Ecological stoichiometry plays an important role in revealing the mechanisms underlying biogeochemical cycles and ecosystem functions.Abiotic factors have strong effects on N-P stoichiometry,yet the impact of plant co...Ecological stoichiometry plays an important role in revealing the mechanisms underlying biogeochemical cycles and ecosystem functions.Abiotic factors have strong effects on N-P stoichiometry,yet the impact of plant community structure,especially in forests,has not been fully elucidated.We investigated 68 plots in larch forests in northern China to explore how plant community structure and environmental factors affect the N-P stoichiometry of soil and leaves.The results showed significant differences in soil and leaf N-P stoichiometry among the three larch forests,P concentration and N:P ratio of leaves were significantly related to those of soil.Except for larch forest type,N-P stoichiometry was also regulated by elevation,climatic factors,and community structure.With increasing age(from 25 to 236 years),soil N and N:P ratio significantly increased,especially in the topsoil.With increasing mean DBH,leaf N concentration and N:P ratio also increased,indicating a shift in nutrient limitations with stand growth.These findings provide evidence that plant community structure and environmental factors regulate soil and leaf N-P stoichiometry,which is critically important for understanding biogeochemical cycles and forest management undergoing natural succession.展开更多
Background:Larch(Larix Mill.)forests are widely distributed in the upper parts of mountainous areas in China,playing vital roles in constructing mountain landscapes and maintaining mountain environments.Despite their ...Background:Larch(Larix Mill.)forests are widely distributed in the upper parts of mountainous areas in China,playing vital roles in constructing mountain landscapes and maintaining mountain environments.Despite their importance,our knowledges on the large-scale patterns of structure characteristics and the relationships between different structure variables are unclear.In this paper,we investigated 155 plots from 11 natural larch forest types across the country to explore the biogeographic patterns of the structure characteristics and the allometric relationships between different structure variables for Chinese larch forests.Results:The structure characteristics were significantly different among larch forest types.For different larch forest types,the power function fits the relationships between tree height and diameter at breast height(DBH),average DBH and stem density,and taper and stem density well,but with different exponents among larch forest types.The power exponents of the allometric relationships between tree height and DBH for different larch forest types varied from 0.61 to 0.93(mean=0.86)by standard major axis regression(SMA),and from 0.51 to 0.78(mean=0.56)by ordinary least square regression(OLS).The 50%,75%and 95%quantile regression(QR)and OLS indicated that the average DBH and taper of the L.gmelinii forests,L.gmelinii var.principis-rupprechtii forests,and L.sibirica forests were significantly correlated with stem density.Conclusions:The relationship between tree height and DBH showed a power function relationship for all larch forest types in China,but with different exponents.Overall,stem density was negatively correlated with average DBH and taper.The Sect.Larix forests exhibited stand density effect.Our findings provide an important basis for recognizing the biogeographic patterns of structure factors and for the management of larch forests in China.展开更多
Shifts in tree species and their mycorrhizal associations driven by global change play key roles in biogeochemical cycles. In this paper, we proposed a framework of the mycorrhizal-associated nutrient economy(MANE), a...Shifts in tree species and their mycorrhizal associations driven by global change play key roles in biogeochemical cycles. In this paper, we proposed a framework of the mycorrhizal-associated nutrient economy(MANE), and tested it using nutrient addition experiments conducted in two tropical rainforests. We selected two tropical rainforests dominated by arbuscular mycorrhizal(AM) and ectomycorrhizal(ECM) trees, and established eighteen20 m×20 m plots in each rainforest. Six nitrogen(N) and phosphorus(P) addition treatments were randomly distributed in each rainforest with three replicates. We examined the differences in soil carbon(C) and nutrient cycling, plant and litter productivity between the two rainforests and their responses to 10-year inorganic N and P additions. We also quantified the P pools of plants, roots, litter, soil and microbes in the two rainforests. Overall,distinct MANE frameworks were applicable for tropical rainforests, in which soil C, N and P were cycled primarily in an inorganic form in the AM-dominated rainforest, whereas they were cycled in an organic form in the ECMdominated rainforest. Notably, the effects of mycorrhizal types on soil P cycling were stronger than those on C and N cycling. The intensified N and P deposition benefited the growth of AM-dominated rainforests instead of ECMdominated rainforests. Our findings underpin the key role of mycorrhizal types in regulating biogeochemical processes, and have important implications for predicting the ecological consequences of global changes.展开更多
Beta-diversity reflects the spatial changes in community species composition which helps to understand how communities are assembled and biodiversity is formed and maintained. Larch(Larix) forests, which are coniferou...Beta-diversity reflects the spatial changes in community species composition which helps to understand how communities are assembled and biodiversity is formed and maintained. Larch(Larix) forests, which are coniferous forests widely distributed in the mountainous and plateau areas in North and Southwest China, are critical for maintaining the environmental conditions and species diversity. Few studies of larch forests have examined the beta-diversity and its constituent components(species turnover and nestedness-resultant components). Here, we used 483 larch forest plots to determine the total betadiversity and its components in different life forms(i.e., tree, shrub, and herb) of larch forests in China and to evaluate the main drivers that underlie this beta-diversity. We found that total betadiversity of larch forests was mainly dependent on the species turnover component. In all life forms,total beta-diversity and the species turnover component increased with increasing geographic, elevational, current climatic, and paleoclimatic distances. In contrast, the nestedness-resultant component decreased across these same distances. Geographic and environmental factors explained 20%-25% of total beta-diversity, 18%-27% of species turnover component, and 4%-16% of nestedness-resultant component. Larch forest types significantly affected total beta-diversity and species turnover component. Taken together, our results indicate that life forms affect beta-diversity patterns of larch forests in China, and that beta-diversity is driven by both niche differentiation and dispersal limitation. Our findings help to greatly understand the mechanisms of community assemblies of larch forests in China.展开更多
Species-area relationships(SARs),also known as species-area curves,are fundamental scaling tools for biodiversity research.Sampling design and taxonomic groups affect the widely cited forms of species-area curves.Howe...Species-area relationships(SARs),also known as species-area curves,are fundamental scaling tools for biodiversity research.Sampling design and taxonomic groups affect the widely cited forms of species-area curves.However,the influence of sampling design and related environmental heterogeneity on SAR curves is rarely considered.Here,we investigated the SAR among different plant life forms(herbaceous plants,shrubs,and trees)in a 25.2-ha ForestGEO plot,the Wanglang Plot,in Sichuan,southwestern China,using a non-contiguous quadrat sampling method and power-law model.We compared the estimated parameters(the intercept c and the slope z)of the power-law models among different plant life forms,tested whether the SAR curve forms varied with sampling starting location,and assessed the effect of environmental heterogeneity accumulating with sampling area on curve variation.We found a wider range of variations in the SARs.The estimated c,z-values of power SAR were higher for the herbaceous plants than for the woody plants.A wider variation of SARs for the herbaceous plants than those for the woody plants.The selection of sampling starting location affected the SAR curve forms because of the roles of soil and topographic heterogeneity.We concluded that environmental heterogeneity regulates SAR curves sampled from different starting locations through spatial distribution of plant life forms.Thus,we recommend considering the design of sampling starting location when constructing SAR curves,especially in a heterogeneous habitat with unrandom distribution patterns of species.展开更多
Aims There are different components of carbon(C)pools in a natural forest ecosystem:biomass,soil,litter and woody debris.We asked how these pools changed with elevation in one of China’s ecologically important forest...Aims There are different components of carbon(C)pools in a natural forest ecosystem:biomass,soil,litter and woody debris.We asked how these pools changed with elevation in one of China’s ecologically important forest ecosystem,i.e.beech(Fagus L.,Fagaceae)forests,and what were the underlying driving factors of such variation.Methods The four C pools in nine beech forests were investigated along an elevational gradient(1095–1930 m)on Mt.Fanjingshan in Guizhou Province,Southwest China.Variance partitioning was used to explore the relative effects of stand age,climate and other factors on C storage.In addition,we compared the four C pools to other beech forests in Guizhou Province and worldwide.Important Findings The total C pools of beech forest ecosystems ranged from 190.5 to 504.3 Mg C ha^(–1),mainly attributed to biomass C(accounting for 33.7–73.9%)and soil C(accounting for 23.9–65.5%).No more than 4%of ecosystem C pools were stored in woody debris(0.05–3.1%)and litter(0.2–0.7%).Ecosystem C storage increased significantly with elevation,where both the biomass and woody debris C pools increased with elevation,while those of litter and soil exhibited no such trend.For the Guizhou beech forests,climate and stand age were found to be key drivers of the elevational patterns of ecosystem and biomass C storage,while for beech forests globally,stand age was the most important predictor.Compared to beech forests worldwide,beech forests in Guizhou Province displayed a relatively higher biomass C accumulation rate,which may be explained by a much higher precipitation in this area.The present study provides basic data for understanding the C budgets of Chinese beech forests and their possible roles in regional C cycling and emphasizes the general importance of stand age and climate on C accumulation.展开更多
Soil is the largest carbon(C)reservoir in terrestrial ecosystems and plays a crucial role in regulating the global C cycle and climate change.Increasing nitrogen(N)deposition has been widely considered as a critical f...Soil is the largest carbon(C)reservoir in terrestrial ecosystems and plays a crucial role in regulating the global C cycle and climate change.Increasing nitrogen(N)deposition has been widely considered as a critical factor affecting soil organic carbon(SOC)storage,but its effect on SOC components with different stability remains unclear.Here,we analyzed extensive empirical data from 304 sites worldwide to investigate how SOC and its components respond to N addition.Our analysis showed that N addition led to a significant increase in bulk SOC(6.7%),with greater increases in croplands(10.6%)and forests(6.0%)compared to grasslands(2.1%).Regarding SOC components,N addition promoted the accumulation of plant-derived C(9.7%–28.5%)over microbial-derived C(0.2%),as well as labile(5.7%)over recalcitrant components(–1.2%),resulting in a shift towards increased accumulation of plant-derived labile C.Consistently,N addition led to a greater increase in particulate organic C(11.9%)than mineral-associated organic C(3.6%),suggesting that N addition promotes C accumulation across all pools,with more increase in unstable than stable pools.The responses of SOC and its components were best predicted by the N addition rate and net primary productivity.Overall,our findings suggest that N enrichment could promote the accumulation of plant-derived and non-mineral associated C and a subsequent decrease in the overall stability of soil C pool,which underscores the importance of considering the effects of N enrichment on SOC components for a better understanding of C dynamics in soils.展开更多
China represents a significant global hotspot for species in the family Fagaceae,which are widely distributed across the country and play a crucial role in various ecological and social systems.As the global cliamte i...China represents a significant global hotspot for species in the family Fagaceae,which are widely distributed across the country and play a crucial role in various ecological and social systems.As the global cliamte is changing rapidly,predicting the future distribution and richness of these species in China holds substantial importance.This study presents the first national-scale assessment of the future distribution of 243 Fagaceae species in China,utilizing ensemble species distribution models(SDMs)for the 2050s and 2070s under various climate change scenarios.The SDM projections indicate notable changes in the distribution of Fagaceae species,characterizing with an overall decline in the distribution area,an upward migration in elevation and a northeastward shift in their range.These changes are expected to significantly alter the spatial pattern of species richness,creating possible refugia in the southwestern mountainous regions and the western Qinling Mountains.We further revealed that a considerable amount of China’s natural reserves will show decreased richness of Fagaceae under climate change.Our study systematically evaluates the impact of future climate change on the distribution of Fagaceae species in China,potentially helpful for conservation planning of these species in China.展开更多
Tropical forest soils are susceptible to acidification owing to high weathering rates and low buffering capacity.Nutrient additions,particularly nitrogen(N)and phosphorus(P)inputs,can alter soil acidity;however,their ...Tropical forest soils are susceptible to acidification owing to high weathering rates and low buffering capacity.Nutrient additions,particularly nitrogen(N)and phosphorus(P)inputs,can alter soil acidity;however,their long-term effects on the dynamics and underlying mechanisms of soil pH in tropical rainforests are not well understood.Here,we conducted two 13-year N and P fertilization experiments in primary and secondary tropical montane rainforests in Hainan,China.Results showed that long-term high-N addition reduced soil pH,and the effects increased with the rate and duration of N addition in both rainforests.The P-limited primary rainforest was more susceptible to N-induced soil acidification than the N-limited secondary rainforest with higher stand density during the experimental periods.Moreover,the depletion of base cations(primarily Ca^(2+))and the generation of exchangeable H+were the main drivers of N-induced soil acidification.However,low-and medium-N additions,single P addition,and combined N and P addition did not significantly change soil pH or cation concentrations in both forests.These findings suggest that elevated soil N availability induced by long-term fertilization may alter soil cation composition,thus leading to soil acidification and impacting ecosystem functions in tropical forests.展开更多
As one of the main food bamboo species of the giant panda(Ailuropoda melanoleuca),Fargesia denudata is widely distributed in the understory of spruce-fir forests in the mountainous area of southwestern China.However,t...As one of the main food bamboo species of the giant panda(Ailuropoda melanoleuca),Fargesia denudata is widely distributed in the understory of spruce-fir forests in the mountainous area of southwestern China.However,the driving factors of its biomass and distribution in the forests are still unclear.We conducted a systematic investigation of the tree and shrub layers(including bamboos)of 209 subplots(20 m×20 m)in a Forest Global Earth Observatory plot,the Wanglang Plot(25.2 ha),to explore the effects of abiotic(topographic and soil characteristics)and biotic(tree density,total basal area(TBA),shrub coverage,etc.)factors on the aboveground biomass of F.denudata(bamboo biomass hereafter).Bamboo biomass averaged 1.17 ton/ha,with a large variation from 0 to 4.88 ton/ha(95%confidence interval)among the 209 subplots.Bamboo biomass increased significantly with elevation,slope and mean diameter at breast height of trees,and decreased significantly with tree density,shrub coverage and soil pH.However,bamboo biomass was not significantly correlated with tree TBA,aspect,soil organic matter or total nitrogen content.The random forest model indicated that topographic factors and biotic factors had greater influences on the bamboo biomass than soil characteristics in general.Specifically,topographic factors mainly affected the bamboo biomass by changing tree density and soil characteristics.Our results can provide valuable guidance for the protection of giant pandas and the management of subalpine spruce-fir forests.展开更多
Deciduous oak forest is one of the typical vegetation types in temperate and subtropical mountain zones in China.However,the patterns and determinants of the structural characteristics of these forests remain poorly u...Deciduous oak forest is one of the typical vegetation types in temperate and subtropical mountain zones in China.However,the patterns and determinants of the structural characteristics of these forests remain poorly understood.We investigated 682 oak forest plots across China to characterize the community structures of the oak forests and analyze the underlying factors controlling their spatial patterns.Across all plots,the overall mean values were 13.7 cm,10.0 m,1468 stems/ha and 24.3 m^(2)/ha for the diameter at breast height(DBH),height,stem density and total basal area(TBA)of trees,respectively.The average species richness was 6 species/600 m^(2),10 species/100 m^(2) and 4 species/1 m^(2) for the tree,shrub and herb layers,respectively.As latitude increased,the mean tree height,stem density,TBA,tree species richness and shrub species richness decreased,and the mean DBH did not show a significant trend,while species richness of herbs increased significantly.Climatic and anthropogenic variables could explain more variations in mean DBH,mean tree height,TBA,tree species richness,shrub species richness than those in stem density and herb species richness.Further analysis showed that precipitation-related climatic factors were major factors shaping the spatial patterns of community structures.Our findings provide a basis for recognizing the biogeographic patterns of oak forest structures and their responses to global change in China.展开更多
Grasslands in the Qinghai–Tibet Plateau play an important role in preserving ecological security and high biodiversity in this region.However,the distribution of the composition and structure of plant community and t...Grasslands in the Qinghai–Tibet Plateau play an important role in preserving ecological security and high biodiversity in this region.However,the distribution of the composition and structure of plant community and the mechanism by which it maintains itself in this region are still poorly understood.Here,we designed 195 grassland plots in 39 grassland sites along an approximately 1700 m elevation gradient on the Northeastern Qinghai–Tibet Plateau.We found that the grassland community height decreased significantly with increasing elevation,whereas community coverage did not significantly change.With increasing elevation,plant species richness(αdiversity)increased significantly,but the community variability(βdiversity)decreased significantly.The constrained clustering analysis suggested that theα-andβ-diversity in the grasslands transformed gradually with elevation,and that three discontinuous points(based on community structure)were observed at elevation of 3640,4252 and 4333 m.Structural equation modeling(SEM)indicated that the increase in precipitation and the decrease in temperature significantly positively influencedαdiversity,which was negatively correlated withβdiversity.These results demonstrate a quantitative-to-qualitative change in the community composition and structure along this elevational gradient on the Qinghai–Tibet Plateau.展开更多
基金supported by the National Natural Science Foundation of China(No.32201426,No.31988102)the Major Program for Basic Research Project of Yunnan Province(No.202101BC070002)the Key Research and Development Program of Yunnan Provin ce(No.202303AC100009).
文摘Ecological stoichiometry plays an important role in revealing the mechanisms underlying biogeochemical cycles and ecosystem functions.Abiotic factors have strong effects on N-P stoichiometry,yet the impact of plant community structure,especially in forests,has not been fully elucidated.We investigated 68 plots in larch forests in northern China to explore how plant community structure and environmental factors affect the N-P stoichiometry of soil and leaves.The results showed significant differences in soil and leaf N-P stoichiometry among the three larch forests,P concentration and N:P ratio of leaves were significantly related to those of soil.Except for larch forest type,N-P stoichiometry was also regulated by elevation,climatic factors,and community structure.With increasing age(from 25 to 236 years),soil N and N:P ratio significantly increased,especially in the topsoil.With increasing mean DBH,leaf N concentration and N:P ratio also increased,indicating a shift in nutrient limitations with stand growth.These findings provide evidence that plant community structure and environmental factors regulate soil and leaf N-P stoichiometry,which is critically important for understanding biogeochemical cycles and forest management undergoing natural succession.
基金the National Science and Technology Basic Project of China(No.2015FY210200)National Natural Science Foundation(No.31988102).
文摘Background:Larch(Larix Mill.)forests are widely distributed in the upper parts of mountainous areas in China,playing vital roles in constructing mountain landscapes and maintaining mountain environments.Despite their importance,our knowledges on the large-scale patterns of structure characteristics and the relationships between different structure variables are unclear.In this paper,we investigated 155 plots from 11 natural larch forest types across the country to explore the biogeographic patterns of the structure characteristics and the allometric relationships between different structure variables for Chinese larch forests.Results:The structure characteristics were significantly different among larch forest types.For different larch forest types,the power function fits the relationships between tree height and diameter at breast height(DBH),average DBH and stem density,and taper and stem density well,but with different exponents among larch forest types.The power exponents of the allometric relationships between tree height and DBH for different larch forest types varied from 0.61 to 0.93(mean=0.86)by standard major axis regression(SMA),and from 0.51 to 0.78(mean=0.56)by ordinary least square regression(OLS).The 50%,75%and 95%quantile regression(QR)and OLS indicated that the average DBH and taper of the L.gmelinii forests,L.gmelinii var.principis-rupprechtii forests,and L.sibirica forests were significantly correlated with stem density.Conclusions:The relationship between tree height and DBH showed a power function relationship for all larch forest types in China,but with different exponents.Overall,stem density was negatively correlated with average DBH and taper.The Sect.Larix forests exhibited stand density effect.Our findings provide an important basis for recognizing the biogeographic patterns of structure factors and for the management of larch forests in China.
基金supported by the National Natural Science Foundation of China(No.31988102)National Key Research and Development Program of China(No.2017YFC0503906)。
文摘Shifts in tree species and their mycorrhizal associations driven by global change play key roles in biogeochemical cycles. In this paper, we proposed a framework of the mycorrhizal-associated nutrient economy(MANE), and tested it using nutrient addition experiments conducted in two tropical rainforests. We selected two tropical rainforests dominated by arbuscular mycorrhizal(AM) and ectomycorrhizal(ECM) trees, and established eighteen20 m×20 m plots in each rainforest. Six nitrogen(N) and phosphorus(P) addition treatments were randomly distributed in each rainforest with three replicates. We examined the differences in soil carbon(C) and nutrient cycling, plant and litter productivity between the two rainforests and their responses to 10-year inorganic N and P additions. We also quantified the P pools of plants, roots, litter, soil and microbes in the two rainforests. Overall,distinct MANE frameworks were applicable for tropical rainforests, in which soil C, N and P were cycled primarily in an inorganic form in the AM-dominated rainforest, whereas they were cycled in an organic form in the ECMdominated rainforest. Notably, the effects of mycorrhizal types on soil P cycling were stronger than those on C and N cycling. The intensified N and P deposition benefited the growth of AM-dominated rainforests instead of ECMdominated rainforests. Our findings underpin the key role of mycorrhizal types in regulating biogeochemical processes, and have important implications for predicting the ecological consequences of global changes.
基金supported by the Major Program for Basic Research Project of Yunnan Province (No. 202101BC070002)the National Natural Science Foundation of China (No. 32201426, No. 31988102)the National Science and Technology Basic Project of China (No. 2015FY210200)
文摘Beta-diversity reflects the spatial changes in community species composition which helps to understand how communities are assembled and biodiversity is formed and maintained. Larch(Larix) forests, which are coniferous forests widely distributed in the mountainous and plateau areas in North and Southwest China, are critical for maintaining the environmental conditions and species diversity. Few studies of larch forests have examined the beta-diversity and its constituent components(species turnover and nestedness-resultant components). Here, we used 483 larch forest plots to determine the total betadiversity and its components in different life forms(i.e., tree, shrub, and herb) of larch forests in China and to evaluate the main drivers that underlie this beta-diversity. We found that total betadiversity of larch forests was mainly dependent on the species turnover component. In all life forms,total beta-diversity and the species turnover component increased with increasing geographic, elevational, current climatic, and paleoclimatic distances. In contrast, the nestedness-resultant component decreased across these same distances. Geographic and environmental factors explained 20%-25% of total beta-diversity, 18%-27% of species turnover component, and 4%-16% of nestedness-resultant component. Larch forest types significantly affected total beta-diversity and species turnover component. Taken together, our results indicate that life forms affect beta-diversity patterns of larch forests in China, and that beta-diversity is driven by both niche differentiation and dispersal limitation. Our findings help to greatly understand the mechanisms of community assemblies of larch forests in China.
基金supported by the National Natural Science Foundation of China(Nos.31988102 and 31300450).
文摘Species-area relationships(SARs),also known as species-area curves,are fundamental scaling tools for biodiversity research.Sampling design and taxonomic groups affect the widely cited forms of species-area curves.However,the influence of sampling design and related environmental heterogeneity on SAR curves is rarely considered.Here,we investigated the SAR among different plant life forms(herbaceous plants,shrubs,and trees)in a 25.2-ha ForestGEO plot,the Wanglang Plot,in Sichuan,southwestern China,using a non-contiguous quadrat sampling method and power-law model.We compared the estimated parameters(the intercept c and the slope z)of the power-law models among different plant life forms,tested whether the SAR curve forms varied with sampling starting location,and assessed the effect of environmental heterogeneity accumulating with sampling area on curve variation.We found a wider range of variations in the SARs.The estimated c,z-values of power SAR were higher for the herbaceous plants than for the woody plants.A wider variation of SARs for the herbaceous plants than those for the woody plants.The selection of sampling starting location affected the SAR curve forms because of the roles of soil and topographic heterogeneity.We concluded that environmental heterogeneity regulates SAR curves sampled from different starting locations through spatial distribution of plant life forms.Thus,we recommend considering the design of sampling starting location when constructing SAR curves,especially in a heterogeneous habitat with unrandom distribution patterns of species.
基金supported by the National Key Research and Development Program of China(grant no.2017YFA0605101)Ministry of Science and Technology of China(grant no.2015FY210200)National Natural Science Foundation of China(grant nos.31700374,31621091).
文摘Aims There are different components of carbon(C)pools in a natural forest ecosystem:biomass,soil,litter and woody debris.We asked how these pools changed with elevation in one of China’s ecologically important forest ecosystem,i.e.beech(Fagus L.,Fagaceae)forests,and what were the underlying driving factors of such variation.Methods The four C pools in nine beech forests were investigated along an elevational gradient(1095–1930 m)on Mt.Fanjingshan in Guizhou Province,Southwest China.Variance partitioning was used to explore the relative effects of stand age,climate and other factors on C storage.In addition,we compared the four C pools to other beech forests in Guizhou Province and worldwide.Important Findings The total C pools of beech forest ecosystems ranged from 190.5 to 504.3 Mg C ha^(–1),mainly attributed to biomass C(accounting for 33.7–73.9%)and soil C(accounting for 23.9–65.5%).No more than 4%of ecosystem C pools were stored in woody debris(0.05–3.1%)and litter(0.2–0.7%).Ecosystem C storage increased significantly with elevation,where both the biomass and woody debris C pools increased with elevation,while those of litter and soil exhibited no such trend.For the Guizhou beech forests,climate and stand age were found to be key drivers of the elevational patterns of ecosystem and biomass C storage,while for beech forests globally,stand age was the most important predictor.Compared to beech forests worldwide,beech forests in Guizhou Province displayed a relatively higher biomass C accumulation rate,which may be explained by a much higher precipitation in this area.The present study provides basic data for understanding the C budgets of Chinese beech forests and their possible roles in regional C cycling and emphasizes the general importance of stand age and climate on C accumulation.
基金supported by the National Natural Science Foundation of China(32101331,31988102)the Key Research and Development Program of Yunnan Province(202303AC100009)Talent and Platform Program for Science and Technology(202305AA160014,202405AA350013)。
文摘Soil is the largest carbon(C)reservoir in terrestrial ecosystems and plays a crucial role in regulating the global C cycle and climate change.Increasing nitrogen(N)deposition has been widely considered as a critical factor affecting soil organic carbon(SOC)storage,but its effect on SOC components with different stability remains unclear.Here,we analyzed extensive empirical data from 304 sites worldwide to investigate how SOC and its components respond to N addition.Our analysis showed that N addition led to a significant increase in bulk SOC(6.7%),with greater increases in croplands(10.6%)and forests(6.0%)compared to grasslands(2.1%).Regarding SOC components,N addition promoted the accumulation of plant-derived C(9.7%–28.5%)over microbial-derived C(0.2%),as well as labile(5.7%)over recalcitrant components(–1.2%),resulting in a shift towards increased accumulation of plant-derived labile C.Consistently,N addition led to a greater increase in particulate organic C(11.9%)than mineral-associated organic C(3.6%),suggesting that N addition promotes C accumulation across all pools,with more increase in unstable than stable pools.The responses of SOC and its components were best predicted by the N addition rate and net primary productivity.Overall,our findings suggest that N enrichment could promote the accumulation of plant-derived and non-mineral associated C and a subsequent decrease in the overall stability of soil C pool,which underscores the importance of considering the effects of N enrichment on SOC components for a better understanding of C dynamics in soils.
基金supported by the National Natural Science Foundation of China(32271622 and 32471554)the National Key Research and Development Program of China(2022YFF0802304).
文摘China represents a significant global hotspot for species in the family Fagaceae,which are widely distributed across the country and play a crucial role in various ecological and social systems.As the global cliamte is changing rapidly,predicting the future distribution and richness of these species in China holds substantial importance.This study presents the first national-scale assessment of the future distribution of 243 Fagaceae species in China,utilizing ensemble species distribution models(SDMs)for the 2050s and 2070s under various climate change scenarios.The SDM projections indicate notable changes in the distribution of Fagaceae species,characterizing with an overall decline in the distribution area,an upward migration in elevation and a northeastward shift in their range.These changes are expected to significantly alter the spatial pattern of species richness,creating possible refugia in the southwestern mountainous regions and the western Qinling Mountains.We further revealed that a considerable amount of China’s natural reserves will show decreased richness of Fagaceae under climate change.Our study systematically evaluates the impact of future climate change on the distribution of Fagaceae species in China,potentially helpful for conservation planning of these species in China.
基金supported by the National Natural Science Foundation of China(Grant Nos.31988102,32101331).
文摘Tropical forest soils are susceptible to acidification owing to high weathering rates and low buffering capacity.Nutrient additions,particularly nitrogen(N)and phosphorus(P)inputs,can alter soil acidity;however,their long-term effects on the dynamics and underlying mechanisms of soil pH in tropical rainforests are not well understood.Here,we conducted two 13-year N and P fertilization experiments in primary and secondary tropical montane rainforests in Hainan,China.Results showed that long-term high-N addition reduced soil pH,and the effects increased with the rate and duration of N addition in both rainforests.The P-limited primary rainforest was more susceptible to N-induced soil acidification than the N-limited secondary rainforest with higher stand density during the experimental periods.Moreover,the depletion of base cations(primarily Ca^(2+))and the generation of exchangeable H+were the main drivers of N-induced soil acidification.However,low-and medium-N additions,single P addition,and combined N and P addition did not significantly change soil pH or cation concentrations in both forests.These findings suggest that elevated soil N availability induced by long-term fertilization may alter soil cation composition,thus leading to soil acidification and impacting ecosystem functions in tropical forests.
基金supported by the National Natural Science Foundation of China(31988102)the National Key Research and Development Program of China(2017YFC0503906).
文摘As one of the main food bamboo species of the giant panda(Ailuropoda melanoleuca),Fargesia denudata is widely distributed in the understory of spruce-fir forests in the mountainous area of southwestern China.However,the driving factors of its biomass and distribution in the forests are still unclear.We conducted a systematic investigation of the tree and shrub layers(including bamboos)of 209 subplots(20 m×20 m)in a Forest Global Earth Observatory plot,the Wanglang Plot(25.2 ha),to explore the effects of abiotic(topographic and soil characteristics)and biotic(tree density,total basal area(TBA),shrub coverage,etc.)factors on the aboveground biomass of F.denudata(bamboo biomass hereafter).Bamboo biomass averaged 1.17 ton/ha,with a large variation from 0 to 4.88 ton/ha(95%confidence interval)among the 209 subplots.Bamboo biomass increased significantly with elevation,slope and mean diameter at breast height of trees,and decreased significantly with tree density,shrub coverage and soil pH.However,bamboo biomass was not significantly correlated with tree TBA,aspect,soil organic matter or total nitrogen content.The random forest model indicated that topographic factors and biotic factors had greater influences on the bamboo biomass than soil characteristics in general.Specifically,topographic factors mainly affected the bamboo biomass by changing tree density and soil characteristics.Our results can provide valuable guidance for the protection of giant pandas and the management of subalpine spruce-fir forests.
基金supported by the National Natural Science Foundation of China(no.31988102)the National Key Research and Development Program of China(no.2017YFC0503906)Key Research Program of Frontier Sciences,Chinese Academy of Sciences(QYZDY-SSW-SMC011).
文摘Deciduous oak forest is one of the typical vegetation types in temperate and subtropical mountain zones in China.However,the patterns and determinants of the structural characteristics of these forests remain poorly understood.We investigated 682 oak forest plots across China to characterize the community structures of the oak forests and analyze the underlying factors controlling their spatial patterns.Across all plots,the overall mean values were 13.7 cm,10.0 m,1468 stems/ha and 24.3 m^(2)/ha for the diameter at breast height(DBH),height,stem density and total basal area(TBA)of trees,respectively.The average species richness was 6 species/600 m^(2),10 species/100 m^(2) and 4 species/1 m^(2) for the tree,shrub and herb layers,respectively.As latitude increased,the mean tree height,stem density,TBA,tree species richness and shrub species richness decreased,and the mean DBH did not show a significant trend,while species richness of herbs increased significantly.Climatic and anthropogenic variables could explain more variations in mean DBH,mean tree height,TBA,tree species richness,shrub species richness than those in stem density and herb species richness.Further analysis showed that precipitation-related climatic factors were major factors shaping the spatial patterns of community structures.Our findings provide a basis for recognizing the biogeographic patterns of oak forest structures and their responses to global change in China.
基金National Natural Science Foundation of China(31901172)Science and Technology Project of Qinghai Provincial Department of Transportation(2019-07).
文摘Grasslands in the Qinghai–Tibet Plateau play an important role in preserving ecological security and high biodiversity in this region.However,the distribution of the composition and structure of plant community and the mechanism by which it maintains itself in this region are still poorly understood.Here,we designed 195 grassland plots in 39 grassland sites along an approximately 1700 m elevation gradient on the Northeastern Qinghai–Tibet Plateau.We found that the grassland community height decreased significantly with increasing elevation,whereas community coverage did not significantly change.With increasing elevation,plant species richness(αdiversity)increased significantly,but the community variability(βdiversity)decreased significantly.The constrained clustering analysis suggested that theα-andβ-diversity in the grasslands transformed gradually with elevation,and that three discontinuous points(based on community structure)were observed at elevation of 3640,4252 and 4333 m.Structural equation modeling(SEM)indicated that the increase in precipitation and the decrease in temperature significantly positively influencedαdiversity,which was negatively correlated withβdiversity.These results demonstrate a quantitative-to-qualitative change in the community composition and structure along this elevational gradient on the Qinghai–Tibet Plateau.
