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Stein R. Moe - One of the best experts on this subject based on the ideXlab platform.
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The relative importance of vertical Soil Nutrient heterogeneity, and mean and depth-specific Soil Nutrient availabilities for tree species richness in tropical forests and woodlands.
Oecologia, 2016Co-Authors: Deo D. Shirima, Ørjan Totland, Stein R. MoeAbstract:The relative importance of resource heterogeneity and quantity on plant diversity is an ongoing debate among ecologists, but we have limited knowledge on relationships between tree diversity and heterogeneity in Soil Nutrient availability in tropical forests. We expected tree species richness to be: (1) positively related to vertical Soil Nutrient heterogeneity; (2) negatively related to mean Soil Nutrient availability; and (3) more influenced by Nutrient availability in the upper than lower Soil horizons. Using a data set from 60, 20 × 40-m plots in a moist forest, and 126 plots in miombo woodlands in Tanzania, we regressed tree species richness against vertical Soil Nutrient heterogeneity, both depth-specific (0–15, 15–30, and 30–60 cm) and mean Soil Nutrient availability, and Soil physical properties, with elevation and measures of anthropogenic disturbance as co-variables. Overall, vertical Soil Nutrient heterogeneity was the best predictor of tree species richness in miombo but, contrary to our prediction, the relationships between tree species richness and Soil Nutrient heterogeneity were negative. In the moist forest, mean Soil Nutrient availability explained considerable variations in tree species richness, and in line with our expectations, these relationships were mainly negative. Soil Nutrient availability in the top Soil layer explained more of the variation in tree species richness than that in the middle and lower layers in both vegetation types. Our study shows that vertical Soil Nutrient heterogeneity and mean availability can influence tree species richness at different magnitudes in intensively utilized tropical vegetation types.
Deo D. Shirima - One of the best experts on this subject based on the ideXlab platform.
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The relative importance of vertical Soil Nutrient heterogeneity, and mean and depth-specific Soil Nutrient availabilities for tree species richness in tropical forests and woodlands.
Oecologia, 2016Co-Authors: Deo D. Shirima, Ørjan Totland, Stein R. MoeAbstract:The relative importance of resource heterogeneity and quantity on plant diversity is an ongoing debate among ecologists, but we have limited knowledge on relationships between tree diversity and heterogeneity in Soil Nutrient availability in tropical forests. We expected tree species richness to be: (1) positively related to vertical Soil Nutrient heterogeneity; (2) negatively related to mean Soil Nutrient availability; and (3) more influenced by Nutrient availability in the upper than lower Soil horizons. Using a data set from 60, 20 × 40-m plots in a moist forest, and 126 plots in miombo woodlands in Tanzania, we regressed tree species richness against vertical Soil Nutrient heterogeneity, both depth-specific (0–15, 15–30, and 30–60 cm) and mean Soil Nutrient availability, and Soil physical properties, with elevation and measures of anthropogenic disturbance as co-variables. Overall, vertical Soil Nutrient heterogeneity was the best predictor of tree species richness in miombo but, contrary to our prediction, the relationships between tree species richness and Soil Nutrient heterogeneity were negative. In the moist forest, mean Soil Nutrient availability explained considerable variations in tree species richness, and in line with our expectations, these relationships were mainly negative. Soil Nutrient availability in the top Soil layer explained more of the variation in tree species richness than that in the middle and lower layers in both vegetation types. Our study shows that vertical Soil Nutrient heterogeneity and mean availability can influence tree species richness at different magnitudes in intensively utilized tropical vegetation types.
B P Marchant - One of the best experts on this subject based on the ideXlab platform.
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boundary line models for Soil Nutrient concentrations and wheat yield in national scale datasets
European Journal of Soil Science, 2020Co-Authors: R. M. Lark, Vincent Gillingham, David Langton, B P MarchantAbstract:In boundary line analysis a biological response (e.g., crop yield) is assumed to be a function of a variable (e.g., Soil Nutrient concentration), which limits the response in only some subset of observations because other limiting factors also apply. The response function is therefore expressed by an upper boundary of the plot of the response against the variable. This model has been used in various branches of Soil science. In this paper we apply it to the analysis of some large datasets, originating from commercial farms in England and Wales, on the recorded yield of wheat and measured concentrations of Soil Nutrients in within-field Soil management zones. We considered boundary line models for the effects of potassium (K), phosphorus (P) and magnesium (Mg) on yield, comparing the model with a simple bivariate normal distribution or a bivariate normal censored at a constant maximum yield. We were able to show, using likelihood-based methods, that the boundary line model was preferable in most cases. The boundary line model suggested that the standard RB209 Soil Nutrient index values (Agriculture and Horticulture Development Board, Nutrient management guide (RB209), 2017) are robust and apply at the within-field scale. However, there was evidence that wheat yield could respond to additional Mg at concentrations above index 0, contrary to RB209 guidelines. Furthermore, there was evidence that the boundary line model for yield and P differs between Soils at different pH and depth intervals, suggesting that shallow Soils with larger pH require a larger target P index than others. Highlights Boundary line analysis is one way to examine how Soil variables influence crop yield in large datasets.We showed that boundary line models could be applied to large datasets on Soil Nutrients and crop yield.The resulting models are consistent with current practice for P and K, but not for Mg.Models suggest that more refined recommendations for P requirement could be based on Soil pH and depth.
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Boundary line models for Soil Nutrient concentrations and wheat yield in national‐scale datasets
European journal of soil science, 2019Co-Authors: R. M. Lark, Vincent Gillingham, David Langton, B P MarchantAbstract:In boundary line analysis a biological response (e.g., crop yield) is assumed to be a function of a variable (e.g., Soil Nutrient concentration), which limits the response in only some subset of observations because other limiting factors also apply. The response function is therefore expressed by an upper boundary of the plot of the response against the variable. This model has been used in various branches of Soil science. In this paper we apply it to the analysis of some large datasets, originating from commercial farms in England and Wales, on the recorded yield of wheat and measured concentrations of Soil Nutrients in within-field Soil management zones. We considered boundary line models for the effects of potassium (K), phosphorus (P) and magnesium (Mg) on yield, comparing the model with a simple bivariate normal distribution or a bivariate normal censored at a constant maximum yield. We were able to show, using likelihood-based methods, that the boundary line model was preferable in most cases. The boundary line model suggested that the standard RB209 Soil Nutrient index values (Agriculture and Horticulture Development Board, Nutrient management guide (RB209), 2017) are robust and apply at the within-field scale. However, there was evidence that wheat yield could respond to additional Mg at concentrations above index 0, contrary to RB209 guidelines. Furthermore, there was evidence that the boundary line model for yield and P differs between Soils at different pH and depth intervals, suggesting that shallow Soils with larger pH require a larger target P index than others. Highlights Boundary line analysis is one way to examine how Soil variables influence crop yield in large datasets.We showed that boundary line models could be applied to large datasets on Soil Nutrients and crop yield.The resulting models are consistent with current practice for P and K, but not for Mg.Models suggest that more refined recommendations for P requirement could be based on Soil pH and depth.
Ørjan Totland - One of the best experts on this subject based on the ideXlab platform.
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The relative importance of vertical Soil Nutrient heterogeneity, and mean and depth-specific Soil Nutrient availabilities for tree species richness in tropical forests and woodlands.
Oecologia, 2016Co-Authors: Deo D. Shirima, Ørjan Totland, Stein R. MoeAbstract:The relative importance of resource heterogeneity and quantity on plant diversity is an ongoing debate among ecologists, but we have limited knowledge on relationships between tree diversity and heterogeneity in Soil Nutrient availability in tropical forests. We expected tree species richness to be: (1) positively related to vertical Soil Nutrient heterogeneity; (2) negatively related to mean Soil Nutrient availability; and (3) more influenced by Nutrient availability in the upper than lower Soil horizons. Using a data set from 60, 20 × 40-m plots in a moist forest, and 126 plots in miombo woodlands in Tanzania, we regressed tree species richness against vertical Soil Nutrient heterogeneity, both depth-specific (0–15, 15–30, and 30–60 cm) and mean Soil Nutrient availability, and Soil physical properties, with elevation and measures of anthropogenic disturbance as co-variables. Overall, vertical Soil Nutrient heterogeneity was the best predictor of tree species richness in miombo but, contrary to our prediction, the relationships between tree species richness and Soil Nutrient heterogeneity were negative. In the moist forest, mean Soil Nutrient availability explained considerable variations in tree species richness, and in line with our expectations, these relationships were mainly negative. Soil Nutrient availability in the top Soil layer explained more of the variation in tree species richness than that in the middle and lower layers in both vegetation types. Our study shows that vertical Soil Nutrient heterogeneity and mean availability can influence tree species richness at different magnitudes in intensively utilized tropical vegetation types.
Joan G. Ehrenfeld - One of the best experts on this subject based on the ideXlab platform.
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Effects of Exotic Plant Invasions on Soil Nutrient Cycling Processes
Ecosystems, 2003Co-Authors: Joan G. EhrenfeldAbstract:Although it is generally acknowledged that invasions by exotic plant species represent a major threat to biodiversity and ecosystem stability, little attention has been paid to the potential impacts of these invasions on Nutrient cycling processes in the Soil. The literature on plant–Soil interactions strongly suggests that the introduction of a new plant species, such as an invasive exotic, has the potential to change many components of the carbon (C), nitrogen (N), water, and other cycles of an ecosystem. I have reviewed studies that compare pool sizes and flux rates of the major Nutrient cycles in invaded and noninvaded systems for invasions of 56 species. The available data suggest that invasive plant species frequently increase biomass and net primary production, increase N availability, alter N fixation rates, and produce litter with higher decomposition rates than co-occurring natives. However, the opposite patterns also occur, and patterns of difference between exotics and native species show no trends in some other components of Nutrient cycles (for example, the size of Soil pools of C and N). In some cases, a given species has different effects at different sites, suggesting that the composition of the invaded community and/or environmental factors such as Soil type may determine the direction and magnitude of ecosystem-level impacts. Exotic plants alter Soil Nutrient dynamics by differing from native species in biomass and productivity, tissue chemistry, plant morphology, and phenology. Future research is needed to (a) experimentally test the patterns suggested by this data set; (b) examine fluxes and pools for which few data are available, including whole-site budgets; and (c) determine the magnitude of the difference in plant characteristics and in plant dominance within a community that is needed to alter ecosystem processes. Such research should be an integral component of the evaluation of the impacts of invasive species.
