influential actors on how to best address future forest land-use disputes. We want to shed light on whether and in which contexts expectations regarding the bio-economy, e.g., the strong role of markets, are likely. The paper analyses influential actors’ core values and beliefs about the primary facilitators and the most appropriate instruments for resolving disputes over future forest land use. We used Social Network Analysis-based sampling and a quantitative semi-structured questionnaire, which included a preference analysis with twelve items covering broad issues and disputes related to future forest land use, to identify actors’ beliefs about and preferences for facilitators and policy instruments within key issues for future land use. The respondents were asked to identify one of five ‘primary facilitators’ (state, market, society, individual citizens/owners, leave it to nature) and distribute six points to a maximum of three preferred instruments (eight items, covering a broad set of instruments, from dictates or bans to awareness raising). The results are based on the perceptions of the influential or most important actors from various innovative government and private forest initiatives in Bavaria (Germany), Slovenia, Castilla y León (Spain), Nordeste (Portugal), and Latvia (481 actor responses, 109 initiatives). The initiatives included participatory mountain forest initiatives, forest intervention zones, afforestation projects, forest owner associations, and model forest and labelling initiatives. The results provide insight into the similarities and differences between European countries and actor groups regarding the preferred facilitators and instruments for solving future forest problems. In light of disagreement in the literature on the role of the state or markets in future forest land use and the bio-economy, our results show that the market and its instruments are considered to play a dominant role in wood mobilisation. With respect to all other issues (socio-ecological, societal, other), the state or other institutions and their instruments gain priority. The state is considered to play a stronger role in developing new markets, e.g., for energy transition or new uses of wood, contrary to liberal market expectations. Ecological and social problems are considered to be outside of the market domain. Here, the state is called in, e.g., to steer recreational issues, the provision of ecosystem services, or the improvement of the protective function. The clearest preference across all regions is for the state to secure the provision of ecosystem services, in contrast to calls for future markets to regulate this field.

Description: Carbon pool assessments in forests is one of the most important tasks of forest ecology. Despite the wide cultivation range, and economical and traditional importance, the aboveground biomass of European larch (Larix decidua Mill.) stands is poorly characterized. To increase knowledge about forest biomass accumulation and to provide a set of tools for aboveground biomass estimation, we studied a chronosequence of 12 larch forest stands (7–120 years old). From these stands, we measured the biomass of 96 sample trees ranging from 1.9 to 57.9 cm in diameter at breast height. We provided age-specific and generalized allometric equations, biomass conversion and expansion factors (BCEFs) and biomass models based on forest stand characteristics. Aboveground biomass of stands ranged from 4.46 (7-year-old forest stand) to 445.76 Mg ha−1 (106-year-old). Stand biomass increased with increasing stand age, basal area, mean diameter, height and total stem volume and decreased with increasing density. BCEFs of the aboveground biomass and stem were almost constant (mean BCEFs of 0.4688 and 0.3833 Mg m−3, respectively). Our generalized models at the tree and stand level had lower bias in predicting the biomass of the forest stands studied, than other published models. The set of tools provided fills the gap in biomass estimation caused by the low number of studies on larch biomass, which allows for better estimation of forest carbon pools.

Description: Internationally forest biomass is considered to be a valuable renewable energy feedstock. However, utilization of forest harvesting residues is challenging because they are highly varied, generally of low quality and usually widely distributed across timber harvesting sites. Factors related to the collection, processing and transport impose constraints on the economic viability of residue utilization operations and impact their supply from dispersed feedstock locations. To optimize decision-making about suitable locations for biomass energy plants intending to use forest residues, it is essential to factor in these supply chain considerations. This study conducted in Tasmania, Australia presents an investigation into the integration of Multi-criteria analysis (MCA) and Geographical Information systems (GIS) to identify optimal locations for prospective biomass power plants. The amount of forest harvesting biomass residues was estimated based on a non-industrial private native resource model in Tasmania (NIPNF). The integration of MCA and a GIS model, including a supply chain cost analysis, allowed the identification and analysis of optimal candidate locations that balanced economic, environmental, and social criteria within the biomass supply. The study results confirm that resource availability, land use and supply chain cost data can be integrated and mapped using GIS to facilitate the determination of different sustainable criteria weightings, and to ultimately generate optimal candidate locations for biomass energy plants. It is anticipated that this paper will make a contribution to current scientific knowledge by presenting innovative approaches for the sustainable utilization of forest harvest residues as a resource for the generation of bioenergy in Tasmania.

Description: Optimal planning of the amount and type of resources needed for extinguishing a forest fire is a task that has been addressed in the literature, using models obtained from operational research. In this study, a general integer linear programming model is proposed, which addresses the allocation of resources in different time periods during the planning period for extinguishing a fire, and with the goal of meeting Spanish regulations for the non-negligence of fronts and periods of rest for pilots and brigades. A computer program and interface were developed using the R language. By means of an example using historical data, we illustrate the model at work and its exact resolution. Then, we carry out a simulation study to analyze the obtained objective functions and resolution times. Our simulation study shows that an exact solution can be obtained very quickly without requiring heuristic algorithms, provided that the planning period does not exceed five hours.

Description: A variety of commercial instruments are available for sampling and quantifying microscopic airborne organisms from the environment. Although most samplers are highly sensitive, they are also expensive, costing thousands of dollars per unit, a price that is out of reach for many researchers, especially those looking to design experiments with replication. While looking at options to monitor pine stands for the presence of Fusarium circinatum, the causal agent of pitch canker disease, on multiple sites with several units per site, we developed a simple, low-cost spore trap that allows surveying spore abundance in outdoor environments. The trap consists of a rotating motor that holds a metal rod and two petroleum jelly-coated microscope slides. As the motor rotates, the slides collect airborne particles. To test whether the traps allowed detection of F. circinatum spores, we placed six traps on three sites: an actively-managed slash pine commercial stand located in Lake Butler, FL, a semi-managed loblolly and slash pine stand near Gainesville, FL, and a site with little perturbance at Goethe State Forest, FL, consisting of mainly slash pine trees. The slides were replaced weekly, and F. circinatum was detected by quantitative PCR using species-specific primers. Results show detection of low levels ( X ¯ = 1.7–77.1 picograms ± SE = 0.3–39.7) of the pathogen spores with high reproducibility. These traps offer a low-cost solution to spore, pollen, or small insect trapping experiments for initial or general assessment of a pathogen or species population. Their low cost has the added benefit that multiple traps can be deployed per experiment, thus increasing statistical power by using multiple replications.

Description: Close-to-nature urban forests and remnants of natural vegetation represent an important opportunity for urban residents to experience daily perception of and access to the natural environment. Despite there being a high percentage of forest cover (59%) and a favorable structure of the prevailing forested landscapes in Slovenia, urban expansion and infrastructure-driven development has severely weakened the connectivity and conservation of urban and suburban forests. The majority of urban settlements lie within walking distance of the surrounding forests (〈1 km). However, only close-to-nature forests with relatively low silvicultural inputs offer ecosystem services sufficient to fulfil the supply and demand of the expanding urban population. In order to estimate the conservation of forests in the open space of Slovenian settlements, we used a spatial model of landscape structure and forest connectivity. The model can be enhanced with patterns of corridors and stepping stones of natural vegetation in the landscape matrix to provide support in the decision-making process of landscape planning and the conservation of urban and suburban forests.

Description: Accurate forest above-ground biomass (AGB) is crucial for sustaining forest management and mitigating climate change to support REDD+ (reducing emissions from deforestation and forest degradation, plus the sustainable management of forests, and the conservation and enhancement of forest carbon stocks) processes. Recently launched Sentinel imagery offers a new opportunity for forest AGB mapping and monitoring. In this study, texture characteristics and backscatter coefficients of Sentinel-1, in addition to multispectral bands, vegetation indices, and biophysical variables of Sentinal-2, based on 56 measured AGB samples in the center of the Changbai Mountains, China, were used to develop biomass prediction models through geographically weighted regression (GWR) and machine learning (ML) algorithms, such as the artificial neural network (ANN), support vector machine for regression (SVR), and random forest (RF). The results showed that texture characteristics and vegetation biophysical variables were the most important predictors. SVR was the best method for predicting and mapping the patterns of AGB in the study site with limited samples, whose mean error, mean absolute error, root mean square error, and correlation coefficient were 4 × 10−3, 0.07, 0.08 Mg·ha−1, and 1, respectively. Predicted values of AGB from four models ranged from 11.80 to 324.12 Mg·ha−1, and those for broadleaved deciduous forests were the most accurate, while those for AGB above 160 Mg·ha−1 were the least accurate. The study demonstrated encouraging results in forest AGB mapping of the normal vegetated area using the freely accessible and high-resolution Sentinel imagery, based on ML techniques.

Description: The classification of discrete forest disturbance events is usually based on the spatial extent, magnitude, and frequency of the disturbance. Based on these characteristics, disturbances are placed into one of three broad categories, gap-scale, intermediate-severity, or catastrophic disturbance, along the disturbance classification gradient. We contend that our understanding of disturbance processes near the endpoints of the disturbance classification gradient far exceeds that of intermediate-severity events. We hypothesize that intermediate-severity disturbances are more common, and that they are more important drivers of forest ecosystem change than is commonly recognized. Here, we provide a review of intermediate-severity disturbances that includes proposed criteria for categorizing disturbances on the classification gradient. We propose that the canopy opening diameter to height ratio (D:H) be used to delineate gap-scale from intermediate-severity events and that the threshold between intermediate and catastrophic events be based on the influence of residual trees on the composition of the regeneration layer. We also provide examples of intermediate-severity disturbance agents, return intervals for these events, and recommendations for incorporating natural intermediate-severity disturbance patterns in silvicultural systems.

Description: The multiple agroforestry land uses of oak forests are of great ecological and economic interest as they contribute to the improvement of animal husbandry, wildlife, and environment. However, herbivory by wildlife and livestock highly affects the structure and the dynamic of forest ecosystems including its regeneration. The aim of this study was to investigate the comparative effect of wild boar and small ruminants herbivory on the regeneration of a deciduous oak forest in northern Greece. Eight sites were selected in an even aged stand of similar canopy cover and forest site quality: four sites with long-time use mainly by wild boar and four sites with long-time grazing by sheep and browsing by goats. A plot of 150 m2 in each of the sites was fenced in order to be protected from herbivory. The plant cover and number of oak seedlings and acorns was measured in both grazed and protected plots for four consecutive years. The plant cover increased in the protected plots independent of the type of animals. The seedling cover decreased about 29% and 9% in sites where small ruminants and wild boars foraged respectively. Similarly, the number and the weight of acorns significantly decreased in the sites grazed by small ruminants mainly during the mast year of the oaks. Forest management has to control the small ruminants grazing in terms of intensity, timing, and duration in order to ensure the sustainability of the ecosystem.

Description: Douglas-fir, the most important timber species in the Pacific Northwest, US (PNW), has high stiffness and strength. Growing it in plantations on short rotations since the 1980s has led to concerns about the impact of juvenile/mature wood proportion on wood properties. Lumber recovered from four sites in a thinning trial in the PNW was analyzed for relationships between thinning regime and lumber grade yield. Linear mixed-effects models were developed for understanding how rotation age and thinning affect the lumber grade yield. Log small-end diameter was overall the most important for describing the presence of an appearance grade, generally exhibiting an indirect relationship with the lower quality grades. Stand Quadratic Mean Diameter (QMD) was found to be the next most uniformly important predictor, its influence (positive or negative) depending on the lumber grade. For quantity within a grade, as log small-end diameter increased, the quantity of the highest grade increased, while decreasing the quantity of the lower grades differentially. Other tree and stand attributes were of varying importance among grades, including stand density, tree height, and stand slope, but logically depicted the tradeoffs or rebalancing among the grades as the tree and stand characteristics change. Structural lumber grade presence was described best by acoustic wave flight time, log position (decreasing presence in upper logs), and an increasing presence with rotation age. A smaller set of variables proved useful for describing quantity within a structural grade. Forest managers can use these results in planning to best capture value in harvesting, allowing them to direct raw materials (logs) to appropriate manufacturing facilities given market demand.