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  • Articles  (24,701)
  • Canadian Science Publishing  (14,226)
  • Cambridge University Press  (10,475)
  • Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition  (24,701)
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  • 1
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    Effect of protein level and grain source on milk production, nutrient digestibility and ruminal fermentation in primiparous Holstein cows (2021)
    Cambridge University Press
    Details
    Publication Date: 2021-02-26
    Description: This study investigated whether the interaction of protein level and grain type can affect milk production, nutrient digestibility and rumen fermentation in primiparous Holstein cows. Four dietary treatments were used: high-protein with barley as the only grain source, HP-B; (2) high-protein with an equal mix of barley and maize, HP-BM; (3) low-protein with barley as the only grain source, LP-B and (4) low-protein with equal proportions of barley and maize, LP-BM. High-protein diets showed no improvement in milk or protein yield compared with low-protein, but barley and maize mix diets increased energy-corrected milk yield and fat yield compared with barley-only diets. The highest total apparent digestibility of dry matter, organic matter and neutral detergent fibre was observed for LP-BM whereas HP-BM showed the greatest crude protein digestibility. Treatment had no effect on total volatile fatty acid concentrations, molar proportion of acetate and propionate and acetate to propionate ratio. The lowest ruminal pH was observed for LP-B. High-protein diets resulted in greater concentrations of ammonia nitrogen (N), urinary N, blood and milk urea nitrogen compared with low-protein diets, whereas low-protein diets showed better nitrogen utilization efficiency. This study showed that primiparous lactating cows do not benefit from high-protein diets with different fermentation rates of grain sources, but barley and maize diets may improve milk production performance, ruminal fermentation and pH under the present dietary conditions. The current results on milk production performance should be interpreted with caution due to the small number of cows used (eight in each treatment).
    Print ISSN: 0021-8596
    Electronic ISSN: 1469-5146
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Published by Cambridge University Press
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  • 2
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    Variation in PLIN2 and its association with milk traits and milk fat composition in dairy cows (2021)
    Cambridge University Press
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    Publication Date: 2021-03-30
    Description: The current study investigated associations between variation in the bovine perilipin-2 gene (PLIN2) and milk traits (milk fat content, milk protein content, milk yield and milk fatty acid (FA) component levels) in 409 New Zealand pasture-grazed Holstein-Friesian × Jersey-cross (HF × J-cross or Kiwicross™) cows. Five nucleotide sequence variants were found in three regions of the gene, including c.17C〉T in exon 2, c.53A〉G in exon 3, c.595+23G〉A and c.595+104_595+108del in intron 5, and c.*302T〉C in the 3′-untranslated region. The c.*302T〉C substitution produces two nucleotide sequence variants (A5 and B5), and this variation was associated with variation in milk protein content and milkfat composition for C10:0, C11:0, C12:0, C13:0 and C16:0 FA and medium-chain fatty acid (MCFA) and long-chain fatty acid (LCFA) groups. After correcting for the effect of variation in the diacylglycerol acyl-CoA acyltransferase 1 gene (DGAT1) that results in the amino acid substitution p.K232A, variation in the FA binding protein 4 gene (FABP4) and variation in the stearoyl-CoA desaturase (Δ-9-desaturase) gene (SCD) that results in the amino acids substitution p.A293V, significant differences between A5A5 and B5B5 cows were found for C10:0, C11:0, C12:0, C13:0, C16:0, and the MCFA, LCFA, total saturated FA and C10:1 index groups. This suggests that nucleotide sequence variation in PLIN2 may be affecting milk FA component levels.
    Print ISSN: 0021-8596
    Electronic ISSN: 1469-5146
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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  • 3
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    Nitrogen and phosphorus distribution in plant, soil and leachate as affected by liquid hog manure and chemical fertilizers (2021)
    Canadian Science Publishing
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    Publication Date: 2021-03-22
    Description: A two-year field study was conducted on a coarse textured soil in Manitoba, Canada, to investigate the effects of liquid hog manure (LHM) and chemical fertilizer application on barley (2005) and red spring wheat (2006) yields, crop nutrient uptake and nitrogen (N) and phosphorus (P) movement to the environment. The treatments were LHM applied at two rates as 22000 L ha-1 (2500 gal ac-1, abbreviated as M2500) and 43000 L ha-1 (5000 gal ac-1, abbreviated as M5000) and two rates of chemical fertilizer to match total N and P in LHM treatments, F2500 and F5000, along with an unamended control. The M5000 and M2500 treatments showed similar grain yield and N and P uptake. However, M5000 and M2500 significantly increased grain yield by 67% and 78%, respectively, compared to the control in 2005. In 2006, wheat grain yields from M2500 and M5000 were 71% and 86% greater than the control. In 2005, leachate NO3-N concentrations and leaching loads were higher with chemical fertilizers than M2500. In 2005, the apparent recovery of applied N as leachate was 35% and 23% in F5000 and F2500 treatments, whereas it was 6% and 7% of applied N in M5000 and M2500 plots, respectively. However, the application of M5000 resulted in P accumulation near the surface and may increase the potential risk of P loss with runoff. Our results show that applying LHM at moderate rates (M2500) may ensure desirable crop yields comparable to higher rates of nutrient application with minimal potential losses relative to higher rates.
    Print ISSN: 0008-4271
    Electronic ISSN: 1918-1841
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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  • 4
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    Is the annual maximum leaf area index an important driver of water fluxes simulated by a land surface model in temperate forests? (2021)
    Canadian Science Publishing
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    Publication Date: 2021-03-24
    Description: In land surface models, vegetation is often described using plant functional types (PFTs), a classification that aggregates plant species into a few groups based on similar characteristics. Within-PFT variability of these characteristics can introduce considerable uncertainty in the simulation of water fluxes in forests. Our objectives were to (i) compare the variability of the annual maximum leaf area index (LAImax) within and between PFTs and (ii) assess whether this variability leads to significant differences in simulated water fluxes at a regional scale. We classified our study region in southwestern Quebec (Canada) into three PFTs (evergreen needleleaf, deciduous broadleaf, and mixed forests) and characterized LAImax using remotely sensed MODIS-LAI data. We simulated water fluxes with the Canadian Land Surface Scheme (CLASS) and performed a sensitivity analysis. We found that within-PFT variability of LAImax was 1.7 times more important than variability between PFTs, with similar mean values for the two dominant PFTs, deciduous broadleaf forests (6.6 m2·m−2) and mixed forests (6.3 m2·m−2). In CLASS, varying LAImax within the observed range of values (4.0–7.5 m2·m−2) led to changes of less than 2% in mean evapotranspiration. Overall, LAImax is likely not an important driver of the spatial variability of water fluxes at the regional level.
    Print ISSN: 0045-5067
    Electronic ISSN: 1208-6037
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Published by Canadian Science Publishing
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  • 5
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    Influence of Continuous Application of Feedlot Manure and Legacy Treatments on Soil Organic Carbon, Soil Hydrophobicity, and Soil Water Repellency (2021)
    Canadian Science Publishing
    Details
    Publication Date: 2021-03-22
    Description: Continuous or discontinued manure applications to agricultural soils may impact soil organic carbon (SOC) and water balances because of manure carbon inputs and the potential for manure-induced soil hydrophobicity (SH) and soil water repellency (SWR). A laboratory study was conducted using a long-term (44 yr) field experiment on a clay loam soil to determine the effect of application rate of feedlot manure under dryland (0, 30, 60, and 120 Mg ha-1 wet wt.) and irrigation (0, 60, 120, 180 Mg ha-1) on SOC, SH and SWR. In addition, we compared the effect of 44 yr of continuous annual manure applications (C44) to legacy treatments which had discontinued applications for 14 yr (D14) or 30 yr (D30). Laboratory measurements were conducted on air-dried and sieved ( 1.95) SWR. Manure application rate had a significant (P ≤ 0.05) and positive effect on SOC and SH, and both followed an exponential model. In contrast, RI had a negative response to application rate under dryland and had no response under irrigation. Overall, positive responses of SOC and SH to application rate supported our hypothesis, but it was not supported for RI. The hypothesis of greater SOC, SH, and RI for continuous versus discontinued treatments was also supported for SOC and SH, but not for RI.
    Print ISSN: 0008-4271
    Electronic ISSN: 1918-1841
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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  • 6
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    Improvement of root morphological characteristics on water percolation rate in grassland soils of Yellow River riparian buffer strips (2021)
    Canadian Science Publishing
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    Publication Date: 2021-03-22
    Description: Soil water percolation is an important process required to meet plant water needs, determine soil water storage, and affect soil water quality in riparian buffer strips. However, the effects of plant roots on soil percolation in riparian buffer strips are not totally understood, and contradictory results have been carried out on the effects of the root system on soil percolation rates. This study aimed to investigate soil percolation in natural grasslands and evaluate the relationships between root morphological characteristics and percolation rates. Path analysis was used to provide information on the relative contribution of root characteristics on soil percolation rates. Three mixed grasslands (Imperata cylindrica + Phragmites australis, Imperata cylindrica + Cynodon dactylon, Imperata cylindrica + Juncellus serotinus) were selected in the Yellow River wetland natural reserves of Zhengzhou. Soil percolation rates (initial, average and steady infiltration rates) were measured by using double-ring methods, and plant root morphological characteristics were analyzed. Soil percolation rates and plant root characteristics parameters of Imperata cylindrica + Phragmites australis and Imperata cylindrica + Cynodon dactylon were higher than those of Imperata cylindrica + Juncellus serotinus. Initial percolation rate of Imperata cylindrica + Phragmites australis and Imperata cylindrica + Cynodon dactylon at 0-10cm depth was 58.06% and 95.55% higher than that of Imperata cylindrica + Juncellus serotinus, respectively. Percolation rates had a significant positive correlation with root characteristic parameters, and the main factor controlling soil percolation rates was root volume density. Mixed natural grasslands with more root volume density improved soil infiltration and percolation rates.
    Print ISSN: 0008-4271
    Electronic ISSN: 1918-1841
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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  • 7
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    Reducing peat in growing media: impact on N content, microbial activity and CO2 and N2O emissions (2021)
    Canadian Science Publishing
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    Publication Date: 2021-03-10
    Description: Renewable materials including coir, biochar and composts are investigated worldwide in the horticultural industry to partially substitute peat in growing media. In this study, we assessed the effects of biochar and vermicompost as partial substitution of peat, and compared these peat-based growing media with coir in terms of NH4+-N and NO3--N content, CO2-C and N2O-N emissions and their microbial biomass carbon (MBC) and nitrogen (MBN). Six growing media mixtures (peat; peat+biochar 9:1 v/v; peat+vermicompost 9:1 v/v; coir; coir+biochar 9:1 v/v; coir+vermicompost 9:1 v/v) replicated three times were incubated in growth chambers during a 60-days period. At day 0 of incubation (DAI), peat amended with biochar retained around 12.81% of NH4+-N compared with peat alone. The concentrations of NO3--N peaked at 275 mg kg–1 at 33 DAI for peat and 552 mg kg–1 at 46 DAI for coir amended with vermicompost. The substitution of peat with biochar resulted in large CO2-C (2070 µg CO2-C g–1 dry weight (dw)) and N2O-N (62.78 µg N2O-N g–1 dw) emissions, but not coir. The substitution of coir with vermicompost increased N2O-N emissions at a much lower level (47.53 µg N2O-N g–1 dw) than peat (111.82 µg N2O-N g–1 dw). Our results showed that supplements of vermicompost in peat and coir improved N supply which could benefit plant growth, while substituting part of peat with biochar increased CO2-C and N2O-N emissions. In contrast, no effect of biochar was observed with coir, which is beneficial for the environmental footprint of short-cycle growing crops.
    Print ISSN: 0008-4271
    Electronic ISSN: 1918-1841
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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  • 8
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    A new generation of sensors and monitoring tools to support climate-smart forestry practices (2021)
    Canadian Science Publishing
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    Publication Date: 2021-03-16
    Description: Climate-smart forestry (CSF) is an emerging branch of sustainable adaptive forest management aimed at enhancing the potential of forests to adapt to and mitigate climate change. It relies on much higher data requirements than traditional forestry. These data requirements can be met by new devices that support continuous, in-situ monitoring of forest conditions in real time. We propose a comprehensive network of sensors, i.e. a wireless sensor network (WSN), that can be part of a world-wide network of interconnected uniquely addressable objects, an Internet of Things (IoT), which can make data available in near real time to multiple stakeholders, including scientists, foresters, and forest managers, and may partially motivate citizens to participate in big data collection. The use of in-situ sources of monitoring data as ground-truthed training data for remotely sensed data can boost forest monitoring by increasing the spatial and temporal scale of the monitoring, leading to a better understanding of forest processes and potential threats. Here, some of the key developments and applications of these sensors are outlined, together with guidelines for data management. Examples are given of their deployment to detect early warning signals (EWS) of ecosystem regime-shifts in terms of forest productivity, health and biodiversity. Analysis of the strategic use of these tools highlights the opportunities for engaging citizens and forest managers in this new generation of forest monitoring.
    Print ISSN: 0045-5067
    Electronic ISSN: 1208-6037
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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  • 9
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    Effects of ionized brackish water and polyacrylamide application on infiltration characteristics and improving water retention and reducing soil salinity (2021)
    Canadian Science Publishing
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    Publication Date: 2021-02-17
    Description: There is an urgent need for brackish groundwater-based irrigation methods to be developed for saline soils that are effective, economically advantageous, and environmentally friendly. The use of both ionized brackish water and polyacrylamide (PAM) might provide such a method. The long-term use of brackish water irrigation can lead to the secondary salinization of soil and, as a consequence, restrict the development of the agricultural economy. Here, we conducted one-dimensional vertical infiltration experiments to examine the effects of ionized brackish water and PAM on soil infiltration characteristics. The result indicated that the water retention of soil first increased and then decreased with the increased in PAM application rates. The maximum water retention of soil was obtained in PAM application of 0.04% for ionized brackish water treatment. Soil water storage for the 0.04% PAM application under ionized brackish water irrigation was the highest and 5.1% higher compared with non-ionized brackish water at a PAM application rate of 0.04%. The ionized brackish water treatment at a PAM application rate of 0.04% improved the desalinization efficiency by 2.3% compared with non-ionized brackish water treatment. Thus, ionized treatment and PAM application are effective for improving the characteristics of soil water and salt transport and permit the safe use of brackish groundwater for irrigation.
    Print ISSN: 0008-4271
    Electronic ISSN: 1918-1841
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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  • 10
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    Soil organic carbon storage by shaded and unshaded coffee systems and its implications for climate change mitigation in China (2021)
    Cambridge University Press
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    Publication Date: 2021-02-17
    Description: Shaded coffee systems can mitigate climate change by fixation of atmospheric carbon dioxide (CO2) in soil. Understanding soil organic carbon (SOC) storage and the factors influencing SOC in coffee plantations are necessary for the development of sound land management practices to prevent land degradation and minimize SOC losses. This study was conducted in the main coffee-growing regions of Yunnan; SOC concentrations and storage of shaded and unshaded coffee systems were assessed in the top 40 cm of soil. Relationships between SOC concentration and factors affecting SOC were analysed using multiple linear regression based on the forward and backward stepwise regression method. Factors analysed were soil bulk density (Ïb), soil pH, total nitrogen of soil (N), mean annual temperature (MAT), mean annual moisture (MAM), mean annual precipitation (MAP) and elevations (E). Akaike's information criterion (AIC), coefficient of determination (R2), root mean square error (RMSE) and residual sum of squares (RSS) were used to describe the accuracy of multiple linear regression models. Results showed that mean SOC concentration and storage decreased significantly with depth under unshaded coffee systems. Mean SOC concentration and storage were higher in shaded than unshaded coffee systems at 20–40 cm depth. The correlations between SOC concentration and Ïb, pH and N were significant. Evidence from the multiple linear regression model showed that soil bulk density (Ïb), soil pH, total nitrogen of soil (N) and climatic variables had the greatest impact on soil carbon storage in the coffee system.
    Print ISSN: 0021-8596
    Electronic ISSN: 1469-5146
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Published by Cambridge University Press
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  • 11
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    Stand density management diagrams: modelling approaches, variants, and exemplification of their potential utility in crop planning (2021)
    Canadian Science Publishing
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    Publication Date: 2021-02-01
    Description: The evolving shift in forest management objectives towards the collective consideration of volumetric yield, end-product quality and value, and ecosystem service outcomes, while accounting for the impacts of anthropogenic climate change, has resulted in innovative advancements in decision-support models used in stand density management. This review provides a synopsis of these efforts with respect to static, dynamic, and structural stand density management diagrams (SDMDs). More precisely, the scope of this review includes an ecology-based perspective of stand density management, summarization of the foundational quantitative relationships along with their utilization within the analytical structure of the SDMD, examination of SDMD compliance with underlying ecological constructs and empirical prediction expectations, exemplification of a climate-sensitive structural SDMD variant in boreal crop planning, and identification of outstanding analytical challenges and plausible future research directions for advancing the SDMD modelling approach and its utility in stand-level management planning. Collectively, this account of the conceptual basis, historical analytical evolution, ecological integrity, predictive ability, application diversity, and demonstrated utility of the various SDMD variants solidifies the prerequisite evidentiary foundation for the continued development and deployment of SDMD-based crop planning decision-support models.
    Print ISSN: 0045-5067
    Electronic ISSN: 1208-6037
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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  • 12
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    Predicting soil nitrogen availability to grain corn in Ontario, Canada (2021)
    Canadian Science Publishing
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    Publication Date: 2021-03-10
    Description: Predicting the soil available nitrogen (N) to grain corn over a growing season in humid temperate regions is the key for improving fertilizer N recommendations. The objective of this study was to evaluate a suite of soil-N tests to predict soil N availability to grain corn over two growing seasons at 13 individual sites with long-term history of synthetic N fertilization in Ontario, Canada (13 site-years). At each site, fertilizer N was applied at various rates (0-224 kg N ha-1) to determine the crop response to N fertilizer, relative yield (RY) and the most economic rate of N (MERN). Across the entire dataset, water-extractable mineral N (WEMN) was the only soil test that strongly correlated to both RY (r = 0.74**) and MERN (r = -0.56*) indicating that in grain corn fields with long-term history of N fertilization, mineral forms of N in soil solution can be used for fertilizer N recommendations in southern and eastern Ontario. We also provide evidence that grouping soils based on clay content could further refine fertilizer-N recommendations for grain corn in Ontario. A multi-year validation of the WEMN test with more field sites and development of a fertilizer recommendation table for this soil test are recommended.
    Print ISSN: 0008-4271
    Electronic ISSN: 1918-1841
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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  • 13
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    Evaluation of a combination of phosphorylated fibers and zeolite as a potential substitute to synthetic wetting agents in peat moss products (2021)
    Canadian Science Publishing
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    Publication Date: 2021-02-17
    Description: Water availability and pH are important factors to consider to determine the suitability of a material for use as a growing medium. Unfortunately, most horticultural substrates are characterized by their water repellency. This is the case with peat moss which is hydrophobic and acidic. Synthetic surfactants are required to improve its wettability. In this study, a combination of phosphorylated wood pulp fibers (FLP) and zeolite is proposed as a substitute to surfactants to increase the wettability of peat moss in the presence of lime, an additive generally used as fertilizer or pH regulator. Results show that lime reduces the water retention capacity of FLP. However, the addition of 15% zeolite to the peat moss/FLP system increases the pH and water retention of the substrate. The negative effect of the presence of 1 wt. % lime on the water retention of the peat moss/FLP mixture was corrected by zeolite addition. Optimal conditions were obtained at 10% zeolite for the two types of lime tested with favorable pH and water retention capacity values. Zeolite was shown to have a higher affinity than FLP for calcium ions preventing the detrimental interaction between FLP and calcium ions.
    Print ISSN: 0008-4271
    Electronic ISSN: 1918-1841
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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  • 14
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    Phosphorus saturation index and water-extractable phosphorus in high-legacy phosphorus soils in southern British Columbia, Canada (2021)
    Canadian Science Publishing
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    Publication Date: 2021-03-03
    Description: Understanding of the risk of phosphorus (P) loss to the environment is crucial to monitor soil P and implement policies for P management. We assessed P sorption characteristics and adapted a P saturation index (PSI) for silage corn and blueberry fields in south coastal British Columbia (BC), Canada. We used 284 composite soil samples with contrasting P levels collected from eight silage corn and 23 blueberry fields across south coastal BC. The P sorption maximum (Smax) varied between 982 and 2532 mg P·kg−1 and was influenced by aluminum concentration and organic matter content. The degree of P saturation was related to water-extractable P (Pw) by a quadratic regression with R2 = 0.85. A critical Pw = 3.7 mg·kg−1 was established across the two cropping systems. The silage corn fields with pH 〉 5.5 had critical PSI value of 10.4%, and blueberry fields with pH 
    Print ISSN: 0008-4271
    Electronic ISSN: 1918-1841
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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  • 15
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    OBITUARY – Professor Theresa (Terry) A. S. Aveling (2021)
    Cambridge University Press
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    Publication Date: 2021-03-09
    Print ISSN: 0021-8596
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    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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  • 16
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    Quantifying the vertical diversification development stage of old-growth Douglas-fir to derive stage-specific targets for restoration silviculture (2021)
    Canadian Science Publishing
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    Publication Date: 2021-03-01
    Description: Structural variability in natural Douglas-fir (Pseudotsuga menziesii (Mirbel) Franco) forests hinders restoration targets for the full old-growth developmental sequence. To guide stage-specific restoration, we present a new approach toward developing a simple index of the vertical diversification (VD) stage. VD-associated sub-stand structures were objectively identified by quantifying the size structures of live trees across a developmental sequence of 10 pristine stands in the Oregon Cascades, USA. Floating neighborhoods were used to delineate natural tree neighborhoods based on triangulated irregular networks in five concentric rings of ever-greater spatial extent (averaging 60–2060 m2). Diameter distributions summarized the most frequently encountered tree size structures among neighborhoods, with increasing deviation from the neutral multi-variate core. Of 18 observed diameter distribution types (DDTs), the core DDT characterized all-sized tree neighborhoods reflective of vertical diversification, which was most abundant in early old-growth (VD) stands and least abundant at the extremes of the sequence. VD declined in older stands, whose more distinct DDTs had peaks in larger trees and multiple size classes, likely reflecting horizontal diversification (HD). This new approach illustrates that structural restoration of VD stands could be facilitated by the single-tree selection method, while that of HD stands may be promoted with both single-tree and group selection as well as targeted release.
    Print ISSN: 0045-5067
    Electronic ISSN: 1208-6037
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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  • 17
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    Functional soil organic matter fractions in response to long-term fertilizer management in a double-cropping paddy field of southern China (2021)
    Cambridge University Press
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    Publication Date: 2021-03-12
    Description: Soil organic matter (SOM) and its fractions play an important role in maintaining or improving soil quality and soil fertility. Therefore, the effects of a 34-year long-term fertilizer regime on six functional SOM fractions under a double-cropping rice paddy field of southern China were studied in the current paper. The field experiment included four different fertilizer treatments: chemical fertilizer alone (MF), rice straw residue and chemical fertilizer (RF), 30% organic manure and 70% chemical fertilizer (OM) and without fertilizer input as control (CK). The results showed that coarse unprotected particulate organic matter (cPOM), biochemically, physically–biochemically and chemically protected silt-sized fractions (NH-dSilt, NH-μSilt and H-dSilt) were the main carbon (C) storage fractions under long-term fertilization conditions, accounting for 16.7–26.5, 31.1–35.6, 16.2–17.3 and 7.5–8.2% of the total soil organic carbon (SOC) content in paddy soil, respectively. Compared with control, OM treatment increased the SOC content in the cPOM, fine unprotected POM fraction, pure physically protected fraction and physico-chemically protected fractions by 58.9, 106.7, 117.6 and 28.3%, respectively. The largest proportion of SOC to total SOC in the different fractions was biochemically protected, followed by chemically and unprotected, and physically protected were the smallest. These results suggested that a physical protection mechanism plays an important role in stabilizing C of paddy soil. In summary, the results showed that higher functional SOM fractions and physical protection mechanism play an important role in SOM cycling in terms of C sequestration under the double-cropping rice paddy field.
    Print ISSN: 0021-8596
    Electronic ISSN: 1469-5146
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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  • 18
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    Soybean and soil responses to biochar amendment in controlled environments with elevated temperature and carbon dioxide (2021)
    Canadian Science Publishing
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    Publication Date: 2021-03-03
    Description: Warmer atmospheric temperatures (eT) will increase plant nutrient uptake, and elevated atmospheric CO2 (eCO2) is expected to enhance plant growth, whereas a multicomponent eTeCO2 effect should also be beneficial for agroecosystems. Our goal was to understand if single- (eT, eCO2) or multicomponent (eTeCO2) climate effects, predicted for southern Ontario, Canada, will affect soybean and soil properties differently when soil is amended with manure and biochar (MB) or with manure, nitrogen (N) fertilizer, and biochar (MNB) compared with the addition of manure and N fertilizer (MN). We hypothesized that biochar regulates climate effects and causes soybean and soil properties to be similar to ambient climate conditions than soil without biochar. However, soil amended with biochar functioned independently of single- or multicomponent climate effects. Soybean pod and shoot biomass, shoot height, and shoot:root ratio were greater (p 
    Print ISSN: 0008-4271
    Electronic ISSN: 1918-1841
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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    Mineralization of bagged pruning waste in agrosystem on the subtropical coast of Andalusia (Spain) (2021)
    Cambridge University Press
    Details
    Publication Date: 2021-03-18
    Description: Spreading of pruning waste over the soil surface may increase soil organic carbon, thus improving soil physical properties and serving as a source of nutrients and energy for microbial populations. The aim of this study was to test the effect of the environmental conditions and the biochemical composition of pruning waste from avocado, cherimoya, mango and gardens on their decomposition process in a Mediterranean subtropical climate. Bagged pruning and garden waste were placed on the ground at a distance of 1 m around the trunk of the three trees from each crop. The concentrations in C, N, lignin, cellulose, hemicellulose, other extracts and ash were determined at the beginning of the experiment (T0), after six (T6) and 24 (T24) months in the field. Initially, significant differences were detected for all types of waste, especially in lignin, hemicellulose, cellulose and other extracts. No significant differences were found in the N content and the C content in mango pruning waste was significantly lower than that in avocado. The greatest weight loss recorded at T24 (63.2%) was related to the lower content in lignin, cellulose and other extracts. Weight losses and C concentrations showed negative correlations with lignin content. Despite the intense decomposition of all the waste, between 55 and 36.8% of the original weights were recorded at the end of the experiment. Recalcitrant C could be the result of the lignin concentrating in the case of the garden waste applied to the different crops.
    Print ISSN: 0021-8596
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    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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    Wood density variation in naturally regenerated stands of Pinus ponderosa in northern Arizona, USA (2021)
    Canadian Science Publishing
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    Publication Date: 2021-03-22
    Description: In the southwestern United States, land managers are implementing large-scale forest restoration projects involving treatments designed to improve forest health, protect ecosystem services, and reduce the risk of catastrophic wildfire in overstocked ponderosa pine (Pinus ponderosa Dougl. ex P. & C. Laws.) forests. A better understanding of wood properties is necessary to improve the currently limited markets for the woody byproducts generated by these treatments. Therefore, our objective was to investigate variations in ponderosa pine wood density across the northern Arizona landscape. We sampled trees from 18 naturally regenerated stands and used X-ray densitometry to quantify the radial and axial variation within and among trees. We modeled within-stem wood density patterns using generalized additive models, and investigated the effects of climatic variation using response function analyses. Additionally, we tested the effects of site-level predictors on whole-tree wood density. We found high variability in radial wood density profiles among trees in our stands compared with that observed in studies of other species grown in plantations — perhaps due to high genetic variation within naturally regenerated stands. Wood density was negatively correlated with precipitation at annual and most quarterly intervals, except for a positive correlation with late-summer monsoon precipitation. The high wood density variation we found among trees highlights the need for further investigation of controls over wood properties in natural nonplantation forests.
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    Cattle manure loadings and legacy effects on Cu and Zn availability under rainfed and irrigated conditions (2021)
    Canadian Science Publishing
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    Publication Date: 2021-02-03
    Description: Long term cattle manure applications build up nutrient pools and can lead to trace element enrichments in soils. The objectives of this study were to evaluate Cu and Zn loadings in the soil during continuous annual cattle manure applications and determine the time required for soil to return to its pre-manure available Cu and Zn levels after manure is discontinued. The manure application rates were 0, 30, 60, and 90 Mg ha-1 for rainfed and 0, 60, 120, and 180 Mg ha-1 (wet weight) for irrigated plots. While manure was applied for 45 years in some plots, applications were terminated in one subset of treatments after 14 years and in another subset after 30 years to study legacy effects after 31 and 15 years, respectively. Soil samples were collected in the fall of 2003, 2008, 2013, and 2018 and analyzed for available Cu and Zn. Crops were grown in all years continuously with Cu and Zn concentrations measured in both silage and grains harvested. The regression model developed using data collected suggests long legacy effects with recovery time to pre-manure levels ranging from 10-20 years for Cu and 23-41 years for Zn at irrigated and 10-24 for Cu and 21-32 years for Zn under rainfed, respectively. Long term applications of cattle manure could lead to accumulation of Cu and Zn, creating long-lasting legacy effects in soils with the increased environmental risk of leaching to groundwater
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    Effect of temperature on microbial residue dynamics in a temperate farmland soil (2021)
    Canadian Science Publishing
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    Publication Date: 2021-02-03
    Description: Microorganisms mediate soil organic carbon (SOC) turnover, and microbial residues contribute a significant portion to SOC storage in temperate agroecosystems. However, little is known about the direct effect of temperature on microbial residues associated with SOC sequestration/decomposition. We assessed microbial residue dynamics in a 28 d incubation conducted at four temperatures (5, 15, 25, and 35 °C). Microbial residues did not change with time from 5 to 25 °C. However, at 35 °C, fungal residues decomposed significantly with time, and the decomposition rate was higher than SOC. Considering the important contribution of fungal residues to stable-C pool, our findings indicated warming may be detrimental to C stability in this temperate soil.
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    Seeds of change? Seed transfer governance in British Columbia: insights from history (2021)
    Canadian Science Publishing
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    Publication Date: 2021-02-01
    Description: Tree seed transfer is critical to effective reforestation programs, and exploring its policy roots provides insights to understand future, and potentially controversial, actions like assisted migration. We offer a historical overview of seed transfer governance in British Columbia, Canada, by applying analytics from the policy change and knowledge co-production literatures. Based on document analysis and semi-structured interviews with key informants, we trace governance attributes to examine how and why policies have changed (or not) over time. We reveal a paradigmatic shift in seed transfer governance, culminating in a climate-based seed transfer system — informed largely by genetic knowledge — that emerged through a policy window opening. In contrast, governance processes remained relatively unchanged in practice, including the disproportionately influential role of the forest industry in policy-making. These insights shed light on the legacies of a government–industry policy coalition that influence underlying seed transfer objectives (i.e., forest productivity), and help to explain the ongoing dominance of particular knowledge forms used to inform policy. We highlight the need for increased contributions from a wider range of expertise, stakeholders, and rights holders in developing seed transfer policies for future forests.
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    Effects of warming and oxalic acid addition on plant–microbial competition in Picea brachytyla (2021)
    Canadian Science Publishing
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    Publication Date: 2021-02-16
    Description: The importance of oxalic acid for tree seedling growth and the competition for inorganic nitrogen (N) by plants and soil microorganisms under warming was investigated using 15N tracer techniques in Picea brachytyla (Franch.) E. Pritz. Results showed that warming combined with oxalic acid application induced growth enhancements in seedlings primarily through increases in fine root length and fine root surface area. Moreover, soil NH4 +, NO3 –, PO4 3–, N mineralization, microbial biomass carbon (MBC), and microbial biomass nitrogen (MBN) were significantly higher or tended to be higher with oxalic acid application. However, warming with oxalic acid application altered the partitioning of N between plants and soil microorganisms by increasing microbial 15N recovery to a lesser extent than it increased plant 15N recovery. While plants showed no specific preferences between N forms under normal conditions or warming alone, under warming and oxalic acid, plants showed a preference for 15NO3. Microorganisms showed a stronger preference for 15NH4 especially under warming and oxalic acid treatments. These findings suggest that plasticity in resource use could be an important mechanism in alleviating competition for soil N between plants and microbes under warming and oxalic acid addition.
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    Nitrogen fertilizer value of animal slurries with different proportions of liquid and solid fractions: A 3-year study under field conditions (2021)
    Cambridge University Press
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    Publication Date: 2021-02-23
    Description: The plant availability of manure nitrogen (N) is influenced by manure composition in the year of application whereas some studies indicate that the legacy effect in following years is independent of the composition. The plant availability of N in pig and cattle slurries with variable contents of particulate matter was determined in a 3-year field study. We separated cattle and a pig slurry into liquid and solid fractions by centrifugation. Slurry mixtures with varying proportions of solid and liquid fraction were applied to a loamy sand soil at similar NH4+-N rates in the first year. Yields and N offtake of spring barley and undersown perennial ryegrass were compared to plots receiving mineral N fertilizer. The first year N fertilizer replacement value (NFRV) of total N in slurry mixtures decreased with increasing proportion of solid fraction. The second and third season NFRV averaged 6.5% and 3.8% of total N, respectively, for cattle slurries, and 18% and 7.5% for pig slurries and was not related to the proportion of solid fraction. The estimated net N mineralization of residual organic N increased nearly linearly with growing degree days (GDD) with a rate of 0.0058%/GDD for cattle and 0.0116%/GDD for pig slurries at 2000–5000 GDD after application. In conclusion NFRV of slurry decreased with increasing proportion of solid fraction in the first year. In the second year, NFRV of pig slurry N was significantly higher than that of cattle slurry N and unaffected by proportion between solid and liquid fraction.
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    Wheat straw and biochar effect on soil carbon fractions, enzyme activities, and nutrients in a tobacco field (2021)
    Canadian Science Publishing
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    Publication Date: 2021-02-18
    Description: Annual removal of tobacco residues and insufficient input of organic materials have exacerbated total organic carbon (TOC) depletion and soil degradation in a tobacco field in the Huanghuai area. Straw residue and biochar application may be effective ways to increase TOC accumulation and improve soil fertility. In this field experiment, wheat straw (WS) and wheat-straw derived biochar (BC) with mineral fertilizer were compared to mineral fertilizer alone (CK) and we assessed their effects on soil organic carbon fractions, enzyme activities, and nutrients in Shandong Province, China during 2016 and 2017. At 0–20 cm depth, the WS treatment had a greater overall effect on the measured soil properties. Compared with the control, the WS treatment significantly increased the concentrations of microbial biomass carbon (MBC), hot water-extractable carbon (HWC), and permanganate-oxidizable carbon concentrations (POXC; by 252.41%, 107.02%, and 65.53%, respectively); the activities of sucrase, urease, and phosphatase (by 112.52%, 7.81%, and 34.33%, respectively); and the contents of alkaline hydrolysable nitrogen, available phosphorus, and available potassium (by 92.22%, 100.78%, and 10.57%, respectively). Compared with the control, the BC treatment significantly increased TOC content, MBC content, light fraction organic carbon (LFOC) and potassium (TK) concentration (by 74.93%, 86.24%, 153.73%, and 21.92%, respectively). Most soil enzyme activity and nutrient parameters were significantly correlated with MBC. Thus, straw application improved soil fertility by increasing the concentrations of high labile organic carbon fractions (HWC, MBC, POXC), stimulating soil enzyme activities, and releasing more soil available nutrients, and BC addition contributed to the accumulation of TOC, MBC, LFOC, and TK.
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    Fall-applied cattle manure did not provide nitrogen fertilizer value to spring cereal crops (2021)
    Canadian Science Publishing
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    Publication Date: 2021-02-03
    Description: Fall-applied manure may have nitrogen (N) fertilizer value for spring-seeded crops. We applied liquid or solid cattle manure to plots on a sandy-loam soil in southern Quebec in fall. The following spring, half of each plot received urea fertilizer before planting the spring cereal crop. Total N content of the spring cereal at tillering, flowering, and maturity was lower in subplots without urea, and yields were up to 183% less in the no-urea subplots, regardless of whether liquid or solid manure was applied in fall. Fall-applied manure did not provide plant-available N to spring cereals under our growing conditions.
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    Soil Mehlich-3 extractable elements as affected by the addition of biochars to a clay soil co-amended with or without a compost (2021)
    Canadian Science Publishing
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    Publication Date: 2021-04-16
    Description: Biochar has potential to sequester carbon and mitigate greenhouse gas emissions, and it may also contribute nutrients for plant growth in temperate climates. Nutrient availability in biochar-amended soil was assessed in a 338-d incubation study. The clay soil prepared with 4% w/w (dry basis) compost or without compost, then amended with wood-based biochar made at different pyrolysis temperatures (maple bark [Acer saccharum] at 400°C [M400], 550°C [M550] and 700°C [M700]) on a dry-rate basis of 5% (w/w). After moistening the soil mixture to 44% volumetric soil water content (equivalent to 70% water-filled pore space), soil mixtures were incubated in the dark at 22°C. Soil was sampled at days 9, 16, 23, 44, 86, 23 170 and 338 of the incubation. Biochar amendment increased the Mehlich-3 P, K, Ca, Mg and Cu concentrations, and reduced the Mehlich-3 Al and Fe concentrations at each sampling date, and M400 had the most significant effect on Mehlich-3 extractable nutrient concentrations. Compost addition also increased the amounts of extractable nutrients. These results suggested that M400 and carbon-rich compost promoted microbial growth and mineralization in amended soil. In addition, soil mixed with compost and amended with biochar had more Mehlich-3 extractable K than when compost or biochar were applied alone, probably due to greater growth and activity of soil K-solubilizing microorganisms. Overall, our study indicated that co-application of wood-based biochar and compost could improve soil fertility in temperate regions by increasing the availability of most plant macronutrients and micronutrients.
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    Evaluation and modeling of factors influencing the depth of mixing layer in which soil solute releasing from soil to surface runoff (2021)
    Canadian Science Publishing
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    Publication Date: 2021-04-19
    Description: The depth of mixing layer is one of the important parameters which cannot be assigned a constant value affected by many factors in the slope runoff. The objective of this study was to investigate the effect of slope length and underground biomass on slope runoff, solute transport processes, as well as mixing layer depth. In this study, the experimental plots with the four slope lengths (5, 10, 15, and 20 m) and a width of 2 m were built on the slope with the gradient of 20°. In addition, the plots with the millet or wheat planting were built on the slope. The change of runoff and solute transport was analyzed through simulated rainfall experiments and then to estimate mixing layer depth. The results showed that the runoff rate decreased and more runoff seeped into the slope soil with increasing slope length. Increasing underground biomass also promoted greater rainfall infiltration into the soil. The increase in slope length increased the concentration of solute in runoff, but more underground biomass reduced the nutrients transported with runoff. The effective mixing depth increased with an increase in slope length, but effective mixing depth decreased with increased underground biomass. The modified expression of the equivalent mixing model under different slope lengths and underground biomass could accurately describe the solute transfer process in runoff when compared with complete mixing model and incomplete mixing model based on exponential functions. This research provided a reference for improving the application of mixing layer models in the slope management.
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    Understanding soil fertility status in Newfoundland from standard farm soil tests (2021)
    Canadian Science Publishing
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    Publication Date: 2021-04-14
    Description: Farm soil tests are common decision support tools employed by regulatory agencies and farmers to manage nutrients in an economical and environmentally sustainable way. The complex interplay between the local environment and locally relevant crops makes soil testing, and critically soil-test based recommendations, site-specific. Newfoundland and Labrador (NL) has a relatively small but rapidly growing commercial agriculture, mainly on lands converted from the boreal forest over the last 80 years. A first step towards developing locally calibrated fertilizer recommendations is understanding current practices. For this, we examined regular farm soil test reports and associated recommendations for Newfoundland (Nfld). Following a request distributed to 167 farmers, 1503 soil tests were obtained from 32 farms. While tests exemplify the gamut of crops in Nfld, more than half were from forage and mixed forage fields in western Nfld, representing dairy farms. Results show that even in the absence of more comprehensive site analyses, an investigative survey of farm tests may be employed to recognize possible environmental and economic inefficiencies of local cropping systems, including regional and crop type-driven differences, for both nitrogen (N) and phosphorus (P) fertilization. Soil-test based identification of possible N and/or P inefficiencies and associated crop and regional particularities, including excess fertilization, can be employed to devise targeted research for improved, preventative decision tools to increase the sustainability of Nfld agricultural systems.
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    SPATIAL DEPENDENCY OF SOIL CHEMICAL IN PRODUCTION SYSTEMS IN THE ANTHROPOGENIC DARK EARTH (2021)
    Canadian Science Publishing
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    Publication Date: 2021-04-15
    Description: Anthrosols refers to anthropic soils of high fertility in general, but the concentration of these nutrients may vary according to the occupation of indigenous people in the past or due to current soil use. This study aimed to evaluate the spatial variability of the chemical attributes of the soil in areas of guandu bean production and pasture and to compare with natural forest systems on Anthropogenic dark earth (ADE). For this assessment, 88 sampling points were selected in the area with natural forest vegetation and pasture and 90 sampling points in an area of guandu bean production. Soil samples were collected from layers 0.00-0.05, 0.05-0.10 and 0.10-0.20 m. Chemical analyses of the soil were conducted to determine organic matter, pH, Aluminium (Al3+), soil acidity (H+Al), phosphorus (P), potassium (K+), Calcium (Ca2+), Magnesium (Mg2+), cation exchange capacity (CEC), sum of bases (SB) and base saturation (V%). Data were analyzed using descriptive statistics and geostatistics to sample range, sample density was estimated for each attribute. Guandu bean showed high content of soil organic matter in relation to pasture in the superficial layer (0.00-0.05 m). Based on sample density, lower variability and higher spatial continuity were observed for guandu bean in relation to pasture and natural forest in the layers of 0.00-0.05 and 0.05-0.10 m. It was found that the use and continuous management of ADE’s areas alter the content and distribution of soil fertility and in some cases may even improve chemical attributes when compared to areas not used with agricultural crops.
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    Wood-based biochar for small fruit production in southern Quebec, Canada (2021)
    Canadian Science Publishing
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    Publication Date: 2021-04-15
    Description: The market for small fruits (grapes, blueberries, strawberries, and raspberries) is valued at more than CAD100 million per year in Quebec, Canada. Wood-based biochar is an amendment that improves soil quality, which may boost small fruit growth and production. The objective of this research was to determine if wood-based biochar could increase the yield and quality of grape, blueberry, strawberry, and raspberry in southern Quebec. We evaluated the fruit yield as well as the quality parameters like average fruit weight, fruit firmness, color, juice pH, total soluble solids, total phenolic content, and antioxidant activity. Field trials were established on commercial farms with grape, blueberry, strawberry, and raspberry production systems in plots that received wood-based biochar and no biochar in spring (April to May). Small fruits were harvested at their ripening stage for yield and quality evaluation in fall (July to October). Biochar application did not improve yield and quality parameters of small fruits except it gave a marginal higher yield of grape (3.7 vs. 4.4 t ha-1, P = 0.08) and a higher average fruit weight of strawberry (11.9 vs. 13.2 g, P 〈 0.05). There was no difference in the quality of the fruit from biochar-amended and control plots in the first year of biochar application, possibly because the quality parameters are affected more by weather conditions, handling, and storage than by soil quality. This work suggests that wood-based biochar (
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    Nano-oxides immobilize Cd, Pb, and Zn in mine spoils and contaminated soils facilitating plant growth (2021)
    Canadian Science Publishing
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    Publication Date: 2021-04-26
    Description: Nanoparticles with high reactivity can be applied as amendments to remediate soil metal contaminations by immobilizing toxic elements. Nano-oxides of Fe have been studied but Al and Ti nano-oxides have not been tested for their remediation capacity of toxic metals. The potential of synthesized iron (Fe-O), aluminum (Al-O), and titanium (Ti-O) nano-oxides for stabilizing Cd, Pb, and Zn in mine spoil (Chat) and contaminated soil was compared using adsorption studies and a greenhouse experiment. Chat and soil were amended with nano oxides at two rates (25 and 50 g kg-1) and a pot experiment was conducted with sorghum (Sorghum bicolor L. Moench). Leachates were collected twice per week from plant emergence to harvest at maturity and metals were compared against an unamended control. Chat was contaminated with Cd, Pb, and Zn at 84, 1583, and 6154 mg kg-1, and soil at 15, 1260, and 3082 mg kg-1, respectively. Adsorption conformed to the Langmuir linear isotherm and adsorption maxima of metals were in the order of Al-O 〉 Ti-O ≥ Fe-O. Nano-oxides reduced Cd concentration by 28% (Fe-O) to 87% (Ti-O) and Zn concentration by 14% (Fe-O) to 85% (Al-O) in plant tissues compared with unamended Chat. Nano-oxides significantly reduced Cd, Pb, and Zn in leachates and available Cd and Zn in Chat/ soil relative to the respective unamended controls. Nano-oxides can be used to remediate heavy metal contaminated Chat and soil and facilitate plant growth under proper nutrient supplements. Nano-oxides of Al-O and Ti-O remediated metals more effectively than Fe-O
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    Recycled Nutrients Supply Phosphorus and Improve Ryegrass Yields on Phosphorus Depleted Soil (2021)
    Canadian Science Publishing
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    Publication Date: 2021-04-26
    Description: Recycling phosphorus (P) within the food system is fundamental to long-term sustainability. This greenhouse study compared three sources of recycled P – struvite precipitated from municipal wastewater, black soldier fly frass from food waste, and anaerobic digestate of food waste – to mono-ammonium phosphate (MAP), compost, and a control. Italian Ryegrass (Lolium multiflorum) was harvested four times during a 123 day trial from a P-depleted soil. In nitrogen (N) sufficient conditions, all amendments significantly increased cumulative ryegrass yields compared to the control, and were not significantly different from MAP. Relative P supply was frass=MAP〉struvite〉= compost〉=digestate〉〉control. The recycled nutrient sources tested show promise as sustainable P sources.
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    Productivity of coastal Douglas-fir and western redcedar in response to species mixture, planting density, and soil carbon:nitrogen ratio (2021)
    Canadian Science Publishing
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    Publication Date: 2021-04-27
    Description: Mixed-species plantations have been suggested as ecologically and economically viable alternatives to monocultures. We examined the growth response of coastal Douglas-fir (Pseudotsuga menziesii var. menziesii (Mirb.) Franco) and western redcedar (Thuja plicata Donn ex D. Don in Lamb.) to different species mixtures (Douglas-fir : western redcedar mixtures of 1:0, 1:1, 1:3, and 0:1) and planting densities (500, 1000, and 1500 stems·ha−1) in a dry maritime forest on eastern Vancouver Island, Canada. Twenty-two years postplanting, species mixture significantly affected diameter and height growth (p 〈 0.001), with stand diameter and height generally decreasing with increasing redcedar composition. Inherent variation in soil productivity across the plantation (carbon:nitrogen ratio) equally constrained stand growth. The widest spacing had larger diameter than the closest spacing (p = 0.025) but the least stand basal area compared with the other spacing treatments (p = 0.003–0.031). Stand volume was significantly affected by mixture × density interaction (p = 0.024) and generally declined with increasing proportion of redcedar and decreasing stand density. In the first decades after plantation establishment, inherent species growth traits and soil fertility were most important in dictating stand productivity. Because of the differences in resource utilization of both species, stand dynamics may change as competition for light and soil resources increases. Evaluation of silvicultural recommendations regarding mixtures of both species will continue with plantation development.
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    Note of appreciation / Note de reconnaissance (2021)
    Canadian Science Publishing
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    Publication Date: 2021-03-01
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    Effects of different barley grain preservation techniques on intake, growth and carcase traits of finishing dairy bulls fed grass silage-based rations (2021)
    Cambridge University Press
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    Publication Date: 2021-02-10
    Description: The effects of different barley grain preservation techniques on intake, growth and carcase traits of dairy bulls were determined in a feeding trial using 52 Holstein and 48 Nordic Red bulls which were allotted to four feeding treatments (five pens and 25 bulls per treatment). Spring barley was harvested with a conventional combine harvester and four different preservation techniques formed the four experimental treatments. Dry grain (DG) was dried to the targeted dry matter (DM) concentration of 870–880 g/kg and rolled within 7 days prior to feeding. High moisture grain treated with a formic acid-based additive (FA) was harvested and crimped on the targeted DM content of 700 g/kg. Low moisture grain treated with a urea-based additive (UR) and low moisture grain treated with a propionic acid-based additive (PA) were harvested and crimped on the targeted DM content of 800 g/kg. The bulls were fed with total mixed ration ad libitum. On DM basis, the diets included grass silage (500 g/kg), barley grain (485 g/kg) and a mineral–vitamin mixture (15 g/kg). Daily DM intake (DMI) and live weight gain were 6% higher when crimped grains were used instead of DG (P 〈 0.05). There were no observed significant differences in DMI, gain or carcase traits between high moisture and low moisture crimped grain treatments or between UR and PA. The current results show that producers have the option to vary grain preservation system without major changes to growth performance or carcase traits.
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    A new empirical equation to describe the vertical leaf distribution profile of maize (2021)
    Cambridge University Press
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    Publication Date: 2021-02-10
    Description: The characteristic traits of maize (Zea mays L.) leaves affect light interception and photosynthesis. Measurement or estimation of individual leaf area has been described using discontinuous equations or bell-shaped functions. However, new maize hybrids show different canopy architecture, such as leaf angle in modern maize which is more upright and ear leaf and adjacent leaves which are longer than older hybrids. The original equations and their parameters, which have been used for older maize hybrids and grown at low plant densities, will not accurately represent modern hybrids. Therefore, the aim of this paper was to develop a new empirical equation that captures vertical leaf distribution. To characterize the vertical leaf profile, we conducted a field experiment in Jilin province, Northeast China from 2015 to 2018. Our new equation for the vertical distribution of leaf profile describes leaf length, width or leaf area as a function of leaf rank, using parameters for the maximum value for leaf length, width or area, the leaf rank at which the maximum value is obtained, and the width of the curve. It thus involves one parameter less than the previously used equations. By analysing the characteristics of this new equation, we identified four key leaf ranks (4, 8, 14 and 20) for which leaf parameter values need to be quantified in order to have a good estimation of leaf length, width and area. Together, the method of leaf area estimation proposed here adds versatility for use in modern maize hybrids and simplifies the field measurements by using the four key leaf ranks to estimate vertical leaf distribution in maize canopy instead of all leaf ranks.
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    Fifty years of forest science (2021)
    Canadian Science Publishing
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    Publication Date: 2021-02-01
    Print ISSN: 0045-5067
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    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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    In situ techniques to predict in vivo digestibility and to evaluate the impact of flint maize processing methods on degradation parameters (2021)
    Cambridge University Press
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    Publication Date: 2021-02-08
    Description: This study aimed to (1) evaluate the effects of flint maize processing methods on the estimation of the readily soluble fraction (a), the potentially degradable fraction (b) and the rate of degradation of b (c) for dry matter (DM), organic matter (OM) and starch in the rumen; and (2) verify whether two different applications of in situ technique can be used to estimate in vivo DM, OM and starch digestibilities. Five ruminally cannulated Nellore bulls (265 ± 18.2 kg; 8 ± 1.0 mo) were distributed in a 5 × 5 Latin square. Three experimental diets were composed of 0.30 whole-plant maize silage, 0.10 supplement and 0.60 of one of the following processing methods: dry ground maize grain (DMG); high-moisture maize (HMM); reconstituted maize grain silage (RMG). Two additional diets were composed of 0.10 supplement, 0.80 snaplage and 0.10 stalklage (SNAP-80); or 0.10 supplement and 0.90 snaplage (SNAP-90). Digestibilities were estimated using in vivo procedure or predicted from in situ technique using a single 24 h incubation point or an equation proposed in previous literature. Diets based on ensiled grains presented greater (P 〈 0.05) fraction a and c and lower (P 〈 0.05) fraction b of DM, OM and starch compared to DMG. Both alternative use of in situ technique accurately estimated (P 〉 0.05) in vivo DM, OM and starch digestibilities. The results suggest that ensilage process may increase the availability of nutrients. The two different applications of in situ technique showed precision and accuracy to estimate in vivo digestibility.
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    Estimating rill erosion and sediment transport processes along a saturated purple soil slope (2021)
    Canadian Science Publishing
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    Publication Date: 2021-04-14
    Description: A plough pan with reduced permeability always accumulates infiltrated water along slopes then saturates the cultivated layer under continuous rain. Topsoil saturation is a frequent phenomenon and an important process of the special soil slopes. A methodology and device system was used in this study to keep cultivated purple soil saturated. Strands of scouring tests were developed to quantify the rill erosion and sediment transport processes along a saturated purple soil slope at four experiment slopes (5°, 10°, 15°, and 20°) and three flow discharges (2, 4 and 8 L min−1). The experimental results indicated that the sediment transport capacity on a saturated purple soil slope ranged from 0.03 to 1.56 kg s−1 m−1 with the increasing trend along the slope gradient and flow discharge, and the increasing trend could be well matched by a nonlinear multivariable equation. The sediment concentration of the saturated purple soil slope exponentially increased with rill length and decreased with the increment rate and the maximum sediment concentrations observed in this study in different hydraulic events ranged from 108.13 to 1174.20 kg m-3. Saturated and non-saturated purple soil slopes erode differently with the maximum sediment concentration of saturated purple soil slope recorded at approximately 1.42-2.10 times the values for non-saturated purple soil slope. The findings of this research help illustrate the sediment transportation and erosion behaviors of a saturated purple soil slope, and serve as the basis for determining the parameters in the erosion models of the purple soil slope.
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    Effects of mulching with crushed wheat straw padding and plastic film on sunflower emergence, yield, and yield components under different irrigation intensity in the northwest arid regions, China (2021)
    Canadian Science Publishing
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    Publication Date: 2021-04-08
    Description: Crops in the northwest arid region of China frequently suffer from low emergence and poor yield due to high water deficit. Mulching is an important approach to reduce irrigation amount while increasing productivity but faces challenge of ecological adaptability in this region. A field experiment was carried out in the three growing seasons from 2011 to 2013 to study effects of mulching with crushed wheat straw padding and plastic film on sunflower seed emergence and yields under different irrigation intensities. A two factor (mulching, irrigation intensity) completely randomized block design was applied, resulting in a total of 12 treatments repeated three times. Mulching treatments includes: zero mulch (N), straw mulching at the beginning of trial (S), plastic film mulching when sowing (F), a commonly used mulching by local farmers, and double mulching with plastic film on the crushed wheat straw layer (SF). Irrigation intensity includes: High (H=900 m3 ha-1), Medium (M=750m3 ha-1), Low (L=600m3 ha-1). Results showed that all mulching treatments promoted early emergence of seedlings compared with N, with SF and F performing the better than the rest. SF was the best-performing mulching approach in this study, and had significantly improved sunflower yield and yield components compared with other treatments. In SF, medium irrigation level had significantly increased sunflower 100-seed weight. Therefore, SF with medium irrigation level showed the most positive effect on sunflower production and in now the recommended agronomic solution for sunflower production in the northwest arid regions and potentially, other irrigated areas with similar ecological conditions.
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    Root physiological responses can explain the effects of short-term plant-plant interactions on growth of two subalpine coniferous species (2021)
    Canadian Science Publishing
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    Publication Date: 2021-04-13
    Description: Root functional traits play an important role in nutrient acquisition of plants, affecting the outcome of plant-plant interactions. However, few studies have comprehensively investigated the plastic responses of plant root traits to plant-plant interactions. A pot experiment was conducted to quantify the effects of intraspecific and interspecific interactions on seedlings growth and multiple root traits of two coniferous species, Picea asperata and Abies faxoniana. The results showed that plant-plant interactions changed root physiology of two species but did not affect their root system, morphological, architectural and biotic traits. Intraspecific interaction resulted in lower root N content and stronger resource competition than under interspecific interaction. Under intraspecific interaction, P. asperata had lower root vigor and nitrate reductase activity, which impeded the acquisition and utilization of the limited resources, and thus resulted in marginally decreased total biomass; while total biomass for A. faxoniana was not significantly affected. Under interspecific interaction, the high total biomass of A. faxoniana could be explained by rhizosphere interactive effects and reduced metabolic (carbon and nitrogen) costs due to lower root exudative outputs. Our results demonstrate that root physiological responses can explain the effects of short-term plant-plant interactions on plant growth.
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    LEAF LITTER DYNAMICS IN WESTERN BLACK SEA MOUNTAINOUS FOREST ECOSYSTEMS (2021)
    Canadian Science Publishing
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    Publication Date: 2021-04-13
    Description: This study aimed to estimate leaf litter decomposition rates in eastern beech (Fagus orientalis Lipsky) and sweet chestnut (Castanea sativa Mill.) mixed stands in Düzce-Akçakoca, located in the Western Black Sea Region of Turkey. The sampling areas represent four different elevations and two aspects at each elevation. Amounts of annual beech and chestnut litter fall were estimated as 5.19 Mg ha-1 and 4.61 Mg ha-1, respectively. Litter decomposition was examined over five time periods (0.25, 0.50, 1.25, 2.25, and 4.25 years) by using the litter bag method. The amount of remaining beech leaf litter mass was found to be 1.1, 1.2, 1.2, 1.4, and 1.3 times greater than the amount of chestnut leaf litter, respectively. However, estimated values for the decomposition rate-constant (k) of chestnut for all time periods were found to be approximately 1.5 times greater than those of beech leaf litter. Litter in beech stands decomposed more rapidly at higher elevations during the first year, but at lower elevations in the second year, likely due to increased temperature and precipitation for the corresponding years. Leaf litter in chestnut stands decomposed more rapidly at lower elevations in the second and fourth year, reflecting higher precipitation of those years.
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    Oat genotypic requirement for intercropping with vetch under Mediterranean conditions (2021)
    Cambridge University Press
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    Publication Date: 2021-02-24
    Description: Oat (Avena spp. L.) intercropped with common vetch (Vicia sativa L.) has shown high forage yield and crude protein content (CP) in rainfed Mediterranean environments of Greece. The objective was to study the oat genotypic interactions for yield, quality and agronomic traits of four oat accessions (cv. Flega and lines B2, B3 and B4) grown as intercrops with a common vetch cultivar (Pegasus) and as monocrops without or with nitrogen (N) supplementation (100 kg N/ha). In all mixtures, the land equivalent ratio exceeded the unit indicating that there was a yield advantage. Intercrops produced, on average, 5.0% less dry matter (DM) and 38.9% more crude protein yield (CPY) compared to monocropped oats with N fertilization and 3.4% more DM and 75.5% more CPY compared to monocropped oats without N fertilization. The DM, CP and quality differences between the intercropped and monocropped oats were attributed to oats by vetch cultivar interactions. The oat B2 intercropped was the shortest, the latest flowering and the less vigorous early in the season, a trait that allowed common vetch to dominate in the intercrop (vetch participation 770 g/kg). The high vetch fragment in the intercrop contributed to high CP, CPY, acid detergent lignin, total digestible nutrients, relative feeding value, relative forage quality, net energy for lactation and to low neutral detergent fibre, acid detergent fibre and hemicellulose. The replacement value index indicated that the intercrop was 21% more economically viable in comparison to the fertilized monocrop.
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    Climate-based Allometric Biomass Equations for Five Major Canadian Timber Species (2021)
    Canadian Science Publishing
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    Publication Date: 2021-04-20
    Description: Accurate estimation of forest biomass is essential to quantify the role forests play at balancing terrestrial carbon. Allometric equations based on tree size have been used for this purpose worldwide. There is little quantitative understanding on how environmental variation may affect tree allometries. Even less known is how to incorporate environmental factors into such equations to improve estimation. Here we tested the effects of climate on tree allometric equations and proposed to model forest biomass by explicitly incorporating climatic factors. Among the five major Canadian timber species tested, the incorporation of climate was not found to improve the allometric models. For trembling aspen and tamarack, the residuals of their conventional allometric models were found strongly related to frost-free period and mean annual temperature, respectively. The predictions of the two best climate-based models were significantly improved, which indicate that trembling aspen and tamarack store more aboveground biomass when growing in warmer than in colder regions. We showed that, under the RCP4.5 modest climate change scenario, there would be a 10% underestimation of aboveground biomass for these two species if the conventional non-climate models would still be in use in 2030. This study suggests the necessity to proactively develop climate-based allometric equations for more accurate and reliable forest biomass estimation.
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    Comprehensive yield gap analysis and optimizing agronomy practices of soybean in Iran (2021)
    Cambridge University Press
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    Publication Date: 2021-04-05
    Description: Soybean is one of the key oil crops in global food security. The objective of the current study was to determine the magnitude of soybean yield and yield gaps (Yg) in the main producing regions in Iran, the main causes and possible solutions to reduce these gaps and improve yields. This study uses an integrated approach of crop simulation and on-farm information. The SSM-iCrop2 model was used to calculate the potential yield (Yp). Furthermore, management information of soybean farms (the number of monitored farms was 224) was collected and analysed with two methods, including stepwise regression (a production model was created and based on it, the yield-limiting factors were determined) and boundary line analysis (show the optimum level of crop management and simultaneously the percentage of farms that were out of the optimal range of a specific management procedure). The results showed a Yp of 4681 kg/ha while actual yield (Ya) was around 2257 kg/ha. The main factors causing Yg of soybean in Iran were irrigation, nitrogen fertilizer, phosphorus fertilizer and sowing date. Altering soybean sowing date to late June or early July, irrigating at least five times during the growing season, applying at least 50 kg/ha nitrogen and 45 kg/ha phosphorus base application are foremost management practices that could shrink the soybean yield gap in Iran. The results presented in this study can bring relevant transferable information to other soybean production areas sharing the same latitudes and climate, and the approach can be used for other crops worldwide.
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    Evaluating irrigated rice yields in Japan within the Climate Zonation Scheme of the Global Yield Gap Atlas (2021)
    Cambridge University Press
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    Publication Date: 2021-04-05
    Description: The Global Yield Gap Atlas (GYGA) is an international project that addresses global food production capacity in the form of yield gaps (Yg). The GYGA project is unique in employing its original Climate Zonation Scheme (CZS) composed of three indexed factors, i.e. Growing Degree Days (GDD) related to temperature, Aridity Index (AI) related to available water and Temperature Seasonality (TS) related to annual temperature range, creating 300 Climate Zones (CZs) theoretically across the globe. In the present study, the GYGA CZs were identified for Japan on a municipality basis and analysis of variance (ANOVA) was performed on irrigated rice yield data sets, equating to actual yields (Ya) in the GYGA context, from long-term government statistics. The ANOVA was conducted for the data sets over two decades between 1994 and 2016 by assigning the GDD score of 6 levels and the TS score of 2 levels as fixed factors. Significant interactions with respect to Ya were observed between GDD score and TS score for 13 years out of 21 years implying the existence of favourable combinations of the GDD score and the TS score for rice cultivation. The implication was also supported by the observation with Yg. The lower values of coefficient of variance obtained from the CZs characterized by medium GDD scores indicated the stability over time of rice yields in these areas. These findings suggest a possibility that the GYGA-CZS can be recognized as a tool suitable to identify favourable CZs for growing crops.
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    Goats fed with non-protein nitrogen: ruminal bacterial community and ruminal fermentation, intake, digestibility and nitrogen balance (2021)
    Cambridge University Press
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    Publication Date: 2021-04-05
    Description: The current study assessed ruminal fermentation parameters and bacterial community, nutrient intake, nutrient digestibility and nitrogen balance of goats fed diets containing buffel grass hay and ruminal ammonia nitrogen (N-NH3). Five rumen-cannulated mixed-breed castrated adult goats (45 ± 2.3 kg) were used in a 5 × 5 Latin square design represented by five N-NH3 levels (3.43, 9.95, 17.2, 23.0 and 33.7 mg/dl). Control animals were fed hay exclusively. Other treatments were represented by ruminal infusion composed of a mixture containing urea, ammonium sulphate and casein. The increasing N-NH3 concentrations did not affect rumen fluid pH, which averaged 6.43. Rumen ammoniacal nitrogen increased linearly in response to N-NH3. Volatile fatty acids were not affected by increasing N-NH3 concentrations. A higher abundance of Ruminococcaceae (Ruminococcus 1, Ruminococcaceae UCG-014 and Ruminococcaceae NK4A214 group) was observed in the rumen of goats infused with higher concentrations of N-NH3 (17.2 and 33.7 mg/dl N-NH3). There was a quadratic effect (P 〈 0.050) of N-NH3 levels on neutral detergent fibre intake with maximum values estimated at 13.7 mg/dl N-NH3. Nutrient intake, nitrogen excretion and nitrogen balance presented a positive linear effect (P 〈 0.050). In conclusion, 3.43 mg/dl of N-NH3 is the minimum level to maintain microbial activity, whereas the recommended level to optimize the microbial community is 14.5 mg/dl of N-NH3 in the rumen of goats fed buffel grass.
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    Combining perennial grass–legume forages and liquid dairy manure contributes to nitrogen accumulation in a clayey soil (2021)
    Canadian Science Publishing
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    Publication Date: 2021-03-04
    Description: Repeated applications of liquid dairy manure (LDM) and perennial crops generally favor nitrogen (N) stocks in soils, but in ways that may differ with soil type and other management practices. The objective of this study was to assess the long-term (21 yr) changes in soil N stocks (0–50 cm) of a silty clay soil, in a cool humid climate, in response to mineral fertilization (MIN) or LDM, combined with two tillage practices [chisel plow (CP), or moldboard plow (MP)], and two crop rotations [cereal monoculture (monoculture) or cereal–perennial forage rotation (forage-based rotation)]. The forage-based rotation favoured a greater accumulation of N in the first 20 cm of soil (+50 kg N·ha−1·yr−1) when compared with the monoculture. Tillage practices did not impact N stocks in the whole soil profile, but influenced its vertical distribution, with greater accumulation at the surface with CP, and at depth with MP. Annual input of LDM increased N stocks at the surface (0–20 cm) compared with MIN, especially when combined with the forage-based rotation. After 21 yr, soil N stocks (0–50 cm) with LDM were 32% (+2 t N·ha−1) higher in the forage-based rotation than in the monoculture, suggesting better retention and more efficient use of manure-N with perennial forages than cereals. Comparisons between the N mass balance computed for each cropping system, and the changes in soil N stocks indicated that accumulation of N under the forage-based rotation was largely due to symbiotic fixation by legumes in the forage mixture.
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    Conflicting portrayals of remaining old growth: the British Columbia case (2021)
    Canadian Science Publishing
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    Publication Date: 2021-04-05
    Description: Old growth is disappearing globally with implications for biodiversity, forest resilience and carbon storage; yet uncertainty remains about how much exists, partly because assessments stratify ecosystems differently, sometimes obscuring relevant patterns. This paper compares portrayals of BC’s old growth forest stratified in two ways: by biogeoclimatic variant, as per policy, and by relative site productivity. Our analyses confirm provincial government claims that about a quarter of BC’s forests are old growth, but find that most of this area has low realized productivity, including subalpine and bog forests, and that less than 1% is highly productive old growth, growing large trees. Within biogeoclimatic variant, nearly half of high productivity forest landscapes have less than 1% of the expected area of old forest. Low productivity ecosystems are over-represented in protected forest. We suggest that the experiment of managing old growth solely by biogeoclimatic variant has failed, and that current forest policy, in combination with timber harvesting priorities, does not maintain representative ecosystems, counter to the intent of both policy and international conventions. Stratifying old growth by relative productivity within biogeoclimatic variant seems an appropriate method to portray ecosystem representation, potentially increasing the probability of maintaining ecosystem resilience.
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    “Prescribed fire shrub consumption in a Sierra Nevada mixed-conifer forest (2021)
    Canadian Science Publishing
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    Publication Date: 2021-04-13
    Description: Live shrubs in forest understories pose a challenge for mitigating wildfire risk with prescribed fire. Factors driving shrub consumption in prescribed fires are variable and difficult to explain. This study investigated spatial patterns and drivers of Sierra Nevada mixed-conifer forest shrub consumption in prescribed fires through analysis of high-resolution imagery taken before and after prescribed fire. We applied a spatially explicit, generalized additive model to assess tree cover and coarse woody material as potential drivers of shrub consumption. Shrub cover in two experimental stands prior to burning was 38% and 59% and was 36% and 45% one-year post burn. In both stands shrub patch density increased, while area-weighted mean patch size and largest patch index decreased. Increased local percent cover of coarse woody material was associated with increased shrub consumption. These findings provide information for prescribed fire managers to help better anticipate shrub consumption and patchiness outcomes under similar conditions.
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    Effects of induced water deficit and biofertilization on growth dynamics and bulb yield of onion (Allium cepa L.) in a neotropical semi-arid environment (2021)
    Canadian Science Publishing
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    Publication Date: 2021-04-08
    Description: In a scenario of world population increase and climate change, an efficient use of water is key for agricultural production. Onion is one of the most profitable crops and can adapt to particular conditions of water stress. The objective of this research was to determine growing degree-days (GDD) and accumulated radiation under non-stress conditions, and yield of an F1 2000 hybrid of onion (Allium cepa L.) under water deficit and biofertilization in a semi-arid environment. An established nutrient requirement of 247 kg N, 240 kg P2O5 (105 kg P), 240 kg K2O (199 kg K) and two irrigation factors were applied: normal irrigation (NI) with a daily and water deficit (WD) with a three-day interval irrigation frequencies. The effect of biofertilization was evaluated through the inoculation of a microbial consortium in combination with four NPK fertilizer treatments. The crop accumulated 1334 °Cd and 1188 MJ m-2 d-1 at the time of harvest at 71 days after transplanting (DAT). The yield was 36 t ha-1, similar under both irrigation conditions; and the WD treatment resulted in a 35% water savings, a 47% and 65% increase in water use efficiency (WUE) and modulus of elasticity, respectively. The microbial consortium resulted in a 50% NPK savings under non-limiting water conditions and produced a similar yield compared to the 100% NPK non-inoculated control. The lower irrigation frequency together with the 100% NPK fertilization dose without the microbial consortium, and the use of the microorganisms and the 50% NPK treatment without water stress are recommended as agrosustainable practices for onion production.
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    Accumulation of straw derived carbon, and changes in soil humic acid structural characteristics during corn straw decomposition (2021)
    Canadian Science Publishing
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    Publication Date: 2021-04-08
    Description: Appropriate application of corn straw residues increase soil organic carbon (SOC) sequestration. Yet, sequestration and stabilization of added carbon (C) during corn straw transformation is not fully understood. Here, we present changes in soil humus C and humic acid (HA) molecular structure during corn straw decomposition in an incubation experiment carried out for 270 days at 25 °C. Corn straw was applied at the amount of 74.76 g per 18 kg soil (i.e., 1.57 g C kg-1), in the soil surface (CS1), incorporated within 0–10 cm (CS2), applied below 10 cm soil depth (CS3), and no corn straw applied. The results showed that after corn straw application (CS1, CS2 and CS3), accumulation of SOC content was rapid in the first 90 days. The HA spectral results of straw amended soils showed a slight increase in aliphatic C compounds and amino acids in day 90. In day 180, the degree of condensation was less, and aliphatic C compounds were present in large quantities in soil HA. As decomposition advanced to day 270, the aliphatic character of HA appeared to slightly weaken, and soil HA was enriched with aromatic structures. These results suggest that corn straw application enrich soil HA with more aliphatic C compounds in the early stages of decomposition, and aromatic C structures are formed in the later stage of decomposition. Incorporation of corn straw into the soil (CS2 treatment) is more conducive in increasing SOC and aliphaticity in HA during corn straw decomposition, which can potentially increase C sequestration.
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    Fertilizing with composted cattle manure to meet agro-environmental targets in continuous corn and corn-soybean agroecosystems in southern Quebec (2021)
    Canadian Science Publishing
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    Publication Date: 2021-04-08
    Description: Balancing nutrient inputs from manure and supplemental inorganic fertilizers with crop requirements should achieve crop yield goals and agro-environmental targets. We asked if composted dairy cattle manure, alone or in combination with inorganic fertilizers, could sustain the corn and soybean yields, without increasing the residual soil N and soil P saturation of a sandy-loam soil in southern Quebec, Canada. Cropping systems were continuous silage corn and corn-soybean rotation, with each phase of the rotation grown every year, for 5-yr. Cropping systems were amended with compost at rates of 0, 15, 30 and 45 Mg (wet weight) ha-1, and received supplemental inorganic fertilizer to supply 200 kg N ha-1 yr-1 to corn while assuring that corn and soybean received 45 kg P ha-1 yr-1 and 125 kg K ha-1 yr-1 from compost and inorganic fertilizer. Crop yields were similar in composted-amended and inorganically-fertilized plots. Corn yield was limited by N availability, and there was no P or K limitation in corn and soybean. Soil P saturation in the 0–15 cm layer exceeded the agro-environmental limit of 13.1% P/Al for a sandy-loam soil in Quebec, indicating that the P input exceeded crop uptake. Residual soil N concentration was affected more by the crop than the fertilizer source, with greater residual soil N in plots with higher grain production. Crop-induced priming can explain how N fertilizer cycles through the soil microbial community and is gradually mineralized during the growing season, and why crop senescence may trigger residual soil N release after harvest.
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    MICROBIAL SOIL BIODIVERSITY IN BEECH FORESTS OF EUROPEAN MOUNTAINS (2021)
    Canadian Science Publishing
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    Publication Date: 2021-02-04
    Description: Fagus sylvatica is widely distributed across Europe thanks to its high adaptability in a wide variety of soils and climate. Microbial communities are essential for maintaining forest soil quality and are responsible for forest ecosystem functioning; the ability of soil microorganisms to respond to abiotic stressors (e.g. organic carbon losses, water scarcity, temperature changes), is crucial under ongoing environmental changes and also supports tree health. In this study, soil samples were collected from pure beech plots as part of the COST Action project CLIMO to find differences in microbial community characteristics and evaluate the effects of soil properties on microbial communities across altitude, latitude and longitude gradients. Positive relationships were found between organic carbon content and both microbial abundance and dehydrogenase activity. Dehydrogenase and catalase activities were altitude-correlated and microbial activities were longitude-correlated. In the most southern beech plot, microbial community was abundant and displayed high activities. This shows that microbial communities could help tree populations to better adapt to predicted changes in environmental conditions in the future. We suggest that research into forest health and beech performance should also test soil microbial enzymatic activity, in particular under changing climate conditions, to assist in identifying adaptation strategies.
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    Cost implications of cluster plot design choices for precise estimation of forest attributes in landscapes and forests of varying heterogeneity (2021)
    Canadian Science Publishing
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    Publication Date: 2021-08-11
    Description: Tradeoffs occur when deciding between improving forest inventory precision by increasing sample size or by augmenting cluster plot design factors like size or subplot separation distance. The nature of these tradeoffs changes with variation in type and scale of the spatial pattern of the attribute of interest. In order to understand the impacts of relationships between type and scale of spatial heterogeneity and cluster plot design efficiency, we constructed a factorial simulation experiment and analysed relationships between forest inventory cost, cluster plot design factors, and different spatial heterogeneity scenarios constructed via simulation. To calculate cost, we constructed a cost model that accounted for both on- and between-plot costs. We found that type and scale of heterogeneity have important implications for plot design choices. Homogeneous stands and landscapes are the least-costly to inventory. Subplot area and count have stronger impacts than subplot separation on cost efficiency, particularly in landscapes with aggregated forest patterns and in stands with homogeneous tree patterns. We discuss results in the context of the physical interaction between cluster plot geometry and spatial patterns at different scales, provide computer code for simulations, and suggest principles that forest inventory cluster plot design specialists should consider when designing inventories.
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    New genetically distinct phytoplasmas and insect carriers associated with pine tree disease revealed by a survey in Curonian Spit, Lithuania (2021)
    Canadian Science Publishing
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    Publication Date: 2021-08-11
    Description: Our previous studies reported that phytoplasma was the causative agent of the pine disease in Curonian spit, Lithuania. In this study, insects from diseased pine trees and their adjacent areas were collected from 2016 to 2019 to further identify potential insect vectors that spread phytoplasmas. A total of 1018 phloem-feeding insects (order Hemiptera) were identified, 98.62% of which were aphids (Aphididae), and no known phytoplasma vectors were found. Results from semi-nested PCR using phytoplasma-universal primers revealed that phytoplasmas were detected in scots pine aphids (Cinara pini), waxy grey pine needle aphids (Cinara pineti), and species-unknown aphids. Further sequence analysis and virtual RFLP analysis of aphid-harbored phytoplasma strains indicated that they were closely related to ‘Candidatus Phytoplasma pini’ (16SrXXI-A), but mainly 16SrXXI-A variants, which were also main strains identified in diseased pine trees. In addition, three new phytoplasma subgroups were delineated in the present study. Subgroups 16SrXXI-C and 16SrXXI-D were unveiled from previously identified (but classification was overlooked) Lithuanian pine phytoplasma strains. Subgroup 16SrXXI-E was discovered from the newly identified aphid-harbored phytoplasmas. Further transmission trial study on these aphids will provide insights into the epidemiology, and pathosystem of pine phytoplasma diseases, as well as the disease management.
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    Evaluation of mapped-plot variance estimators across a range of partial nonresponse in a post-stratified national forest inventory (2021)
    Canadian Science Publishing
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    Publication Date: 2021-08-10
    Description: When conducting a forest inventory, sometimes portions of plots cannot be measured due to inaccessibility. Two primary methods have been presented to account for partial nonresponse in the estimation phase: 1) use a ratio-to-size estimator, or 2) apply an adjustment factor to all plot observations in proportion to the missing area. Both approaches provide identical estimates of the population mean, but the estimates of variance differ when partial nonresponse is present. Variance estimator performance was examined for a range of population forest area and partial nonresponse proportions in the sample. The ratio-to-size variance estimator performed unbiasedly with respect to simulation results, but the adjustment factor variance estimates were biased with the magnitude and direction dependent upon the forest area proportion and amount of partial nonresponse. The bias is relatively small when the partial nonresponse is small, which is often the case; however, the ratio-to-size method is preferred to ensure accurate variance estimation for a wide range of circumstances.
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    BIOCHAR IN TEMPERATE SOILS: OPPORTUNITIES AND CHALLENGES (2021)
    Canadian Science Publishing
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    Publication Date: 2021-08-12
    Description: Biochar, a carbon-rich material produced by the pyrolysis of organic residues, is frequently used as a soil amendment to enhance soil fertility and improve soil properties in tropical climates. However, in temperate agriculture, the impact of biochar on soil and plant productivity remains uncertain. The objective of this review is to give an overview of the challenges and opportunities of using biochar as an amendment in temperate soils. Among the various challenges, the type of feedstock and the conditions during pyrolysis produces biochars with different chemical and physical properties, resulting in contrasting effects on soils and crops. Furthermore, biochar aging, biochar application rates and its co-application with mineral fertilizer and/or organic amendments add further complexity to our understanding of the soil-amendment-plant continuum. Although its benefits on crop yield are not yet well demonstrated under field studies, other agronomic benefits of biochar in temperate agriculture have been documented. In this review, we proposed a broader view of biochar as a temperate soil amendment, moving beyond our current focus on crop productivity, and instead target its capacity to improve soil properties. We explored biochar’s benefits in remediating low productive agricultural lands, and its environmental benefits through long-term carbon sequestration and reduced nutrient leaching while curtailing our reliance on fertilizer input. We also discussed the persistence of beneficial impacts of biochar in temperate field conditions. We concluded biochar displays great prospective to improve soil health and its productivity, enhance plant stress resilience, mitigate greenhouse gas emissions and restore degraded soils in temperate agriculture.
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    Airborne laser scanning for quantifying criteria and indicators of sustainable forest management in Canada (2021)
    Canadian Science Publishing
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    Publication Date: 2021-07-01
    Description: Airborne laser scanning (ALS) has emerged as a technology capable of generating descriptors of vegetation structure and best available terrain information. Research and operational implementations of ALS data have highlighted their value for characterizing forest structure and generating spatially explicit and objective spatial coverages and mapping products for forest management. Continued emphasis to enhance forest stewardship is promoting novel methods to integrate ALS to detail non-timber ecosystem values like habitat, soil, and water. Standardized criteria and indicator frameworks such as the Canadian Council of Forest Ministers provide a reliable starting point for where ALS has opportunities to characterize ecosystems objectively regardless of location. In this review of primarily Canadian work, we highlight how ALS is becoming an increasingly viable technology for deriving meaningful indicators to meet sustainable forest management criteria. We review and highlight the value of ALS for quantifying indicators of biological diversity, ecosystem condition and productivity, soil and water, and the role of forests in global ecological cycles. We conclude by highlighting the need for increased education, tech transfer, flexible software, and reporting frameworks alongside five key considerations for using ALS to derive meaningful indicators of sustainable forest management.
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    Introduction: Ecology and silviculture of temperate mixedwood forests (2021)
    Canadian Science Publishing
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    Publication Date: 2021-07-01
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    Partial special issue: Temperate mixedwood forests: ecology and management of hardwood–softwood mixtures (2021)
    Canadian Science Publishing
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    Publication Date: 2021-07-01
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    Dynamic treatment units in forest planning using cell proximity (2021)
    Canadian Science Publishing
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    Publication Date: 2021-07-01
    Description: In forest management planning, the dynamic treatment unit (DTU) approach has become an increasingly relevant alternative to the traditional planning approach using fixed stands, due to improved remote sensing techniques and optimization procedures, with the potential for the higher goal fulfillment of forest activities. For the DTU approach, the traditional concept of fixed stands is disregarded, and forest data are kept in units with a high spatial resolution. Forest operations are planned by clustering cells to form treatment units for harvest operations. This paper presents a new model with an exact optimization technique for forming DTUs in forest planning. In comparison with most previous models, this model aims for increased flexibility by modelling the spatial dimension according to cell proximity rather than immediate adjacency. The model is evaluated using a case study with harvest flow constraints for a forest estate in southern Sweden, represented by 3587 cells. The parameter settings differed between cases, resulting in varying degrees of clustered DTUs, which caused relative net present value losses of up to 4.3%. The case without clustering had the lowest net present value when considering entry costs. The solution times varied between 2.2 s and 42 min 6 s and grew rapidly with increasing problem size.
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    A species-specific, site-sensitive maximum stand density index model for Pacific Northwest conifer forests (2021)
    Canadian Science Publishing
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    Publication Date: 2021-08-01
    Description: Maximum stand density index (SDIMAX) models were developed for important Pacific Northwest conifers of western Oregon and Washington, USA, based on site and species influences and interactions. Inventory and monitoring data from numerous federal, state, and private forest management groups were obtained throughout the region to ensure a wide coverage of site characteristics. These observations include information on tree size, number, and species composition. The effects and influence on the self-thinning frontier of plot-specific factors such as climate, topography, soils, and geology, as well as species composition, were evaluated based on geographic location using a multistep approach to analysis involving linear quantile mixed models, random forest, and stochastic frontier functions. The self-thinning slope of forest stands dominated by Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) was found to be –1.517 and that of stands dominated by western hemlock (Tsuga heterophylla (Raf.) Sarg.) was found to be –1.461, leading to regionwide modelled SDIMAX values at the 95th percentile of 1728 and 1952 trees per hectare, respectively. The regional model of site-specific SDIMAX will support forest managers in decision-making regarding density management and species selection to more efficiently utilize site resources toward healthy, productive forests.
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    Lodgepole pine and interior spruce radial growth response to climate and topography in the Canadian Rocky Mountains, Alberta (2021)
    Canadian Science Publishing
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    Publication Date: 2021-07-01
    Description: Climate change may have spatially variable impacts on growth of trees in topographically diverse environments, making generalizing across broad spatial and temporal extents inappropriate. Therefore, topography must be considered when analyzing growth response to climate. We address these topo-climatic relationships in the Canadian Rocky Mountains, focusing on lodgepole pine (Pinus contorta Douglas ex Louden) and interior spruce (Picea glauca (Moench) Voss × Picea engelmannii hybrid Parry) growth response to climate, Palmer drought severity index (PDSI), aspect, and slope angle. Climate variables correlate with older lodgepole pine growth on south- and west-facing slopes, including previous August temperature, winter and spring precipitation, and previous late-summer and current spring PDSI, but younger lodgepole pine were generally less sensitive to climate. Climate variables correlate with interior spruce growth on all slope aspects, with winter temperature and PDSI important for young and old individuals. Numerous monthly growth–climate correlations are not temporally stable, with shifts over the past century, and response differs by slope aspect and angle. Both species are likely to be negatively affected by moisture stress in the future in some, but not all, topographic environments. Results suggest species-specific and site-specific spatiotemporally diverse climate–growth responses, indicating that climate change is likely to have spatially variable impacts on radial growth response in mountainous environments.
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    Comparison of time-based versus state–space stand growth models for tropical hybrid Eucalyptus clonal plantations in Sumatera, Indonesia (2021)
    Canadian Science Publishing
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    Publication Date: 2021-08-01
    Description: The pulp and paper industry in Indonesia is the tenth largest producer in the world, with Acacia and Eucalyptus as the main genera used for production; however, limited publications exist related to Eucalyptus growth models in Indonesia compared with other regions. Time-based models have been developed in which height, stand density, and basal area are predicted based on initial conditions and age. In contrast, a state–space approach utilizes the rate of change of these three state variables. Previous direct comparisons of these two approaches are generally limited. Consequently, the objective of this study was to compare two stand-level growth modeling approaches for Eucalyptus hybrid species on Sumatera (Sumatra) Island using both time-based and state–space methods. Our results indicate that dynamic models using either time-based or state–space approaches are adequate for predicting stand parameters to rotation age. A modified Bazukis matrix indicated that the behavior of both methods produced reliable predictions that were biologically reasonable in terms of stand development; however, the time-based approach provided better performance than the state–space approach on a variety of equivalence tests and goodness-of-fit statistics. Overall, the analysis highlights the advantages and disadvantages of these two commonly used, yet highly contrasting, stand-level growth modeling approaches, which need further consideration and evaluation.
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    An adapted Weibull function for agricultural applications (2021)
    Canadian Science Publishing
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    Publication Date: 2021-06-25
    Description: The Weibull function is applied extensively in the life sciences and engineering but underused in agriculture. The function was consequently adapted to include parameters and metrics that increase its utility for characterizing agricultural processes. The parameters included initial and final dependent variables (Y0 and YF, respectively), initial independent variable (x0), a scale constant (k), and a shape constant (c). The primary metrics included mode, integral average, domain, skewness, and kurtosis. Nested within the Weibull function are the Mitscherlich and Rayleigh functions where c is fixed at 1 and 2, respectively. At least one of the three models provided an excellent fit to six example agricultural datasets, as evidenced by large adjusted coefficient of determination (RA2 ≥ 0.9266), small normalized mean bias error (MBEN ≤ 1.49%), and small normalized standard error of regression (SERN ≤ 8.08%). The Mitscherlich function provided the most probable (PX) representation of corn (Zea mays L.) yield (PM = 87.2%); Rayleigh was most probable for soil organic carbon depth profile (PR = 96.4%); and Weibull was most probable for corn seedling emergence (PW = 100%), nitrous oxide emissions (PW = 100%), nitrogen mineralization (PW = 58.4%), and soil water desorption (PW = 100%). The Weibull fit to the desorption data was also equivalent to those of the well-established van Genuchten and Groenevelt–Grant desorption models. It was concluded that the adapted Weibull function has good potential for widespread and informative application to agricultural data and processes.
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    Mixedwood management positively affects forest health during insect infestations in eastern North America1 (2021)
    Canadian Science Publishing
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    Publication Date: 2021-07-01
    Description: Mixedwood stands are composed of hardwoods and softwoods, with neither comprising greater than 75%–80% of basal area or aboveground biomass. By conferring associational resistance and greater resilience to forests when stressed or disturbed, the more diverse composition of mixedwood stands contributes to forest health. We analyzed three examples where mixedwood stands are more resistant to insect infestations in eastern North America. In balsam fir (Abies balsamea L. Mill.) and spruce (Picea spp.) forests, susceptibility and vulnerability to spruce budworm infestations is reduced with increasing hardwood density. In mid-Atlantic oak-dominated forests, oak mortality following gypsy moth infestations was much greater in oak-dominated forests than in oak–pine mixedwoods, while pine mortality during southern pine beetle infestations was greater in pine-dominated forests than in oak–pine mixedwoods. Overall, mixedwood stands have greater resistance to infestations of defoliators and bark beetles and recover more rapidly from disturbances, reducing economic losses associated with tree mortality and mitigating short-term impacts to ecosystem functioning resulting from insect damage, especially carbon sequestration. Finally, we discuss challenges and opportunities for mixedwood management to minimize insect damage. Management strategies that incorporate mixedwood stands may provide better continuity in supply of forest products and ecosystem services in the face of projected increases in insect infestations associated with changing climate.
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    Sector subsampling for basal area ratio estimation: an alternative to big BAF sampling (2021)
    Canadian Science Publishing
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    Publication Date: 2021-08-01
    Description: Big basal area factor (big BAF) sampling is a widely used subsampling method to select measure-trees. Several studies have shown big BAF sampling to be an efficient sampling scheme. In this study, we use sector sampling (Smith et al. 2008, For. Sci. 54: 67–76) as an alternative subsample selection method. Based on some simulated mapped stands derived from three balsam fir (Abies balsamea (L.) Mill.) spacing trials in western Newfoundland, we show that sector subsampling is comparable to big BAF sampling in terms of estimated mean basal area ratios and their associated standard errors. Differences between big BAF sampling and sector sampling methods showed less than 1% difference across the three sites. As with big BAF sampling, changes in sample intensity had no significant (p 〈 0.05) effects on the accuracy of estimating mean biomass to basal area ratios and the resulting estimated mean biomasses per unit area.
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    Pedological trends and implications for forest productivity in a Holocene soil chronosequence, Calvert Island, British Columbia, Canada (2021)
    Canadian Science Publishing
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    Publication Date: 2021-06-18
    Description: Chronosequence studies of soil formation and ecosystem development provide important insights into the pathways and rates of change occurring on centennial and millennial time scales. In cool or temperate humid environments, Podzols are the predominant soil type formed under coniferous forests in coarse-textured parent material and have been a major focus of chronosequence studies. This study examined the rate and mechanisms of Podzol development and related forest productivity in a sand dune chronosequence in a hypermaritime climate in coastal British Columbia (BC). The sequence spans 10 760 ± 864 yr over eight sites and is the first documented chronosequence in coastal BC to span most of the Holocene Epoch. Soil samples from each genetic horizon were analyzed for bulk density, pH and concentrations of total carbon (C), pyrophosphate- and oxalate-extractable aluminum (Al) and iron (Fe), and total elements. Within ∼3500 yr, a mature Podzol had formed, with cemented horizons (ortstein and placic) present. Organo-metallic complexation appeared to be the dominant mechanism involved in podzolization. Despite a mild, moist climate conducive to chemical weathering, all soils had similarly low values for the chemical index of alteration, suggesting that congruent dissolution of primary minerals may be occurring. Ecosystem retrogression is apparent in the latter stages of the chronosequence — a phenomenon not previously documented in coastal BC. Further research is needed to examine the interactions of nutrient limitation, soil physical barriers, and other possible drivers of ecosystem retrogression.
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    Relative importance of climate, vegetation, and spatial factors in the community and functional composition of wood-inhabiting fungi in discontinuously distributed subalpine spruce forests (2021)
    Canadian Science Publishing
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    Publication Date: 2021-07-01
    Description: Wood-inhabiting fungi are critically important for the decomposition of coarse woody debris (CWD). To evaluate the relative importance of climate, vegetation, and spatial factors in the functional composition of fungal communities that inhabit CWD in discontinuously distributed subalpine Hondo spruce (Picea jezoensis (Sieb. & Zucc.) Carr. var. hondoensis (Mayr) Rehder) forests, a metabarcoding analysis was conducted on spruce deadwood samples obtained from six subalpine forests in central Japan using a high-throughput DNA sequencing technique. We detected 454 fungal operational taxonomic units (OTUs) from 67 spruce CWDs and determined that spatial factors explained a larger fraction of community variation than environmental (climate and vegetation) factors at all six study sites. However, environmental factors explained a larger fraction than spatial factors if we excluded data from one site that is geographically distant from other study sites. The OTU number and the occurrence of brown-rot fungi were positively associated with mean annual temperature and negatively associated with mean annual precipitation. Similarly, the principal component of forest vegetation significantly affected the OTU number and occurrence of brown-rot fungi. Precipitation seasonality was positively associated with the OTU number of undefined saprotrophs. These results suggest that fungal OTUs belonging to different functional groups respond differently to environmental variables.
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    Mixtures of airborne lidar-based approaches improve predictions of forest structure (2021)
    Canadian Science Publishing
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    Publication Date: 2021-08-01
    Description: The most common method for modeling forest attributes with airborne lidar, the area-based approach, involves summarizing the point cloud of individual plots and relating this to attributes of interest. Tree- and voxel-based approaches have been considered as alternatives to the area-based approach but are rarely considered in an area-based context. We estimated three forest attributes (basal area, overstory biomass, and volume) across 1680 field plots in Arizona and New Mexico. Variables from the three lidar approaches (area, tree, and voxel) were created for each plot. Random forests were estimated using subsets of variables based on each individual lidar approach and mixtures of each approach. Boruta feature selection was performed on variable subsets, including the mixture of all lidar-approach predictors (KS-Boruta). A corrected paired t test was utilized to compare six validated models (area-Boruta, tree-Boruta, voxel-Boruta, KS-Boruta, KS-all, and ridge-all) for each forest attribute. Based on significant reductions in error (SMdAPE), basal area and biomass were best modeled with KS-Boruta, while volume was best modeled with KS-all. Analysis of variable importance shows that voxel-based predictors are critical for the prediction of the three forest attributes. This study highlights the importance of multiresolution voxel-based variables for modeling forest attributes in an area-based context.
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    Mixedwood silviculture in North America: the science and art of managing for complex, multi-species temperate forests (2021)
    Canadian Science Publishing
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    Publication Date: 2021-07-01
    Description: Temperate mixedwoods (hardwood–softwood mixtures) in central and eastern United States and Canada can be classified into two overarching categories: those with shade-tolerant softwoods maintained by light to moderate disturbances and those with shade-intolerant to mid-tolerant softwoods maintained by moderate to severe disturbances. The former includes red spruce (Picea rubens Sarg.), balsam fir (Abies balsamea (L.) Mill.), or eastern hemlock (Tsuga canadensis (L.) Carr.) in mixture with northern hardwood species; the latter includes pine (Pinus) – oak (Quercus) mixtures. Such forests have desirable socio-economic values, wildlife habitat potential, and (or) adaptive capacity, but management is challenging because one or more softwood species in each can be limited by depleted seed sources, narrow regeneration requirements, or poor competitive ability. Appropriate silvicultural systems vary among mixedwood compositions depending on shade tolerance and severity of disturbance associated with the limiting softwoods, site quality, and level of herbivory. Sustainability of mixedwood composition requires that stand structure and composition be managed at each entry to maintain vigorous trees of species with different growth rates and longevities and to encourage development of advance reproduction or seed-producing trees of desired species. Regardless of silvicultural system, maintaining seed sources of limiting softwoods, providing suitable germination substrates, and controlling competition are critical. Here, we describe commonalities among temperate mixedwoods in central and eastern North America and present a framework for managing them.
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    Unmanned aerial vehicles (UAV)-based canopy height modeling under leaf-on and leaf-off conditions for determining tree height and crown diameter (case study: Hyrcanian mixed forest) (2021)
    Canadian Science Publishing
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    Publication Date: 2021-07-01
    Description: Tree height and crown diameter are two common individual tree attributes that can be estimated from unmanned aerial vehicle (UAV) images thanks to photogrammetry and structure from motion. This research investigates the potential of low-cost UAV aerial images to estimate tree height and crown diameter. Two successful flights were carried out in two different seasons corresponding to leaf-off and leaf-on conditions to generate a digital terrain model and a digital surface model, which were further employed in calculation of a canopy height model (CHM). The CHM was used to estimate tree height using low pass and local maximum filters, and crown diameter was estimated based on an inverse watershed segmentation algorithm. UAV-based tree height and crown diameter estimates were validated against field measurements and resulted in 3.22 m (10.1%) and 0.81 m (7.02%) root mean square errors, respectively. The results showed high agreement between our estimates and field measurements, with an R2 of 0.808 for tree height and an R2 of 0.923 for crown diameter. Generally, the accuracy of the results was considered acceptable and confirmed the usefulness of this approach for estimating tree heights and crown diameter.
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    Co-movement of prices between biofuel co-products in Canada: ethanol, electricity, and pellets (2021)
    Canadian Science Publishing
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    Publication Date: 2021-07-01
    Description: The potential emergence of a second-generation ethanol industry in Canada will depend on future production technologies and prices. Financial viability might be improved by producing cellulosic ethanol with co-products such as lignin pellets or electricity. Financial returns to ethanol production will depend on price variability and possible price spillovers among ethanol and its co-products. We use a multivariate BEKK–GARCH approach to investigate past mean price interactions and volatility spillovers between ethanol and electricity prices. Wood pellets are investigated in a univariate framework because of data constraints. Results show substantial price interactions and volatility spillovers among these products. If a second-generation ethanol industry emerges, co-production of products from common feedstocks may strengthen already established relationships between the prices of these energy products. These conditions could create increased risk and the clustering of high–low price fluctuations among co-products. For investors, results suggest that risk reduction strategies should protect against correlated volatility. For policy makers, results suggest that policies that target one commodity may lead to unintended impacts on co-product(s). In sum, understanding links between markets is important for designing future policies and for insights into how a second-generation ethanol industry may emerge.
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    Efficient synthetic generation of ecological data with preset spatial association of individuals (2021)
    Canadian Science Publishing
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    Publication Date: 2021-08-01
    Description: Many experiments cannot feasibly be conducted as factorials. Simulations using synthetically generated data are viable alternatives to such factorial experiments. The main objective of the present research is to develop a methodology and platform to synthetically generate spatially explicit forest ecosystems represented by points with a predefined spatial pattern. Using algorithms with polynomial complexity and parameters that control the number of clusters, the degree of clusterization, and the proportion of nonrandom trees, we show that spatially explicit forest ecosystems can be generated time efficiently, which enables large factorial simulations. The proposed method was tested on 1200 synthetically generated forest stands, each of 25 ha, using 10 spatial indices: Clark–Evans aggregation index; Ripley’s K; Besag’s L; Morisita’s dispersion index; Greig–Smith index; the size dominance index of Hui; index of nonrandomness of Pielou; directional index and mean directional index of Corral–Rivas; and size differentiation index of Von Gadow. The size of individual trees was randomly generated aiming at variograms such as real forests. We obtained forest stands with the expected spatial arrangement and distribution of sizes in less than 1 h. To ensure replicability of the study, we have provided free, fully functional software that executes the stated tasks.
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    Assessing the influence of climate on the growth rate of boreal tree species in northeastern Canada through long-term permanent sample plot data sets (2021)
    Canadian Science Publishing
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    Publication Date: 2021-07-01
    Description: Climate has a considerable influence on tree growth. Forest managers benefit from the empirical study of the historic relationship between climatic variables and tree growth to support forest management frameworks that are to be applied under scenarios of climate change. Through this research, we have utilized long-term permanent sample plot records, historic climate data sets, and linear mixed modelling techniques to evaluate the historic influence of climatic variables on the growth rates of major boreal tree species in Newfoundland and Labrador, Canada. For the commercially significant spruce and fir forests of the province, we found growing degree-days (GDD) to negatively correlate with tree productivity in warmer regions, such as much of Newfoundland (±1350 GDD), but positively correlate with growth in cooler regions, such as those in Labrador (±750 GDD). With respect to precipitation, environmental moisture was not on average a limiting factor to species productivity in the province. These dynamics have implications for the productivity of the spruce–fir forests of the study area when considered alongside contemporary climate projections for the region, which generally entail both a warmer and wetter growing environment.
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    Natural recovery of skid trails: a review (2021)
    Canadian Science Publishing
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    Publication Date: 2021-07-01
    Description: In recent years, the study of skid trail recovery processes has gained momentum. In this review, 121 studies on various aspects of skid trail recovery were evaluated to determine when, where, and how the dominant factors that influence the process of recuperation occur. These studies were located proportionally in the following forest biomes: temperate (60%), tropical (31%), and boreal (9%). Research focused mainly on soil physical properties to ascertain if there had been evidence of recovery. The majority of studies of a decade or less after abandonment demonstrated that heavily used skid trails had not recovered. On the contrary, lightly used skid trails did present full recoveries over the same time span. Soil recovery tended to occur in medium- to coarse-textured soils in temperate and boreal forests. Considering all forest biomes, the impacts of compaction persisted at least two to five decades after logging operations. The impacts were evident in diminished tree heights and volumes from trees growing on skid trails. The last 50 years of research indicates that skid trails, globally, do recover from compaction, albeit slowly.
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    Long-term evolution of composition and structure after repeated group selection over eight decades (2021)
    Canadian Science Publishing
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    Publication Date: 2021-07-01
    Description: In northeastern North America, group selection is frequently used in northern hardwood forests to maintain uneven-aged stand structure and promote regeneration of tree species spanning a range of shade tolerances. For this study, long-term application of group selection at the Bartlett Experimental Forest, New Hampshire, USA, provided a unique opportunity to address cohort- and stand-level progression after 80 years of treatment. Cohort-level evolution reflected successional and developmental dynamics associated with even-aged forest systems, whereas aggregate stand-level conditions were consistent with expectations for uneven-aged systems. As cohorts aged, diameter distributions progressed towards descending monotonic forms and species composition transitioned from shade-intolerant species to shade-tolerant species. Standing deadwood and downed woody material in cohorts followed trajectories of aging even-aged stands through time. Although American beech (Fagus grandifolia Ehrh.) was a primary species across cohorts and at the stand level, stand-level regeneration included a mixture of ecologically and commercially valuable species. These long-term results offer important insights into emergent cohort- and stand-level conditions and processes that may affect continued recruitment of desirable compositional and structural conditions in stands managed using group selection over numerous cutting cycles.
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    Stand density biases the estimation of the site index especially on dry sites (2021)
    Canadian Science Publishing
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    Publication Date: 2021-07-01
    Description: The site index (SI) has been widely used in forest management and silviculture. It relies on the assumption that the height of dominant trees in a stand is independent from the local density. However, research on climate change suggests that under certain moisture stress conditions, this may not hold. Here, based on 29 plots from five long-term research experiments, we tested the effect of local stand density on the SI of Norway spruce (Picea abies (L.) H. Karst). With generalized additive models (GAMM), we analyzed the effect of stand structure and climate predictors on SI. The two evaluated models revealed that local stand density and age had a significant effect on SI (p ≤ 0.001), showing a clear negative trend especially significant on sites with poor and dry soils, which may reduce the SI by a maximum of approximately 4 m for an increase in density of between 400 and 600 trees/ha. We stress that the physiological characteristics of Norway spruce, flat-rooting system and xeromorphism, especially when growing in pure stands, may explain these effects. Thus, density control and growth in mixtures may help to reduce the water stress and losses in height growth under future climate conditions.
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    Competition effects in breeding value prediction of forest trees (2021)
    Canadian Science Publishing
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    Publication Date: 2021-07-01
    Description: Competition is a concern for tree breeding because of its potential to reduce the genetic gain. Competition, if not accounted for in the analytical model, can potentially introduce a source of bias in genetic parameter estimation and breeding value prediction. This study modelled competition between trees in 20 Swedish progeny trials of Norway spruce (Picea abies (L.) Karst.), Scots pine (Pinus sylvestris L.), and lodgepole pine (Pinus contorta Douglas ex Loudon). The competition model assumed a tree has a direct additive genetic effect, which affects the tree’s own phenotype, and an indirect additive effect, which affects the phenotypes of its neighbours. Genetic parameters were estimated via a factor analytic structure in which separate indirect effects were considered for each neighbour, or via a combined indirect effect approach. We analysed diameter, as it is the trait that can be expected to be affected most by competition. Competition at the genetic level was detected in 17 of the 20 trials analysed. In most cases, the ratio of indirect to direct additive variance was less than 20% and no major changes in ranking resulted. At this stage, there is little incentive to incorporate indirect effects into program-wide genetic evaluation models. The added complexity is not commensurate with the benefit that would be gained.
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    Sampling with probability proportional to prediction (3P sampling) using covariates derived from spherical images (2021)
    Canadian Science Publishing
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    Publication Date: 2021-08-01
    Description: Using a two-phase sampling approach with systematic selection of large samples of covariates followed by a sampling with probability proportional to prediction (3P sampling) process to subsample field measures of the parameters of interest can be an efficient design to sample larger forest areas. To assist in obtaining predictions for each sample plot consistently and rapidly, we propose using a 360° spherical camera. In this study, three covariates derived from spherical images were evaluated: (i) basal area (P[BA]); (ii) sum of squared heights per hectare (P[SHT]); and (iii) stem fraction (P[SF]). These covariates were used to estimate volume. Sample simulations showed no biases in volume estimates for any of the three covariates. Overall, P[SF] had the lowest standard error percentages across different simulated sample sizes (10% for five subsamples to 2.5% for 50 subsamples), even though it had the lowest correlations with field volume (correlation = 0.30–0.31). This may be a result of the relatively consistent stand conditions within the study site. Based on our results, standard errors of 5% were obtainable with measurement fractions of about 25% of the number of image-based predictions when using P[SF] or P[BA] and 75% when using P[SHT].
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    Advancements in forest mensuration and biometrics in the artificial intelligence era (2021)
    Canadian Science Publishing
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    Publication Date: 2021-08-01
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    Advances in forest mensuration and biometrics, featuring papers presented at the 2020 Western Mensurationists Conference (2021)
    Canadian Science Publishing
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    Publication Date: 2021-08-01
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    Impact of stem lean on estimation of Douglas-fir (Pseudotsuga menziesii) diameter and volume using mobile lidar scans (2021)
    Canadian Science Publishing
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    Publication Date: 2021-08-01
    Description: The value of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco), which is the predominant commercial species in the Pacific Northwest, depends on tree verticality; trees with the same dimensions can differ substantially in value due to lean. The objective of this study was to assess the impact of tree leaning on estimation of stem dimensions using high-density terrestrial mobile lidar point clouds. We estimated lean with two metrics: the horizontal distance between stem centers at 1.3 m and 18 m, and the mean of seven successive lean angles along the tree bole (at 1, 3, 5, 7, 10, 12, and 15 m). For modeling, we used four existing taper equations and three existing volume equations. For trees leaning 〉2°, we enhanced the existing volume models by including lean as a predictor. Because lean estimates depend on the distribution and number of points describing the stem, we found that including the distance from scanner to tree improved the computed volume. When diameter at breast height was replaced with diameter at heights between 7 and 10 m, the volume models for leaning trees improved significantly, whereas the vertical trees had favorable results with heights between 5 and 15 m. Our study suggests that lean magnitude improves the estimation of stem volume when lean is 〉2°.
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    A financial analysis of four carbon offset accounting protocols for a representative afforestation project (southern Ontario, Canada) (2021)
    Canadian Science Publishing
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    Publication Date: 2021-07-01
    Description: Forestry projects participate in carbon markets by sequestering carbon dioxide equivalent (CO2e) and producing carbon offsets. The creation of forest-based offsets is guided by protocols that dictate how sequestered CO2e is converted into marketable offsets. Existing protocol designs aim to produce offsets that meet sustainability requirements, while providing financial incentives for landowner participation. However, limited Canadian uptake implies that current financial incentives are insufficient to encourage the production of carbon offsets via private landowners. Here we consider various design features of four protocols and their financial implications for an illustrative afforestation project in southern Ontario, Canada. We explore the protocols (two tonne–tonne protocols and two tonne–year protocols) under two afforestation project management systems (“no-harvest” and “harvest” management scenarios). Results indicate that a project that terminates in a harvest is not economically attractive at current CO2e prices under any protocol design at a scale likely to be undertaken in southern Ontario, Canada. Projects that do not conclude in harvest are generally more attractive. Tonne–tonne protocols that pay upfront for sequestered CO2e improve the economic attractiveness of afforestation projects, but the delayed realization of the value of offset credits under tonne–year protocols reduces the economic attractiveness of these projects. We discuss these results in light of the choices facing afforestation project proponents and offset protocol designers (including governments) in general, and provide detailed insights into the financial dynamics of the Canadian case.
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    Contemporary status, distribution, and trends of mixedwoods in the northern United States (2021)
    Canadian Science Publishing
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    Publication Date: 2021-07-01
    Description: As interest in managing and maintaining mixedwood forests in the northern United States (US) grows, so does the importance of understanding their abundance and distribution. We analyzed Forest Inventory and Analysis data for insights into mixedwood forests spanning 24 northern US states from Maine south to Maryland and westward to Kansas and North Dakota. Mixedwoods, i.e., forests with both hardwoods and softwoods present but neither exceeding 75%–80% of composition, comprise more than 19 million hectares and more than one-quarter of the northern US forest. They are most common in the Adirondack – New England, Laurentian, and Northeast ecological provinces but also occur elsewhere in hardwood-dominated ecological provinces. These mixtures are common even within forest types nominally categorized as either hardwood or softwood. The most common hardwoods within those mixtures were species of Quercus and Acer, and the most common softwoods were species of Pinus, Tsuga, and Juniperus. Although mixedwoods exhibited stability in total area during our analysis period, hardwood saplings were prominent, suggesting widespread potential for eventual shifts to hardwood dominance in the absence of disturbances that favor regeneration of the softwood component. Our analyses suggest that while most mixedwood plots remained mixedwoods, harvesting commonly shifts mixedwoods to either hardwood- or softwood-dominated cover types, but more specific information is needed to understand the causes of these shifts.
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    Potential for individual tree monitoring in ponderosa pine dominated forests using unmanned aerial system structure from motion point clouds (2021)
    Canadian Science Publishing
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    Publication Date: 2021-08-01
    Description: Characterization of forest structure is important for management-related decision making, monitoring, and adaptive management. Increasingly, observations of forest structure are needed at both finer resolutions and across greater extents to support spatially explicit management planning. Unmanned aerial system (UAS) based photogrammetry provides an airborne method of forest structure data acquisition at a significantly lower cost and time commitment than existing methods such as airborne laser scanning (LiDAR). This study utilizes nearly 5000 stem-mapped trees in ponderosa pine (Pinus ponderosa Lawson & C. Lawson) dominated forests to evaluate several algorithms for detecting individual tree locations and characterizing crown area across tree sizes. Our results indicate that adaptive variable window detection methods with UAS-based canopy height models have greater tree detection rates compared with fixed window analysis across a range of tree sizes. Using the UAS approach, probability of detecting individual trees decreases from 97% for dominant overstory to 67% for suppressed understory trees. Additionally, crown radii were correctly determined within 0.5 m for approximately two-thirds of sampled trees. These findings highlight the potential for UAS photogrammetry to characterize forest structure through the detection of trees and tree groups in open-canopy ponderosa pine forests. Further work should investigate how these methods transfer to more diverse species compositions and forest structures.
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    Detection of wood decay and cavities in living trees: a review (2021)
    Canadian Science Publishing
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    Publication Date: 2021-07-01
    Description: It has been established that wood decay and cavities in tree stems contribute significantly to tree failures. Several techniques have been reported by researchers for detecting wood decay and cavities in living trees. These techniques are reviewed in this study under two broad categories: invasive and noninvasive methods. The invasive methods include traditional (decay detecting drill, increment borer, and boroscope), radiographic, acoustic, and electrical resistivity techniques. The noninvasive methods comprise microwave scanning, magnetic resonance imaging, X-ray tomography, and traditional techniques involving the use of mallets. Two or more methods are usually combined to investigate the health status of a tree for comparison and validation of results. The prospects and challenges of the various techniques in diagnosing wood decay, cavities, and other structural defects in living trees are reported. This review aims to help researchers in this field identify areas of further work towards the efficient monitoring and management of forest and urban trees.
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    The response of alfalfa genotypes to different concentrations of mobile aluminium (2021)
    Cambridge University Press
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    Publication Date: 2021-09-07
    Description: The morphological traits of alfalfa under acid soil conditions with different mobile aluminium (Al) concentrations were investigated. The study site was Vėžaičiai Branch of the Lithuanian Research Centre for Agriculture and Forestry, 55°70 N, 21°49 E. The experiment featuring the 30 most Al-tolerant alfalfa accessions (populations and cultivars), determined from laboratory trials was established on a Bathygleyic Dystric Retisol in 2018. In 2019 and 2020, the biological and morphological traits were evaluated: plant regrowth, plant height before flowering, wintering, leafiness, stem thickness, plant vigour, stem density, seed yield and resistance to spring black stem leaf spot. The resistance of alfalfa to mobile Al toxicity was determined using a filter-based screening method of selection cycles C1 and C2. The accessions grown in the soil with mobile Al (20.6–23.4 mg/kg) showed better tolerance to Al toxicity in the cycle C2. The hypocotyl tolerance index of these accessions was better at 8, 16, 32 and 64 mm AlCl3 concentrations in the cycle C2. The correlation analysis showed strong significant positive and negative relationships between the morphological traits. A cluster analysis showed that the accessions, grown in the soil with mobile Al (20.6–23.4 mg/kg) were the most resistant to Al toxicity in the cycle C2. These accessions produced a better seed yield and demonstrated lower values of morphological traits compared to cluster 2. Also, these accessions are considered as tolerant to mobile Al toxicity and might be used as donors in breeding for Al toxicity tolerance.
    Print ISSN: 0021-8596
    Electronic ISSN: 1469-5146
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    Inoculant, nitrogen and phosphorus improves photosynthesis and water-use efficiency in soybean production (2021)
    Cambridge University Press
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    Publication Date: 2021-09-07
    Description: Soybean yield within the Southern Africa falls below its potential despite similar climatic conditions across some agroecologies, replicable agronomic management practices and introduced improved varieties. Understanding physiological processes and water-use efficiency (WUE) of soybean offer information on bridging this yield gap. A field study was conducted in 2017 and 2018 seasons in two agroecologies (Angonia and Ruace) in Mozambique to evaluate the effects of Bradyrhizobium diazoefficiens strain USDA110 formerly known as Bradyrhizobium japonicum inoculant, nitrogen and phosphorus on nodulation, physiology and yield of non-promiscuous (Safari) and promiscuous (TGx 1740-2F) soybean varieties. Data on transpiration, photosynthesis, leaf area index, radiation interception and WUE from the beginning of flowering to maturity were collected. Transpiration rate varied considerably with interaction between locations, growth stages, varieties and treatments. At podding, phosphorus-treated soybean at Angonia transpired less (6.3 mmol/m2/s) than check plants (6.6 mmol/m2/s). Photosynthesis rate and WUE were distinct with variety, growth stages and inputs within agroecologies. For instance, in Angonia 2018 season, phosphorus fertilized TGx 1740-2F photosynthesized more at flowering (25.3 μmol/m2/s) while the lowest was phosphorus-treated Safari at podding with 17.2 μmol/m2/s. At the same site in 2017, inoculated soybean photosynthesized more at 22.8 μmol/m2/s leading to better WUE of 3.6 that corresponded to 2894 kg/ha yield. Overall, soybean WUE was higher when inoculated than N-treated, while P application yielded better. Results from this study will complement breeders’ effort in developing phosphorus efficient varieties suited for a wide range of changing climatical conditions.
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    Correction: Deadman anchoring design for cable logging: a new approach (2021)
    Canadian Science Publishing
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    Publication Date: 2021-09-01
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    Fine-scale altitudinal gradients influence the relationships between structural attributes and aboveground biomass in Central Africa (2021)
    Canadian Science Publishing
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    Publication Date: 2021-09-01
    Description: There is increasing interest in altitude effects on structural attributes and aboveground biomass (AGB) in tropical forests. However, we continue to lack a clear understanding of relationships between structural attributes and AGB along altitudinal gradients in Central Africa. Using a new network of 76 permanent plots of 0.5 ha, the relationships between structural attributes and AGB were explored along fine-scale altitudinal gradients in the Republic of Congo. We chose four fine-scale altitudinal gradients (71–350 m, 350–550 m, 550–650 m, and 650–853 m) and measured the diameter and heights of 4192 trees with a ≥10 cm diameter and calculated the structural attributes and the AGB for each 0.5 ha plot. For a given diameter, trees were shorter and had narrower crowns in the altitudinal gradient of 71–350 m than in the other altitudinal gradients. The relationships between structural attributes and AGB differ along fine-scale altitudinal gradients, with higher stem density, wood density, crown depth, and AGB for the altitudinal gradient of 71–350 m. These results provide important advances in our understanding of the relationships between structural attributes and AGB along fine-scale altitudinal gradients in Central Africa. They should improve AGB estimates for the low altitudinal gradient when combined with other field and remotely sensed data sets in Central Africa.
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    Bioenergy yield of Eucalyptus urophylla clones and its relationship with the mean annual increment of wood volume (2021)
    Canadian Science Publishing
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    Publication Date: 2021-09-01
    Description: This study aimed to evaluate the energy yield and wood characteristics of Eucalyptus urophylla S.T.Blake clones with different mean annual increment (MAI) of wood volume. The clones presented MAIs of 39.2, 54.1, and 70.0 m3·ha−1·year−1 in the field experiment at 6 years after planting when the trees were cut down to evaluate the wood basic density and higher heating values. The energy density, dry mass, and energy yield were estimated. The MAI of E. urophylla clones influenced the wood basic density, dry mass, and energy yield, but did not influence the higher heating value and energy density. Clone 3 had the highest MAI as well as higher energy yield and dry mass, but lower wood basic density. The difference between the most and the least productive clones was 242 648 MJ·ha−1·year−1. The results reinforce the importance of evaluating the wood quantity production (MAI) when selecting E. urophylla clones for energy purposes.
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    Preliminary assessments of shoot cold tolerance for American elm bred for enhanced tolerance to Dutch elm disease (2021)
    Canadian Science Publishing
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    Publication Date: 2021-09-01
    Description: Although Dutch elm disease (DED) is the primary threat to American elm (Ulmus americana L.), we hypothesized that shoot freezing injury may also limit tree productivity and survival in the north. We assessed shoot cold tolerance and field winter injury of American elm bred for DED tolerance planted in Lemington, Vermont. We tested for differences in cold tolerance associated with date, maternal DED tolerance sources, paternal sources from plant hardiness zones 5a, 6a, and 6b (determined using data from 1996 to 2005), and the interactions of these. Cold tolerance was greatest in the winter, followed by fall and then spring. For all dates, cold tolerance never differed between maternal DED tolerance sources. However, in mid-winter, paternal sources from zone 5a (coldest zone) were significantly more cold tolerant than sources from zone 6b (warmest zone), and sources from zone 6a were intermediate. Field freezing injury confirmed that shoots were only marginally cold tolerant relative to ambient temperature lows.
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    Electronic ISSN: 1208-6037
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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    Population structure within the Hard Maple complex (2021)
    Canadian Science Publishing
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    Publication Date: 2021-09-01
    Description: Sugar maple (Acer saccharum Marsh.) is the most economically important member of the Hard Maple species complex, a group of related species that occupy a range between Canada and Mexico, which are adapted to distinct ecological niches. Sugar maple has been identified as vulnerable to rapid climate change, and sustainable solutions are needed to support its role in the production of maple sugar, as well as timber and nursery production in the northeastern United States. Genetic relationships among sugar maple and its allies are largely unknown. In the current study, genetic relationships of 278 individuals from six hard maple species were assessed using 17 multi-allelic microsatellite (SSR) loci. Genetic variance was partitioned into separate components for variation within and among populations and within and among species. Most of the divergence among populations (FPT = 0.263) reflected interspecific divergence (FST = 0.169), but provenances within species also differed at nontrivial scales (FPS = 0.113). Estimation and testing of paired interprovenance divergence showed that all population pairs were statistically divergent. Principal coordinates analysis indicated that the pattern of radiation observed among these taxa is broadly compatible with geography.
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    Electronic ISSN: 1208-6037
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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    Exposure of the Canadian wildland–human interface and population to wildland fire, under current and future climate conditions (2021)
    Canadian Science Publishing
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    Publication Date: 2021-09-01
    Description: In Canada, recent fire seasons have demonstrated the threat of wildland fire in the wildland–human interface (WHI) areas, where forest fuels intermingle with or abut housing, industry, and infrastructure. Although fire activity is expected to increase further in the coming decades as a result of climate change, no WHI-specific estimates of wildland fire exposure are currently available. This study combines spatial and demographic information sources to estimate the current and future wildland fire exposures, as reflected by fire return intervals (FRI) of WHI areas and populations across Canada. The WHI covers 17.3% of the forested area in Canada. Within the WHI, we found that 19.4% of the area currently experiences FRI of ≤250 years, but by the end of the century, this could increase to 28.8% under Representative Concentration Pathway (RCP) 2.6 and to 43.3% under RCP 8.5. Approximately 12.3% of the Canadian population currently live in the wildland–urban interface (WUI), which includes 32.1% of the on-reserve First Nations population. Currently, 17.8% of the on-reserve WUI population is exposed to FRI of ≤250 years, compared with only 4.7% of the remaining WUI population. By 2100, these proportions could reach 39.3% and 17.4%, respectively, under the less optimistic climatic scenarios (RCP 8.5).
    Print ISSN: 0045-5067
    Electronic ISSN: 1208-6037
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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    Positive response of tree productivity to warming is reversed by increased tree density at the Arctic tundra–taiga ecotone (2021)
    Canadian Science Publishing
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    Publication Date: 2021-09-01
    Description: The transition zone between the northern boreal forest and the Arctic tundra, known as the tundra–taiga ecotone (TTE) has undergone rapid warming in recent decades. In response to this warming, tree density, growth, and stand productivity are expected to increase. Increases in tree density have the potential to negate the positive impacts of warming on tree growth through a reduction in the active layer and an increase in competitive interactions. We assessed the effects of tree density on tree growth and climate–growth responses of Cajander larch (Larix cajanderi Mayr.) and on trends in the normalized difference vegetation index (NDVI) in the TTE of Northeast Siberia. We examined 19 mature forest stands that all established after a fire in 1940 and ranged in tree density from 300 to 37 000 stems·ha−1. High-density stands with shallow active layers had lower tree growth, higher stand productivity, and more negative growth responses to growing season temperatures compared with low-density stands with deep active layers. Variation in stand productivity across the density gradient was not captured by Landsat-derived NDVI, but NDVI did capture annual variations in stand productivity. Our results suggest that the expected increases in tree density following fires at the TTE may effectively limit tree growth and that NDVI is unlikely to capture increasing productivity associated with changes in tree density.
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    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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    Effects of soil nutrients and stand structure on aboveground net primary productivity of oak secondary forests in the forest–steppe transition zone of Loess Plateau, China (2021)
    Canadian Science Publishing
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    Publication Date: 2021-09-01
    Description: Liaodong oak (Quercus liaotungensis Koidz.) dominated forests contribute to the few natural forest ecosystems in the semiarid Loess Plateau region in China. This study investigated the influence of soil nutrients and stand structure on aboveground net primary productivity (ANPP) in the oak communities. We aimed to understand the major factors and their possible pathways that determine the ecosystem productivity. The biomass and the ANPP were estimated using plot surveys and litterfall collection in fixed plots. Linear regressions and structural equation models were used to evaluate the relationships among soil nutrients, stand structure (including vertical and horizontal structure), and ANPP. The results showed that the effect sizes of soil nutrients on ANPP and leaf production were near 60% and 70%, respectively. More than 70% of the variation in woody production was explained by stand structure, while litterfall production was largely dependent on stand vertical structure with effect size of 64%. The effect of soil nutrients on stand structural indices was detected only in the case of the vertical structure. The results suggested that soil nutrients could affect forest productivity both directly and indirectly in coordination with stand vertical structure, and that the effect of stand structure was limited in these communities.
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    Electronic ISSN: 1208-6037
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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