Background Global climate change has resulted in precipitation regimes exhibiting an increasing trend in rainfall intensity but a reduction in its frequency.Nitrogen(N)deposition is a crucial component of the global N...Background Global climate change has resulted in precipitation regimes exhibiting an increasing trend in rainfall intensity but a reduction in its frequency.Nitrogen(N)deposition is a crucial component of the global N cycling.Nematode body size is a trait that responds to climate change and is used as a standard trait-based indicator in soil community analysis.Variations in body size influence metabolic carbon(C).We examined the ways by which body size and metabolic C of nematodes respond to changing precipitation regimes and how N deposition regulates these responses by an 8-year manipulative experiment.Methods Nematode body size was indicated by the community-weighted mean(CWM)mass.We quantified C metabolism components of soil nematodes including production C,respiration C,and corresponding C use efficiency(CUE)under different precipitation intensities and N addition in a semi-arid steppe on the Mongolian Plateau.The Mantel test was used to determine the correlations between CWM,CUE and environmental factors.The partial least squares path modeling(PLS-PM)was conducted to quantify direct or indirect contributions among latent variables.Results We found that heavy precipitation intensity increased the CWM mass of total nematodes and omnivorespredators without N addition.N addition decreased CWM mass of bacterivores across all the precipitation intensity treatments.Stronger precipitation intensities might be favorable for nematode production and respiration C.Variations in the nematode CWM mass drove the CUE to change with N addition.Conclusions Our findings provide new insights into the mechanisms underlying nematode body size and C metabolism,and highlight that explorative studies,such as manipulative experiments,are needed to identify traits underlying size-related effects and to investigate how they affect CUE of nematodes.These efforts may increase our understanding of how changes in precipitation regimes and N deposition may alter soil nematode communities in grassland ecosystems.展开更多
A better understanding the mechanisms driving plant biomass allocation in different ecosystems is an important theoretical basis for ilustrating the adaptive strategies of plants.To date,the effects of habitat conditi...A better understanding the mechanisms driving plant biomass allocation in different ecosystems is an important theoretical basis for ilustrating the adaptive strategies of plants.To date,the effects of habitat conditions on plant biomass allocation have been widely studied.However,it is less known how plant community traits and functions(PCTF)affect biomass allocation,particularly in alpine grassland ecosystems.In this study,community-weighted means(CWM)were calculated at the community level using five leaf functional traits,and the relationships between PCTF and biomass trade-offs were explored using correlation analysis,variation partitioning analysis and structural equation modeling.We found that the trade-off values were greater than zero in both alpine meadow(AM)and alpine steppe(AS)across the Tibetan Plateau,with different values of 0.203 and 0.088 for AM and AS,respectively.Moreover,the critical factors determining biomass allocation in AS were species richness(SR;scored at 0.69)and leaf dry matter content of CWM(CWM_(LDMC),scored at 0.42),while in AM,the key factors were leaf dry matter content(CWM.pMC scored at 0.48)and leaf carbon content of CWM(CWM_(LC),scored at-0.45).In particular,both CWM_(LDMC)and SR in AS,as well as CWM_(LDMC)and CWM_(LDMC)in AM were primarily regulated by precipitation.In summary,precipitation tends to drive biomass allocation in alpine grasslands through its effects on PCTF,hence highlighting the importance of PCTF in regulating plant biomass allocation strategies along precipitation gradients.展开更多
Background:Regarding the most important ecological challenges,scientists are increasingly debating the relationship between biodiversity and ecosystem function.Despite this,several experimental and theoretical researc...Background:Regarding the most important ecological challenges,scientists are increasingly debating the relationship between biodiversity and ecosystem function.Despite this,several experimental and theoretical researches have shown inconsistencies in biodiversity and ecosystem function relationships,supporting either the niche complementarity or selection effect hypothesis.The relationship between species diversity,functional diversity,and aboveground biomass carbon was investigated in this study employing standing aboveground carbon(AGC)stock as a proxy measure for ecosystem function.We hypothesized that(i)effects of diversity on AGC can be transmitted through functional diversity and functional dominance;(ii)effects of diversity on AGC would be greater for functional dominance than functional diversity;and(iii)effects of functional diversity and functional dominance on carbon stock varied with metrics and functional traits.Community-weighted means(CWM)of functional traits(wood density,specific leaf area,and maximum plant height)were calculated to assess functional dominance(selection effects).As for functional diversity(complementarity effects),multi-trait functional diversity(selection effects)indices were computed.We tested the first hypothesis using structural equation modeling.For the second hypothesis,the effects of environmental variables such as slope,aspect,and elevation were tested first,and separate linear mixed-effects models were fitted afterward for functional diversity,functional dominance,and the two together.Results:Results revealed that slope had a significant effect on aboveground carbon storage.Functional diversity and functional dominance were significant predictors of the aboveground carbon storage(22.4%)in the dry evergreen Afromontane forest.The effects of species richness on aboveground carbon storage were mediated by functional diversity and functional dominance of species.This shows that both the selection effects and the niche complementarity are important for aboveground carbon storage prediction.However,the functional diversity effects(niche complementarity)were greater than functional dominance effects(selection effects).Conclusions:Linking diversity and biodiversity components to aboveground carbon provides better insights into the mechanisms that explain variation in aboveground carbon storage in natural forests,which may help improve the prediction of ecosystem functions.展开更多
Aims The introduction of Robinia pseudoacacia(RP)has some effects on undergrowth herbaceous plants(UH),soil properties and their relationships,which may be related to the vegetation zone.However,few studies have teste...Aims The introduction of Robinia pseudoacacia(RP)has some effects on undergrowth herbaceous plants(UH),soil properties and their relationships,which may be related to the vegetation zone.However,few studies have tested effects of RP on UH and soil over a large-scale area of the Loess Plateau.Methods The study area consisted of three vegetation zones(the steppe,forest-steppe and forest zone).Two canopy plant types were selected:RP stands and adjacent native vegetation.We measured five leaf functional traits:leaf carbon content(LC),leaf nitrogen content(LN),leaf phosphorus content(LP),specific leaf area(SLA)and leaf tissue density(LTD).The functional diversity,species diversity and community-weighted mean(CWM)traits were calculated.Important Findings(i)CWM.LN,CWM.LP and CWM.SLA increased significantly,whereas CWM.LC and CWM.LTD decreased significantly in the three vegetation zones,compared with the native communities.(ii)Species diversity,functional diversity and community biomass decreased in the steppe zone,increased in the forest zone,and did not differ significantly in the forest-steppe zone.(iii)We found only soil organic carbon(P<0.05)and soil total nitrogen(P<0.05)in the forest zone decreased significantly compared with the native plots.(iv)The relationship between UH and soil properties was affected by RP and the vegetation zone.Overall,the effect of RP on UH and soil properties was associated with the vegetation zone.This result is of great significance to the planning of restoration and reconstruction of artificial forests in the Loess Plateau.展开更多
Patterns of plant trait variation across spatial scales are important for understanding ecosystem functioning and services.However,habitat-related drivers of these patterns are poorly understood.In a conceptual model,...Patterns of plant trait variation across spatial scales are important for understanding ecosystem functioning and services.However,habitat-related drivers of these patterns are poorly understood.In a conceptual model,we ask whether and how the patterns of within-and among-site plant trait variation are driven by habitat type(terrestrial vs.wetland)across large climatic gradients.We tested these through spatial-hierarchical-sampling of leaves in herbaceous-dominated terrestrial and wetland communities within each of 26 sites across China.For all 13 plant traits,within-site variation was larger than among-site variation in both terrestrial and wetland habitats.Within-site variation was similar in most leaf traits related to carbon and nutrient economics but larger in specific leaf area and size-related traits(plant height,leaf area and thickness)in wetland compared to terrestrial habitats.Among-site variation was larger in terrestrial than wetland habitats for 10 leaf traits but smaller for plant height,leaf area and leaf nitrogen.Our results indicate the important role of local ecological processes in driving plant trait variation among coexisting species and the dependence of functional variation across habitats on traits considered.These findings will help to understand and predict the effects of climatic or land-use changes on ecosystem functioning and services.展开更多
Plant leaf litter decomposition provides a source of energy and nutrients in forest ecosystems.In addition to traditional environmental factors,the degradation process of litter is also affected by plant functional tr...Plant leaf litter decomposition provides a source of energy and nutrients in forest ecosystems.In addition to traditional environmental factors,the degradation process of litter is also affected by plant functional traits and litter quality.However,at the community level,it is still unclear whether the relative importance of plant traits and litter quality on the litter decomposition rate is consistent.A year-long mixed leaf litter decomposition experiment in a similar environment was implemented by using the litterbag method in seven typical forest types in Dongling Mountain,Beijing,North China,including six monodominant communities dominated by Juglans mandshurica,Populus cathayana,Betula dahurica,Betula platyphylla,Pinus tabuliformis and Larix gmelinii var.principis-rupprechtii and one codominant community dominated by Fraxinus rhynchophylla,Quercus mongolica and Tilia mongolica.The results showed that there were considerable differences in the litter decomposition rate(k-rate)among the different forest types.The community weighted mean(CWM)traits of green leaves and litter quality explained 35.60%and 9.05%of the k-rate variations,respectively,and the interpretation rate of their interaction was 23.37%,indicating that the CWM traits and their interaction with litter quality are the main factors affecting the k-rate variations.In the recommended daily allowance,leaf nitrogen content,leaf dry matter content,leaf tannin content and specific leaf area were the main factors affecting the k-rate variations.Therefore,we suggest that future studies should focus on the effects of the CWM traits of green leaves on litter decomposition at the community level.展开更多
Aims The mature meadows(MMs)and the swamp meadows(SMs)are the two most important ecosystems in the eastern Tibetan Plateau,China.Besides their substantial differences in terms of soil water conditions and thereby the ...Aims The mature meadows(MMs)and the swamp meadows(SMs)are the two most important ecosystems in the eastern Tibetan Plateau,China.Besides their substantial differences in terms of soil water conditions and thereby the soil oxygen and nutrients,however,little is known about the differences in community composition,struc-ture,traits and productivity between these two meadows.We par-ticularly ask whether light availability mediated by physical structure heterogeneity is a key determinant of the difference in community composition and productivity between these two meadows.Methods We examined the community structure,composition,aboveground net primary productivity(ANPP),light availability in understory and the community-weighted means(CWMs)for leaf morphological and physiological traits in 12 random plots(5 m×5 m)for each of the studied habitats.Important findings The results showed that plant community in the MM had higher variation in both vertical and horizontal structure and thus had more light availability in the understory.The MM had higher spe-cies richness and greater ANPP than the SM.The CWMs of leaf morphological and physiological traits for species in the MM fea-tured a fast-growing strategy(i.e.higher height,leaf area and net photosynthesis rate and lower nitrogen:phosphorus ratio),in con-trast to those in the SM.We also found that there were significant correlations between the CWM of traits and the ANPP,indicating that some key traits in these habitats have linked to community productivity.Our study also suggests that the heterogeneity in the community structure,which affects light availability in the under-story,may play an important role in determining the community composition and productivity.In conclusion,our study revealed significant differences in community structure,composition and traits between the MM and the SM,and the light availability that related closely to community structure is the key factor to deter-mine the composition and productivity of the community of these two habitats.展开更多
基金supported by the National Natural Science Foundation of China(NSFC-31970410)Liaoning Revitalization Talents Program(XLYC2002083)
文摘Background Global climate change has resulted in precipitation regimes exhibiting an increasing trend in rainfall intensity but a reduction in its frequency.Nitrogen(N)deposition is a crucial component of the global N cycling.Nematode body size is a trait that responds to climate change and is used as a standard trait-based indicator in soil community analysis.Variations in body size influence metabolic carbon(C).We examined the ways by which body size and metabolic C of nematodes respond to changing precipitation regimes and how N deposition regulates these responses by an 8-year manipulative experiment.Methods Nematode body size was indicated by the community-weighted mean(CWM)mass.We quantified C metabolism components of soil nematodes including production C,respiration C,and corresponding C use efficiency(CUE)under different precipitation intensities and N addition in a semi-arid steppe on the Mongolian Plateau.The Mantel test was used to determine the correlations between CWM,CUE and environmental factors.The partial least squares path modeling(PLS-PM)was conducted to quantify direct or indirect contributions among latent variables.Results We found that heavy precipitation intensity increased the CWM mass of total nematodes and omnivorespredators without N addition.N addition decreased CWM mass of bacterivores across all the precipitation intensity treatments.Stronger precipitation intensities might be favorable for nematode production and respiration C.Variations in the nematode CWM mass drove the CUE to change with N addition.Conclusions Our findings provide new insights into the mechanisms underlying nematode body size and C metabolism,and highlight that explorative studies,such as manipulative experiments,are needed to identify traits underlying size-related effects and to investigate how they affect CUE of nematodes.These efforts may increase our understanding of how changes in precipitation regimes and N deposition may alter soil nematode communities in grassland ecosystems.
基金the National Science Foundation of China(41871040)the Second Tibetan Plateau Scientific Expedition and Research(2019QZKK0405)Joint Research Project of Three-River-Resource National Park funded by the Chinese Academy of Sciences and Qinghai Provincial People's Government(LHZX-2020-08).
文摘A better understanding the mechanisms driving plant biomass allocation in different ecosystems is an important theoretical basis for ilustrating the adaptive strategies of plants.To date,the effects of habitat conditions on plant biomass allocation have been widely studied.However,it is less known how plant community traits and functions(PCTF)affect biomass allocation,particularly in alpine grassland ecosystems.In this study,community-weighted means(CWM)were calculated at the community level using five leaf functional traits,and the relationships between PCTF and biomass trade-offs were explored using correlation analysis,variation partitioning analysis and structural equation modeling.We found that the trade-off values were greater than zero in both alpine meadow(AM)and alpine steppe(AS)across the Tibetan Plateau,with different values of 0.203 and 0.088 for AM and AS,respectively.Moreover,the critical factors determining biomass allocation in AS were species richness(SR;scored at 0.69)and leaf dry matter content of CWM(CWM_(LDMC),scored at 0.42),while in AM,the key factors were leaf dry matter content(CWM.pMC scored at 0.48)and leaf carbon content of CWM(CWM_(LC),scored at-0.45).In particular,both CWM_(LDMC)and SR in AS,as well as CWM_(LDMC)and CWM_(LDMC)in AM were primarily regulated by precipitation.In summary,precipitation tends to drive biomass allocation in alpine grasslands through its effects on PCTF,hence highlighting the importance of PCTF in regulating plant biomass allocation strategies along precipitation gradients.
基金funding for this research from Oda Bultum University,Ethiopia。
文摘Background:Regarding the most important ecological challenges,scientists are increasingly debating the relationship between biodiversity and ecosystem function.Despite this,several experimental and theoretical researches have shown inconsistencies in biodiversity and ecosystem function relationships,supporting either the niche complementarity or selection effect hypothesis.The relationship between species diversity,functional diversity,and aboveground biomass carbon was investigated in this study employing standing aboveground carbon(AGC)stock as a proxy measure for ecosystem function.We hypothesized that(i)effects of diversity on AGC can be transmitted through functional diversity and functional dominance;(ii)effects of diversity on AGC would be greater for functional dominance than functional diversity;and(iii)effects of functional diversity and functional dominance on carbon stock varied with metrics and functional traits.Community-weighted means(CWM)of functional traits(wood density,specific leaf area,and maximum plant height)were calculated to assess functional dominance(selection effects).As for functional diversity(complementarity effects),multi-trait functional diversity(selection effects)indices were computed.We tested the first hypothesis using structural equation modeling.For the second hypothesis,the effects of environmental variables such as slope,aspect,and elevation were tested first,and separate linear mixed-effects models were fitted afterward for functional diversity,functional dominance,and the two together.Results:Results revealed that slope had a significant effect on aboveground carbon storage.Functional diversity and functional dominance were significant predictors of the aboveground carbon storage(22.4%)in the dry evergreen Afromontane forest.The effects of species richness on aboveground carbon storage were mediated by functional diversity and functional dominance of species.This shows that both the selection effects and the niche complementarity are important for aboveground carbon storage prediction.However,the functional diversity effects(niche complementarity)were greater than functional dominance effects(selection effects).Conclusions:Linking diversity and biodiversity components to aboveground carbon provides better insights into the mechanisms that explain variation in aboveground carbon storage in natural forests,which may help improve the prediction of ecosystem functions.
基金This study was supported by the National Natural Science Foundation of China(41671289,41601586).
文摘Aims The introduction of Robinia pseudoacacia(RP)has some effects on undergrowth herbaceous plants(UH),soil properties and their relationships,which may be related to the vegetation zone.However,few studies have tested effects of RP on UH and soil over a large-scale area of the Loess Plateau.Methods The study area consisted of three vegetation zones(the steppe,forest-steppe and forest zone).Two canopy plant types were selected:RP stands and adjacent native vegetation.We measured five leaf functional traits:leaf carbon content(LC),leaf nitrogen content(LN),leaf phosphorus content(LP),specific leaf area(SLA)and leaf tissue density(LTD).The functional diversity,species diversity and community-weighted mean(CWM)traits were calculated.Important Findings(i)CWM.LN,CWM.LP and CWM.SLA increased significantly,whereas CWM.LC and CWM.LTD decreased significantly in the three vegetation zones,compared with the native communities.(ii)Species diversity,functional diversity and community biomass decreased in the steppe zone,increased in the forest zone,and did not differ significantly in the forest-steppe zone.(iii)We found only soil organic carbon(P<0.05)and soil total nitrogen(P<0.05)in the forest zone decreased significantly compared with the native plots.(iv)The relationship between UH and soil properties was affected by RP and the vegetation zone.Overall,the effect of RP on UH and soil properties was associated with the vegetation zone.This result is of great significance to the planning of restoration and reconstruction of artificial forests in the Loess Plateau.
基金supported by the National Key Research and Development Program of China(2017YFC0506200)the National Natural Science Foundation of China(31670429,31400346,31470712,31901149)the Royal Netherlands Academy of Arts and Sciences(KNAW,CEP grant 12CDP007)。
文摘Patterns of plant trait variation across spatial scales are important for understanding ecosystem functioning and services.However,habitat-related drivers of these patterns are poorly understood.In a conceptual model,we ask whether and how the patterns of within-and among-site plant trait variation are driven by habitat type(terrestrial vs.wetland)across large climatic gradients.We tested these through spatial-hierarchical-sampling of leaves in herbaceous-dominated terrestrial and wetland communities within each of 26 sites across China.For all 13 plant traits,within-site variation was larger than among-site variation in both terrestrial and wetland habitats.Within-site variation was similar in most leaf traits related to carbon and nutrient economics but larger in specific leaf area and size-related traits(plant height,leaf area and thickness)in wetland compared to terrestrial habitats.Among-site variation was larger in terrestrial than wetland habitats for 10 leaf traits but smaller for plant height,leaf area and leaf nitrogen.Our results indicate the important role of local ecological processes in driving plant trait variation among coexisting species and the dependence of functional variation across habitats on traits considered.These findings will help to understand and predict the effects of climatic or land-use changes on ecosystem functioning and services.
基金This work was supported by the National Natural Science Foundation of China(10300-210100218).
文摘Plant leaf litter decomposition provides a source of energy and nutrients in forest ecosystems.In addition to traditional environmental factors,the degradation process of litter is also affected by plant functional traits and litter quality.However,at the community level,it is still unclear whether the relative importance of plant traits and litter quality on the litter decomposition rate is consistent.A year-long mixed leaf litter decomposition experiment in a similar environment was implemented by using the litterbag method in seven typical forest types in Dongling Mountain,Beijing,North China,including six monodominant communities dominated by Juglans mandshurica,Populus cathayana,Betula dahurica,Betula platyphylla,Pinus tabuliformis and Larix gmelinii var.principis-rupprechtii and one codominant community dominated by Fraxinus rhynchophylla,Quercus mongolica and Tilia mongolica.The results showed that there were considerable differences in the litter decomposition rate(k-rate)among the different forest types.The community weighted mean(CWM)traits of green leaves and litter quality explained 35.60%and 9.05%of the k-rate variations,respectively,and the interpretation rate of their interaction was 23.37%,indicating that the CWM traits and their interaction with litter quality are the main factors affecting the k-rate variations.In the recommended daily allowance,leaf nitrogen content,leaf dry matter content,leaf tannin content and specific leaf area were the main factors affecting the k-rate variations.Therefore,we suggest that future studies should focus on the effects of the CWM traits of green leaves on litter decomposition at the community level.
基金This work was supported by National Natural Science Foundation of China(grant No.41171214).
文摘Aims The mature meadows(MMs)and the swamp meadows(SMs)are the two most important ecosystems in the eastern Tibetan Plateau,China.Besides their substantial differences in terms of soil water conditions and thereby the soil oxygen and nutrients,however,little is known about the differences in community composition,struc-ture,traits and productivity between these two meadows.We par-ticularly ask whether light availability mediated by physical structure heterogeneity is a key determinant of the difference in community composition and productivity between these two meadows.Methods We examined the community structure,composition,aboveground net primary productivity(ANPP),light availability in understory and the community-weighted means(CWMs)for leaf morphological and physiological traits in 12 random plots(5 m×5 m)for each of the studied habitats.Important findings The results showed that plant community in the MM had higher variation in both vertical and horizontal structure and thus had more light availability in the understory.The MM had higher spe-cies richness and greater ANPP than the SM.The CWMs of leaf morphological and physiological traits for species in the MM fea-tured a fast-growing strategy(i.e.higher height,leaf area and net photosynthesis rate and lower nitrogen:phosphorus ratio),in con-trast to those in the SM.We also found that there were significant correlations between the CWM of traits and the ANPP,indicating that some key traits in these habitats have linked to community productivity.Our study also suggests that the heterogeneity in the community structure,which affects light availability in the under-story,may play an important role in determining the community composition and productivity.In conclusion,our study revealed significant differences in community structure,composition and traits between the MM and the SM,and the light availability that related closely to community structure is the key factor to deter-mine the composition and productivity of the community of these two habitats.
