Aims The aim of our research was to understand small-scale effects of topography and soil fertility on tree growth in a forest biodiversity and ecosystem functioning(BEF)experiment in subtropical SE China.Methods Geom...Aims The aim of our research was to understand small-scale effects of topography and soil fertility on tree growth in a forest biodiversity and ecosystem functioning(BEF)experiment in subtropical SE China.Methods Geomorphometric terrain analyses were carried out at a spatial resolution of 5×5 m.Soil samples of different depth increments and data on tree height were collected from a total of 566 plots(667 m2 each).The soils were analyzed for carbon(soil organic carbon[SOC]),nitrogen,acidity,cation exchange capacity(CEC),exchangeable cations and base saturation as soil fertility attributes.All plots were classified into geomorphological units.Analyses of variance and linear regressions were applied to all terrain,soil fertility and tree growth attributes.Important Findings In general,young and shallow soils and relatively small differences in stable soil properties suggest that soil erosion has truncated the soils to a large extent over the whole area of the experiment.This explains the concurrently increasing CEC and SOC stocks downslope,in hollows and in valleys.However,colluvial,carbon-rich sediments are missing widely due to the convexity of the footslopes caused by uplift and removal of eroded sediments by adjacent waterways.The results showed that soil fertility is mainly influenced by topography.Monte-Carlo flow accumulation(MCCA),curvature,slope and aspect significantly affected soil fertility.Furthermore,soil fertility was affected by the different geomorphological positions on the experimental sites with ridge and spur positions showing lower exchangeable base cation contents,especially potassium(K),due to leaching.This geomorphological effect of soil fertility is most pronounced in the topsoil and decreases when considering the subsoil down to 50 cm depth.Few soil fertility attributes affect tree height after 1-2 years of growth,among which C stocks proved to be most important while pH_(KCl)and CEC only played minor roles.Nevertheless,soil acidity and a high proportion of Al on the exchange complex affected tree height even after only 1-2 years growth.Hence,our study showed that forest nutrition is coupled to a recycling of litter nutrients,and does not only depend on subsequent supply of nutrients from the mineral soil.Besides soil fertility,topography affected tree height.We found that especially MCCA as indicator of water availability affected tree growth at small-scale,as well as aspect.Overall,our synthesis on the interrelation between fertility,topography and tree growth in a subtropical forest ecosystem in SE China showed that topographic heterogeneity lead to ecological gradients across geomorphological positions.In this respect,small-scale soil-plant interactions in a young forest can serve as a driver for the future development of vegetation and biodiversity control on soil fertility.In addition,it shows that terrain attributes should be accounted for in ecological research.展开更多
Aims We studied the influence of tree species diversity on the dynamics of coarse wood decomposition in developing forest communities in a natural,topographically heterogeneous landscape.Using the litter bag technique...Aims We studied the influence of tree species diversity on the dynamics of coarse wood decomposition in developing forest communities in a natural,topographically heterogeneous landscape.Using the litter bag technique,we investigated how and to which extent canopy tree species richness or the exclusion of mesoinvertebrates and macroinvertebrates affected wood decomposition in the light of natural variations in the microclimate.We compared the relative importance of the two aspects(experimental treatment versus microclimate)on wood decay rates using Schima superba as a standard litter.Methods Coarse woody debris(CWD)was deposited in litter bags with two different mesh sizes in a total of 134 plots along a gradient of canopy tree species richness(0-24 species).Wood decomposition was assessed at two consecutive time points,one and three years after deposition in the field.Local climatic conditions were assessed throughout the duration of the experiment.Microclimatic conditions were assessed both,directly in the field as well as indirectly via correlations with local topography.We used analysis of variance based approaches to assess the relative importance of the treatments(community tree species richness and macro invertebrate exclusion)and microclimatic conditions on wood decay.Important Findings No direct influence of tree species richness on wood decay could be detected.However,the exclusion of macroinvertebrates significantly decreased wood decomposition rates.In addition,microclimatic conditions accounted for a substantial proportion of explained variance in the observed data.Here,wood decomposition was negatively affected by low mean temperatures and high variations in local humidity and temperature.However,tree species richness as well as the respective species composition affected the presence of termites within forest communities.These,in turn,significantly increased the decay of CWD.The strength of both,experimental treatment and microclimate increased with ongoing decomposition.We conclude that,while tree species richness per se has no direct influence on wood decomposition,its influence on the local arthropod decomposer community(especially the presence of termites)does have an effect.展开更多
Aims Studies that investigate the space-filling heterogeneity of biological struc-tures in plant communities remain scarce.The main objective of this study was to evaluate the relationship between newly developed phot...Aims Studies that investigate the space-filling heterogeneity of biological struc-tures in plant communities remain scarce.The main objective of this study was to evaluate the relationship between newly developed photo-graphic measures of structural heterogeneity in digital images and plant species composition in the context of a long-term grassland experiment.Methods We tested a close-range photographic protocol using measures of structural heterogeneity in gray-tone images,namely mean infor-mation gain(MIG)and spatial anisotropy,to assess differences in the compositional(species richness)and functional characteristics(plant height and flowering)of 78 managed grassland communities.We also implemented a random placement model of community assembly to explore the links between our measures of structural complexity and the geometric pattern of plant communities.Important Findings MIG and spatial anisotropy correlated with the growth and species richness of grassland communities.Simulations showed that struc-tural heterogeneity in gray-tone digital images is a function of the size distribution and orientation pattern of plant modules.This easy,fast and non-destructive methodological approach could eventually serve to monitor the diversity and integrity of various ecosystems at different resolutions across space and time.展开更多
基金funded by the German Research Foundation(DFG FOR 891/1,2 and 3)funds from the National Natural Science Foundation of China(NSFC 30710103907,30930005,31170457 and 31210103910)+2 种基金the Swiss National Science Foundation(SNSF)financed by the Sino-German Centre for Research Promotion in Beijing(GZ 524,592,698,699 and 785)the University of Tübingen,Germany(PROMOS).
文摘Aims The aim of our research was to understand small-scale effects of topography and soil fertility on tree growth in a forest biodiversity and ecosystem functioning(BEF)experiment in subtropical SE China.Methods Geomorphometric terrain analyses were carried out at a spatial resolution of 5×5 m.Soil samples of different depth increments and data on tree height were collected from a total of 566 plots(667 m2 each).The soils were analyzed for carbon(soil organic carbon[SOC]),nitrogen,acidity,cation exchange capacity(CEC),exchangeable cations and base saturation as soil fertility attributes.All plots were classified into geomorphological units.Analyses of variance and linear regressions were applied to all terrain,soil fertility and tree growth attributes.Important Findings In general,young and shallow soils and relatively small differences in stable soil properties suggest that soil erosion has truncated the soils to a large extent over the whole area of the experiment.This explains the concurrently increasing CEC and SOC stocks downslope,in hollows and in valleys.However,colluvial,carbon-rich sediments are missing widely due to the convexity of the footslopes caused by uplift and removal of eroded sediments by adjacent waterways.The results showed that soil fertility is mainly influenced by topography.Monte-Carlo flow accumulation(MCCA),curvature,slope and aspect significantly affected soil fertility.Furthermore,soil fertility was affected by the different geomorphological positions on the experimental sites with ridge and spur positions showing lower exchangeable base cation contents,especially potassium(K),due to leaching.This geomorphological effect of soil fertility is most pronounced in the topsoil and decreases when considering the subsoil down to 50 cm depth.Few soil fertility attributes affect tree height after 1-2 years of growth,among which C stocks proved to be most important while pH_(KCl)and CEC only played minor roles.Nevertheless,soil acidity and a high proportion of Al on the exchange complex affected tree height even after only 1-2 years growth.Hence,our study showed that forest nutrition is coupled to a recycling of litter nutrients,and does not only depend on subsequent supply of nutrients from the mineral soil.Besides soil fertility,topography affected tree height.We found that especially MCCA as indicator of water availability affected tree growth at small-scale,as well as aspect.Overall,our synthesis on the interrelation between fertility,topography and tree growth in a subtropical forest ecosystem in SE China showed that topographic heterogeneity lead to ecological gradients across geomorphological positions.In this respect,small-scale soil-plant interactions in a young forest can serve as a driver for the future development of vegetation and biodiversity control on soil fertility.In addition,it shows that terrain attributes should be accounted for in ecological research.
基金the DFG for the financial support granted to the BEF-China research consortium(FOR 871).
文摘Aims We studied the influence of tree species diversity on the dynamics of coarse wood decomposition in developing forest communities in a natural,topographically heterogeneous landscape.Using the litter bag technique,we investigated how and to which extent canopy tree species richness or the exclusion of mesoinvertebrates and macroinvertebrates affected wood decomposition in the light of natural variations in the microclimate.We compared the relative importance of the two aspects(experimental treatment versus microclimate)on wood decay rates using Schima superba as a standard litter.Methods Coarse woody debris(CWD)was deposited in litter bags with two different mesh sizes in a total of 134 plots along a gradient of canopy tree species richness(0-24 species).Wood decomposition was assessed at two consecutive time points,one and three years after deposition in the field.Local climatic conditions were assessed throughout the duration of the experiment.Microclimatic conditions were assessed both,directly in the field as well as indirectly via correlations with local topography.We used analysis of variance based approaches to assess the relative importance of the treatments(community tree species richness and macro invertebrate exclusion)and microclimatic conditions on wood decay.Important Findings No direct influence of tree species richness on wood decay could be detected.However,the exclusion of macroinvertebrates significantly decreased wood decomposition rates.In addition,microclimatic conditions accounted for a substantial proportion of explained variance in the observed data.Here,wood decomposition was negatively affected by low mean temperatures and high variations in local humidity and temperature.However,tree species richness as well as the respective species composition affected the presence of termites within forest communities.These,in turn,significantly increased the decay of CWD.The strength of both,experimental treatment and microclimate increased with ongoing decomposition.We conclude that,while tree species richness per se has no direct influence on wood decomposition,its influence on the local arthropod decomposer community(especially the presence of termites)does have an effect.
基金German Research Foundation(FOR 456)Natural Sciences and Engineering Research Council of Canada(R.P.).
文摘Aims Studies that investigate the space-filling heterogeneity of biological struc-tures in plant communities remain scarce.The main objective of this study was to evaluate the relationship between newly developed photo-graphic measures of structural heterogeneity in digital images and plant species composition in the context of a long-term grassland experiment.Methods We tested a close-range photographic protocol using measures of structural heterogeneity in gray-tone images,namely mean infor-mation gain(MIG)and spatial anisotropy,to assess differences in the compositional(species richness)and functional characteristics(plant height and flowering)of 78 managed grassland communities.We also implemented a random placement model of community assembly to explore the links between our measures of structural complexity and the geometric pattern of plant communities.Important Findings MIG and spatial anisotropy correlated with the growth and species richness of grassland communities.Simulations showed that struc-tural heterogeneity in gray-tone digital images is a function of the size distribution and orientation pattern of plant modules.This easy,fast and non-destructive methodological approach could eventually serve to monitor the diversity and integrity of various ecosystems at different resolutions across space and time.
