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 The relative roles of ecological processes in structuring beta diver-sity are usually quantified by variation partitioning of beta diversity with respect to environmental and spatial variables or gamma di-versity...Aims The relative roles of ecological processes in structuring beta diver-sity are usually quantified by variation partitioning of beta diversity with respect to environmental and spatial variables or gamma di-versity.However,if important environmental or spatial factors are omitted,or a scale mismatch occurs in the analysis,unaccounted spatial correlation will appear in the residual errors and lead to re-sidual spatial correlation and problematic inferences.Methods Multi-scale ordination(MSO)partitions the canonical ordination results by distance into a set of empirical variograms which charac-terize the spatial structures of explanatory,conditional and residual variance against distance.Then these variance components can be used to diagnose residual spatial correlation by checking assump-tions related to geostatistics or regression analysis.In this paper,we first illustrate the performance of MSO using a simulated data set with known properties,thus making statistical issues explicit.We then test for significant residual spatial correlation in beta diversity analyses of the Gutianshan(GTS)24-ha subtropical forest plot in eastern China.Important Findings Even though we used up to 24 topographic and edaphic variables mapped at high resolution and spatial variables representing spa-tial structures at all scales,we still found significant residual spatial correlation at the 10 m×10 m quadrat scale.This invalidated the analysis and inferences at this scale.We also show that MSO pro-vides a complementary tool to test for significant residual spatial correlation in beta diversity analyses.Our results provided a strong argument supporting the need to test for significant residual spatial correlation before interpreting the results of beta diversity analyses.展开更多
Using the widely adopted scheme of space-for-time substitution for investigating 16 typical plots distri-buted as a pattern of contiguous grid quadrates within a sampling plot,the expressions of Shannon-Wiener index(H...Using the widely adopted scheme of space-for-time substitution for investigating 16 typical plots distri-buted as a pattern of contiguous grid quadrates within a sampling plot,the expressions of Shannon-Wiener index(H)for species diversity,Pielou index(J_(sw),J_(SI))for evenness and Simpson index(D)for ecological dominance are employed to investigate the species diversity(SD)of four evergreen broadleaved communities in the successions sequence within the Nature Reserve of the Gutian Mountains.Results showed that in the successions process from the coniferous to the mixed coniferous-broadleaved,then to Schima superba and finally to Castanopsis eyrei forest,the arbor layer SD showed the Shannon-Wiener index(H)as 1.9670,2.4975,2.6140 and 2.4356,respectively,characterized by their rise before drop and the shrub(herb)layer SD shows the maximum to be in the mixed coniferous-broadleaved(coniferous)forest(H arriving at 2.8625(1.5334)).In the vertical structure,on the other hand,for the sequenced coniferous forest,coniferous-broad mixed forest and Castnaopsis eyrei forest,the number of SD ranges in a decreasing order from the shrub,arbor to herb layer in contrast to the SD in a decreasing order of Schima superba forest ranging from the arbor to shrub and then to herb layer,and during the succession,the herb layer exhibits the maximum range of SD change among these layers,with its variation coefficients of 0.1572,0.0806,0.0899 and 0.1884 for H,J_(SW),J_(SI) and D,in order,in sharp contrast to the minimal SD range in the shrub layer,with the corresponding figures of 0.0482,0.0385,0.0142,and 0.1553.展开更多
基金National Key Research and Development Program of China(2018YFE0112800)Scientific Research Project of Baishanzu National Park(2021ZDZX01 and 2021KFLY10)National Natural Science Foundation of China(31930073 and 31901104).
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supported by the Key Research and Development Program of Zhejiang Province(No.2017C02028)the National Natural Science Foundation of China(No.31930073,31870401 and 31901104)+1 种基金the National Key Research and Development Project(2018YFE0112800)the Fundamental Research Funds for the Central Universities(2019QNA6002).
基金The analyses reported in this paper were financially supported by the National Natural Science Foundation of China(Grant No.31470490 and 31770478).
文摘Aims The relative roles of ecological processes in structuring beta diver-sity are usually quantified by variation partitioning of beta diversity with respect to environmental and spatial variables or gamma di-versity.However,if important environmental or spatial factors are omitted,or a scale mismatch occurs in the analysis,unaccounted spatial correlation will appear in the residual errors and lead to re-sidual spatial correlation and problematic inferences.Methods Multi-scale ordination(MSO)partitions the canonical ordination results by distance into a set of empirical variograms which charac-terize the spatial structures of explanatory,conditional and residual variance against distance.Then these variance components can be used to diagnose residual spatial correlation by checking assump-tions related to geostatistics or regression analysis.In this paper,we first illustrate the performance of MSO using a simulated data set with known properties,thus making statistical issues explicit.We then test for significant residual spatial correlation in beta diversity analyses of the Gutianshan(GTS)24-ha subtropical forest plot in eastern China.Important Findings Even though we used up to 24 topographic and edaphic variables mapped at high resolution and spatial variables representing spa-tial structures at all scales,we still found significant residual spatial correlation at the 10 m×10 m quadrat scale.This invalidated the analysis and inferences at this scale.We also show that MSO pro-vides a complementary tool to test for significant residual spatial correlation in beta diversity analyses.Our results provided a strong argument supporting the need to test for significant residual spatial correlation before interpreting the results of beta diversity analyses.
基金This work was supported by the Natural Sciences Foundation of China(No.30200034)Natural Science Foundation of Zhejiang Province(No.301026).
文摘Using the widely adopted scheme of space-for-time substitution for investigating 16 typical plots distri-buted as a pattern of contiguous grid quadrates within a sampling plot,the expressions of Shannon-Wiener index(H)for species diversity,Pielou index(J_(sw),J_(SI))for evenness and Simpson index(D)for ecological dominance are employed to investigate the species diversity(SD)of four evergreen broadleaved communities in the successions sequence within the Nature Reserve of the Gutian Mountains.Results showed that in the successions process from the coniferous to the mixed coniferous-broadleaved,then to Schima superba and finally to Castanopsis eyrei forest,the arbor layer SD showed the Shannon-Wiener index(H)as 1.9670,2.4975,2.6140 and 2.4356,respectively,characterized by their rise before drop and the shrub(herb)layer SD shows the maximum to be in the mixed coniferous-broadleaved(coniferous)forest(H arriving at 2.8625(1.5334)).In the vertical structure,on the other hand,for the sequenced coniferous forest,coniferous-broad mixed forest and Castnaopsis eyrei forest,the number of SD ranges in a decreasing order from the shrub,arbor to herb layer in contrast to the SD in a decreasing order of Schima superba forest ranging from the arbor to shrub and then to herb layer,and during the succession,the herb layer exhibits the maximum range of SD change among these layers,with its variation coefficients of 0.1572,0.0806,0.0899 and 0.1884 for H,J_(SW),J_(SI) and D,in order,in sharp contrast to the minimal SD range in the shrub layer,with the corresponding figures of 0.0482,0.0385,0.0142,and 0.1553.