Neighborhood competition is a critical driver of individual tree growth,and aboveground biomass(AGB)accumulation,which together play key roles in forest dynamics and carbon storage.Therefore,accurate biomass estimatio...Neighborhood competition is a critical driver of individual tree growth,and aboveground biomass(AGB)accumulation,which together play key roles in forest dynamics and carbon storage.Therefore,accurate biomass estimation is essential for understanding ecosystem functioning and informing forest management strategies to mitigate climate change.However,integrating neighborhood competition into biomass estimation models,particularly for young mixed forest stands,remains unexplored.In this study,we examined how incorporating neighborhood competition improves biomass prediction accuracy and how the influence of neighborhood competition differs between Scots pine(Pinus sylvestris L.)and Pyrenean oak(Quercus pyrenaica Willd.),as well as the relative contributions of intra-and interspecific competition to AGB.Our findings revealed that including neighborhood competition alongside tree size variables(DBH and total tree height)significantly improved the predictive accuracy of AGB models for Scots pine.This addition reduced the root mean square error(RMSE)by 14% and improved the model efficiency factor(MEF)by 15%.Furthermore,intraspecific competition in Scots pine slightly reduced AGB,whereas interspecific competition had a significant negative effect on AGB.In contrast,DBH alone was the best predictor of AGB for Pyrenean oak,as neighborhood competition did not improve model performance.Also,intra-and interspecific competition in Pyrenean oak had positive but nonsignificant effects on AGB.These findings highlight the important role of competition in biomass models and suggest species-specific approaches in competition dynamics to inform sustainable forest management and climate change adaptation strategies.展开更多
The resorption of nutrients by plants before litter fall and the mineralization of nutrients from plant litter by soil processes are both important pathways supporting primary productivity. While the positive relation...The resorption of nutrients by plants before litter fall and the mineralization of nutrients from plant litter by soil processes are both important pathways supporting primary productivity. While the positive relationship between plant biodiversity and primary productivity is widely accepted for natural ecosystems, the roles of nutrient resorption and mineralization in mediating that relationship remains largely unknown. Here, we quantified the relative importance of nitrogen(N) resorption and N mineralization in driving plant community N investment and the correlation between species diversity and community productivity along an N-limited successional chronosequence of the mixed broadleaved–Korean pine(Pinus koraiensis) forest in northeastern China. Leaf N resorption efficiency(NRE) at the community level increased significantly along the successional chronosequence,whereas litter N mineralization rate decreased significantly. Leaf NRE was more important than litter N mineralization rate in driving the diversity–productivity relationship. However, higher leaf NRE led to less N mineralization as succession progressed along the chronosequence. Our results highlight the importance of the N resorption pathway rather than the N mineralization pathway for forest N acquisition with community succession,and they provide mechanistic insights into the positive effects of biodiversity on ecosystem functioning. In future forest management practices, we recommend appropriate application of N fertilizer to mitigate the adverse effects of N-poor soil on seedling regeneration during late succession and thus maintain the sustainable development of temperate forest ecosystems.展开更多
Background:National and international institutions periodically demand information on forest indicators that are used for global reporting.Among other aspects,the carbon accumulated in the biomass of forest species mu...Background:National and international institutions periodically demand information on forest indicators that are used for global reporting.Among other aspects,the carbon accumulated in the biomass of forest species must be reported.For this purpose,one of the main sources of data is the National Forest Inventory(NFI),which together with statistical empirical approaches and updating procedures can even allow annual estimates of the requested indicators.Methods:Stand level biomass models,relating the dry weight of the biomass with the stand volume were developed for the five main pine species in the Iberian Peninsula(Pinus sylvestris,Pinus pinea,Pinus halepensis,Pinus nigra and Pinus pinaster).The dependence of the model on aridity and/or mean tree size was explored,as well as the importance of including the stand form factor to correct model bias.Furthermore,the capability of the models to estimate forest carbon stocks,updated for a given year,was also analysed.Results:The strong relationship between stand dry weight biomass and stand volume was modulated by the mean tree size,although the effect varied among the five pine species.Site humidity,measured using the Martonne aridity index,increased the biomass for a given volume in the cases of Pinus sylvestris,Pinus halepensis and Pinus nigra.Models that consider both mean tree size and stand form factor were more accurate and less biased than those that do not.The models developed allow carbon stocks in the main Iberian Peninsula pine forests to be estimated at stand level with biases of less than 0.2 Mg·ha^(-1).Conclusions:The results of this study reveal the importance of considering variables related with environmental conditions and stand structure when developing stand dry weight biomass models.The described methodology together with the models developed provide a precise tool that can be used for quantifying biomass and carbon stored in the Spanish pine forests in specific years when no field data are available.展开更多
Background Phosphorus(P)availability in soils regulates forest productivity.However,the drivers of soil P dynamics following forest management remain poorly understood,particularly in P-deficient forests in tropical a...Background Phosphorus(P)availability in soils regulates forest productivity.However,the drivers of soil P dynamics following forest management remain poorly understood,particularly in P-deficient forests in tropical and subtropical regions.Method Soil samples of 0–10 cm were collected from the plots after 9 years of thinning and understory removal(UR)in Pinus massoniana plantations in subtropical China.Soil physicochemical properties,microbial biomass and com-munity composition,and Hedley P fractions were measured to assess the underlying mechanisms for the dynamics of soil P fractions.Results Compared to undisturbed plots,total soil inorganic P(Pi;+24%)within the dominant species thinning(DST)plots showed a significant increase,which was associated with the accrual in resin-Pi(+30%),NaHCO3-Pi(+21%),and C.CHl-Pi(+45%).These Pi fractions were primarily correlated with increased relative abundance of Ascomycota,Rozellomycota,and Proteobacteria.Conversely,post-management(thinning and UR)assessments revealed no significant changes in total P,total organic P(Po),and residual P.The observed decrease in total Po(-9%)in DST plots was linked to reductions in NaHO-Po(-7%)and C.CHl-Po(-24%).Notably,these Po fractions were negatively affected by the relative abundance of Glomeromycota.Furthermore,variations in soil fungal and bacterial community structures accounted for 44.3%and 26.3%of the variances in soil Pi fractions,respectively,similarly explaining 20.4%and 33.3%for soil Po fractions,respectively.Conclusions These results indicate that P availability following forest management interventions within subtropi-cal pine plantations is intricately connected to microbial community composition that enhances the transformation from Po into Pi forms.展开更多
Forest productivity and carbon(C) sequestration largely depend on soil N and P availability.To date,however,the temporal variation of nutrient limitation along forest succession is still under debate.Leaf stoichiometr...Forest productivity and carbon(C) sequestration largely depend on soil N and P availability.To date,however,the temporal variation of nutrient limitation along forest succession is still under debate.Leaf stoichiometry and nutrient resorption are important indicators for predicting nutrient limitation of plant growth.Here,we measured nitrogen(N)and phosphorus(P)concentrations in green leaves and leaf liter for all woody species at four stages of temperate forest succession,and analyzed how abiotic and biotic factors affect leaf stoichiometry and nutrient resorption along forest succession.At the individual scale,leaf N and P concentrations had a significant increase at the end of the succession,while no change in leaf N:P ratio was detected.Nitrogen resorption efficiency(NRE)increased significantly with succession,but P resorption efficiency(PRE)first increased and then decreased.Significant increases in NRE:PRE ratios only occurred at the end of the succession.Moreover,plant N cycling was less responsive to soil nutrient than P cycling.At the community scale,we found that leaf N and P concentrations first decreased and then increased along forest succession,which were mainly affected by Shannon-Wiener index and species richness.Leaf N:P ratio significantly varied with succession and was mainly determined by community-weighted mean diameter at breast height(DBH).NRE increased and was significantly influenced by species richness and DBH,while PRE was relatively stable along forest succession.Thus,the NRE:PRE ratios significantly increased,indicating that N limitation is exacerbated with the temperate forest succession.These results might reflect the intense interspecific competition for limiting resource in a higher biodiversity community.In conclusion,our findings highlight the importance of biotic factors in driving forest ecosystem nutrient cycling and provide valuable information for sustainable fertilizer management practices in China's temperate and boreal forests.展开更多
The accuracy of the simulation of carbon and water processes largely relies on the selection of atmospheric forcing datasets when driving land surface models(LSM).Particularly in high-altitude regions,choosing appropr...The accuracy of the simulation of carbon and water processes largely relies on the selection of atmospheric forcing datasets when driving land surface models(LSM).Particularly in high-altitude regions,choosing appropriate atmospheric forcing datasets can effectively reduce uncertainties in the LSM simulations.Therefore,this study conducted four offline LSM simulations over the Tibetan Plateau(TP)using the Community Land Model version 4.5(CLM4.5)driven by four state-of-the-art atmospheric forcing datasets.The performances of CRUNCEP(CLM4.5 model default)and three other reanalysis-based atmospheric forcing datasets(i.e.ITPCAS,GSWP3 and WFDEI)in simulating the net primary productivity(NPP)and actual evapotranspiration(ET)were evaluated based on in situ and gridded reference datasets.Compared with in situ observations,simulated results exhibited determination coefficients(R2)ranging from 0.58 to 0.84 and 0.59 to 0.87 for observed NPP and ET,respectively,among which GSWP3 and ITPCAS showed superior performance.At the plateau level,CRUNCEP-based simulations displayed the largest bias compared with the reference NPP and ET.GSWP3-based simulations demonstrated the best performance when comprehensively considering both the magnitudes and change trends of TP-averaged NPP and ET.The simulated ET increase over the TP during 1982-2010 based on ITPCAS was significantly greater than in the other three simulations and reference ET,suggesting that ITPCAS may not be appropriate for studying long-term ET changes over the TP.These results suggest that GSWP3 is recommended for driving CLM4.5 in conducting long-term carbon and water processes simulations over the TP.This study contributes to enhancing the accuracy of LSM in water-carbon simulations over alpine regions.展开更多
Background Soil erosion affects the stability of terrestrial ecosystems and ecosystem services by directly or indirectly impacting the cycling of soil materials and energy and reducing the fertility of grassland soils...Background Soil erosion affects the stability of terrestrial ecosystems and ecosystem services by directly or indirectly impacting the cycling of soil materials and energy and reducing the fertility of grassland soils.However,research on microbial adaptation to grazing and soil erosion is limited,particularly in relation to grassland ecosystem restora-tion.Here,we assess microbial communities subjected to simulated soil erosion and grazing in a semi-arid grassland of Inner Mongolia,China.Results No significant change was observed in soil variables.However,the structure of the soil microbial commu-nity underwent significant changes as a result of soil erosion and soil erosion plus grazing,leading to a significant increase in the relative abundance of Cyanobacteria(116.80%vs 116.38%).Wind erosion and deposition contributed to an increase in the network complexity of soil bacterial and fungal communities.However,much of this effect was alleviated by grazing.Simultaneously,aeolian processes and grazing regulate soil microbial community assembly,leading to inconsistent patterns of change in bacterial and fungal communities.Under wind erosion and deposi-tion,the relative contribution of deterministic processes(4.44%vs 31.11%)in bacterial communities increased,while the relative contribution of stochastic processes(2.23%vs 20%)in fungal communities reduced.Grazing resulted in a decrease in the relative contribution of deterministic processes(8.89%)in the bacterial community and an increase in the relative contribution of stochastic processes(8.89%)in the fungal community.Conclusion This study presents a comprehensive investigation of the response of soil microbial communities to aeolian erosion–deposition and grazing in a semi-arid grassland.Our findings indicate that microbial communities in the semi-arid grassland show resistance to external disturbances and that light grazing mitigates the effects of aeo-lian erosion–deposition on microbial communities,which is essential for maintaining the stability and biodiversity of grassland ecosystems.展开更多
Aims We aimed to improve the understanding of the carbon and nutri-ent physiological responses and adaptation of semi-arid grassland plants to environmental changes.Methods We investigated plant leaf non-structural ca...Aims We aimed to improve the understanding of the carbon and nutri-ent physiological responses and adaptation of semi-arid grassland plants to environmental changes.Methods We investigated plant leaf non-structural carbohydrate(NSC=solu-ble sugars+starch),nitrogen(N)and phosphorus(P)levels in an Inner Mongolian semi-arid grassland community treated with water,N and P additions for 8 years.Two dominant grasses(Agropyron cris-tatum(L.)Gaertn.,Stipa krylovii Roshev.)and two forbs(Artemisia frigida Willd.,Potentilla bifurca L.)were analyzed.Important Findings Water addition decreased plant leaf N and P concentrations,whereas N and P addition increased them,indicating that the semi-arid grassland studied suffers from a shortage of N and P sup-ply.Both N and P addition decreased the levels of soluble sugars,starch and thus also NSC in plant leaves,which may be attributed to(i)increased carbohydrate consumption associated with a higher growth rate,and(ii)a dilution effect of greater plant size under N and P addition.Water addition tended to increase the leaf NSC levels both in the grasses(+9.2%)and forbs(+0.6%only),which may be a result of increased photosynthesis of plants with increased water availability.Under conditions of ambient and increased water supply in the present study,N addition resulted in an N/P ratio of>16 in the grasses but a significantly lower N/P ratio of<11 in the forb species.This finding implies that growth of the two grass spe-cies will be limited mainly by P availability but the forbs will still be mainly limited by N supply if N deposition,alone or in combination with summer precipitation,continues to increase as predicted in Inner Mongolia.展开更多
Aims Carbon and nutrient physiology of trees at their upper limits have been extensively studied,but those of shrubs at their upper limits have received much less attention.The aim of this study is to examine the gene...Aims Carbon and nutrient physiology of trees at their upper limits have been extensively studied,but those of shrubs at their upper limits have received much less attention.The aim of this study is to examine the general patterns of nonstructural carbohydrates(NSCs),nitrogen(N)and phosphorous(P)in shrubs at the upper limits,and to assess whether such patterns are similar to those in trees at the upper limits.Methods Across Eurasia,we measured the concentrations of soluble sugars,starch,total NSCs,N and P in leaves,branches and fine roots(<0.5 cm in diameter)of five shrub species growing at both the upper limits and lower elevations in both summer(peak growing season)and winter(dormancy season).Important Findings Neither elevation nor season had significant effects on tissue N and P concentrations,except for lower P concentrations in fine roots in winter than in summer.Total NSCs and soluble sugars in branches were significantly higher in winter than in summer.There were significant interactive effects between elevation and season for total NSCs,starch,soluble sugars and the ratio of soluble sugar to starch in fine roots,showing lower soluble sugars and starch in fine roots at the upper limits than at the lower elevations in winter but not in summer.These results suggest that the carbon physiology of roots in winter may play an important role in determining the upward distribution of shrubs,like that in the alpine tree-line trees.展开更多
Introduction:Ecosystem goods and services(EGS)studies have had little impact on policy processes and real-world decision-making due to limited understanding of the interactions and feedbacks among ecological,social an...Introduction:Ecosystem goods and services(EGS)studies have had little impact on policy processes and real-world decision-making due to limited understanding of the interactions and feedbacks among ecological,social and economic processes.Here we present an inter-and transdisciplinary analysis of global change impacts on EGS provision in a European mountain region.Our aim is to evaluate the projected influence of ecological,economic and social drivers on future EGS provision and to show possible ways to address the predominant limitations of EGS studies.Methods:The integrated findings from ecological experiments,mechanistic models of landscape dynamics,socio-economic land-use models,policy analysis and transdisciplinary stakeholder interactions are presented consecutively.Four regionally downscaled global change scenarios,for a case study region near Visp,Switzerland(350 km2),were used to examine the impacts of climate and socio-economic changes on four ecosystem services,i.e.,food provision,timber production,net greenhouse gas emissions and protection from natural hazards.Results:Our simulation results reveal four key aspects that influence the future provision of mountain EGS.First,we show the high spatial and temporal heterogeneity of EGS provision even in a small case study region.Second,we find that climate change impacts are much more pronounced for forest EGS,while changes to agricultural EGS result primarily from shifts in economic conditions.Third,our modeling results reveal the complex trade-offs associated with the different scenarios.Fourth,simulations illustrate the importance of interactions between environmental shifts and economic decisions.We discuss our simulation results with respect to both existing policy networks and transdisciplinary stakeholder interactions.Conclusion:We describe a framework based on experiments and observations that effectively supports the integration of ecological processes into an integrative modeling chain of EGS provision in mountain regions,the political decision-making process and also transdisciplinary stakeholder interactions.展开更多
基金the 2019 call for the predoctoral contract at the University of Valladolid cofinanced by Banco de Santander and projects‘CLU-2019-01-Unidad de Excelencia Instituto iuFOR’,‘PID2021-126275OB-C21’and‘PID2021-126275OB-C22’-Integrated Forest Management along complexity gradients(IMFLEX)‘MCIN/AEI/10.13039/501100011033/FEDER,UE’,which received financial support from the Regional Government of Castilla and León,Spainthe European Regional Development Fund(ERDF).
文摘Neighborhood competition is a critical driver of individual tree growth,and aboveground biomass(AGB)accumulation,which together play key roles in forest dynamics and carbon storage.Therefore,accurate biomass estimation is essential for understanding ecosystem functioning and informing forest management strategies to mitigate climate change.However,integrating neighborhood competition into biomass estimation models,particularly for young mixed forest stands,remains unexplored.In this study,we examined how incorporating neighborhood competition improves biomass prediction accuracy and how the influence of neighborhood competition differs between Scots pine(Pinus sylvestris L.)and Pyrenean oak(Quercus pyrenaica Willd.),as well as the relative contributions of intra-and interspecific competition to AGB.Our findings revealed that including neighborhood competition alongside tree size variables(DBH and total tree height)significantly improved the predictive accuracy of AGB models for Scots pine.This addition reduced the root mean square error(RMSE)by 14% and improved the model efficiency factor(MEF)by 15%.Furthermore,intraspecific competition in Scots pine slightly reduced AGB,whereas interspecific competition had a significant negative effect on AGB.In contrast,DBH alone was the best predictor of AGB for Pyrenean oak,as neighborhood competition did not improve model performance.Also,intra-and interspecific competition in Pyrenean oak had positive but nonsignificant effects on AGB.These findings highlight the important role of competition in biomass models and suggest species-specific approaches in competition dynamics to inform sustainable forest management and climate change adaptation strategies.
基金financially supported by the National Natural Science Foundation of China(No.32071533)the Fundamental Research Funds for the Central Universities,China(2572020AW13)。
文摘The resorption of nutrients by plants before litter fall and the mineralization of nutrients from plant litter by soil processes are both important pathways supporting primary productivity. While the positive relationship between plant biodiversity and primary productivity is widely accepted for natural ecosystems, the roles of nutrient resorption and mineralization in mediating that relationship remains largely unknown. Here, we quantified the relative importance of nitrogen(N) resorption and N mineralization in driving plant community N investment and the correlation between species diversity and community productivity along an N-limited successional chronosequence of the mixed broadleaved–Korean pine(Pinus koraiensis) forest in northeastern China. Leaf N resorption efficiency(NRE) at the community level increased significantly along the successional chronosequence,whereas litter N mineralization rate decreased significantly. Leaf NRE was more important than litter N mineralization rate in driving the diversity–productivity relationship. However, higher leaf NRE led to less N mineralization as succession progressed along the chronosequence. Our results highlight the importance of the N resorption pathway rather than the N mineralization pathway for forest N acquisition with community succession,and they provide mechanistic insights into the positive effects of biodiversity on ecosystem functioning. In future forest management practices, we recommend appropriate application of N fertilizer to mitigate the adverse effects of N-poor soil on seedling regeneration during late succession and thus maintain the sustainable development of temperate forest ecosystems.
文摘Background:National and international institutions periodically demand information on forest indicators that are used for global reporting.Among other aspects,the carbon accumulated in the biomass of forest species must be reported.For this purpose,one of the main sources of data is the National Forest Inventory(NFI),which together with statistical empirical approaches and updating procedures can even allow annual estimates of the requested indicators.Methods:Stand level biomass models,relating the dry weight of the biomass with the stand volume were developed for the five main pine species in the Iberian Peninsula(Pinus sylvestris,Pinus pinea,Pinus halepensis,Pinus nigra and Pinus pinaster).The dependence of the model on aridity and/or mean tree size was explored,as well as the importance of including the stand form factor to correct model bias.Furthermore,the capability of the models to estimate forest carbon stocks,updated for a given year,was also analysed.Results:The strong relationship between stand dry weight biomass and stand volume was modulated by the mean tree size,although the effect varied among the five pine species.Site humidity,measured using the Martonne aridity index,increased the biomass for a given volume in the cases of Pinus sylvestris,Pinus halepensis and Pinus nigra.Models that consider both mean tree size and stand form factor were more accurate and less biased than those that do not.The models developed allow carbon stocks in the main Iberian Peninsula pine forests to be estimated at stand level with biases of less than 0.2 Mg·ha^(-1).Conclusions:The results of this study reveal the importance of considering variables related with environmental conditions and stand structure when developing stand dry weight biomass models.The described methodology together with the models developed provide a precise tool that can be used for quantifying biomass and carbon stored in the Spanish pine forests in specific years when no field data are available.
基金supported by the National Natural Science Foundation of China(Grant Nos.32101501,32192434)
文摘Background Phosphorus(P)availability in soils regulates forest productivity.However,the drivers of soil P dynamics following forest management remain poorly understood,particularly in P-deficient forests in tropical and subtropical regions.Method Soil samples of 0–10 cm were collected from the plots after 9 years of thinning and understory removal(UR)in Pinus massoniana plantations in subtropical China.Soil physicochemical properties,microbial biomass and com-munity composition,and Hedley P fractions were measured to assess the underlying mechanisms for the dynamics of soil P fractions.Results Compared to undisturbed plots,total soil inorganic P(Pi;+24%)within the dominant species thinning(DST)plots showed a significant increase,which was associated with the accrual in resin-Pi(+30%),NaHCO3-Pi(+21%),and C.CHl-Pi(+45%).These Pi fractions were primarily correlated with increased relative abundance of Ascomycota,Rozellomycota,and Proteobacteria.Conversely,post-management(thinning and UR)assessments revealed no significant changes in total P,total organic P(Po),and residual P.The observed decrease in total Po(-9%)in DST plots was linked to reductions in NaHO-Po(-7%)and C.CHl-Po(-24%).Notably,these Po fractions were negatively affected by the relative abundance of Glomeromycota.Furthermore,variations in soil fungal and bacterial community structures accounted for 44.3%and 26.3%of the variances in soil Pi fractions,respectively,similarly explaining 20.4%and 33.3%for soil Po fractions,respectively.Conclusions These results indicate that P availability following forest management interventions within subtropi-cal pine plantations is intricately connected to microbial community composition that enhances the transformation from Po into Pi forms.
基金the National Natural Science Foundation of China(31870399,32071533)the Strategic Priority Research Program ofthe(Chinese Academy of Sciences(XDB31030000).
文摘Forest productivity and carbon(C) sequestration largely depend on soil N and P availability.To date,however,the temporal variation of nutrient limitation along forest succession is still under debate.Leaf stoichiometry and nutrient resorption are important indicators for predicting nutrient limitation of plant growth.Here,we measured nitrogen(N)and phosphorus(P)concentrations in green leaves and leaf liter for all woody species at four stages of temperate forest succession,and analyzed how abiotic and biotic factors affect leaf stoichiometry and nutrient resorption along forest succession.At the individual scale,leaf N and P concentrations had a significant increase at the end of the succession,while no change in leaf N:P ratio was detected.Nitrogen resorption efficiency(NRE)increased significantly with succession,but P resorption efficiency(PRE)first increased and then decreased.Significant increases in NRE:PRE ratios only occurred at the end of the succession.Moreover,plant N cycling was less responsive to soil nutrient than P cycling.At the community scale,we found that leaf N and P concentrations first decreased and then increased along forest succession,which were mainly affected by Shannon-Wiener index and species richness.Leaf N:P ratio significantly varied with succession and was mainly determined by community-weighted mean diameter at breast height(DBH).NRE increased and was significantly influenced by species richness and DBH,while PRE was relatively stable along forest succession.Thus,the NRE:PRE ratios significantly increased,indicating that N limitation is exacerbated with the temperate forest succession.These results might reflect the intense interspecific competition for limiting resource in a higher biodiversity community.In conclusion,our findings highlight the importance of biotic factors in driving forest ecosystem nutrient cycling and provide valuable information for sustainable fertilizer management practices in China's temperate and boreal forests.
基金supported by the National Key Research and Development Program of China(2022YFC3201702)the National Natural Science Foundation of China(42201146,U2240226)+1 种基金the Science and Technology Project of Sichuan Province(2022NSFSC1001)Fundamental Research Funds for The Central Universities(YJ2021133).
文摘The accuracy of the simulation of carbon and water processes largely relies on the selection of atmospheric forcing datasets when driving land surface models(LSM).Particularly in high-altitude regions,choosing appropriate atmospheric forcing datasets can effectively reduce uncertainties in the LSM simulations.Therefore,this study conducted four offline LSM simulations over the Tibetan Plateau(TP)using the Community Land Model version 4.5(CLM4.5)driven by four state-of-the-art atmospheric forcing datasets.The performances of CRUNCEP(CLM4.5 model default)and three other reanalysis-based atmospheric forcing datasets(i.e.ITPCAS,GSWP3 and WFDEI)in simulating the net primary productivity(NPP)and actual evapotranspiration(ET)were evaluated based on in situ and gridded reference datasets.Compared with in situ observations,simulated results exhibited determination coefficients(R2)ranging from 0.58 to 0.84 and 0.59 to 0.87 for observed NPP and ET,respectively,among which GSWP3 and ITPCAS showed superior performance.At the plateau level,CRUNCEP-based simulations displayed the largest bias compared with the reference NPP and ET.GSWP3-based simulations demonstrated the best performance when comprehensively considering both the magnitudes and change trends of TP-averaged NPP and ET.The simulated ET increase over the TP during 1982-2010 based on ITPCAS was significantly greater than in the other three simulations and reference ET,suggesting that ITPCAS may not be appropriate for studying long-term ET changes over the TP.These results suggest that GSWP3 is recommended for driving CLM4.5 in conducting long-term carbon and water processes simulations over the TP.This study contributes to enhancing the accuracy of LSM in water-carbon simulations over alpine regions.
基金financially supported by grants from the National Natural Science Foundation of China(41930643,42273084,and 41673077)Key Scientific Research Projects of Henan Province(21B180011)
文摘Background Soil erosion affects the stability of terrestrial ecosystems and ecosystem services by directly or indirectly impacting the cycling of soil materials and energy and reducing the fertility of grassland soils.However,research on microbial adaptation to grazing and soil erosion is limited,particularly in relation to grassland ecosystem restora-tion.Here,we assess microbial communities subjected to simulated soil erosion and grazing in a semi-arid grassland of Inner Mongolia,China.Results No significant change was observed in soil variables.However,the structure of the soil microbial commu-nity underwent significant changes as a result of soil erosion and soil erosion plus grazing,leading to a significant increase in the relative abundance of Cyanobacteria(116.80%vs 116.38%).Wind erosion and deposition contributed to an increase in the network complexity of soil bacterial and fungal communities.However,much of this effect was alleviated by grazing.Simultaneously,aeolian processes and grazing regulate soil microbial community assembly,leading to inconsistent patterns of change in bacterial and fungal communities.Under wind erosion and deposi-tion,the relative contribution of deterministic processes(4.44%vs 31.11%)in bacterial communities increased,while the relative contribution of stochastic processes(2.23%vs 20%)in fungal communities reduced.Grazing resulted in a decrease in the relative contribution of deterministic processes(8.89%)in the bacterial community and an increase in the relative contribution of stochastic processes(8.89%)in the fungal community.Conclusion This study presents a comprehensive investigation of the response of soil microbial communities to aeolian erosion–deposition and grazing in a semi-arid grassland.Our findings indicate that microbial communities in the semi-arid grassland show resistance to external disturbances and that light grazing mitigates the effects of aeo-lian erosion–deposition on microbial communities,which is essential for maintaining the stability and biodiversity of grassland ecosystems.
基金The National Natural Science Foundation of China(41371076,31370009)the National Key Basic Research Program of China(2011CB403204)the State Key Laboratory of Forest and Soil Ecology(LFSE2013-01).
文摘Aims We aimed to improve the understanding of the carbon and nutri-ent physiological responses and adaptation of semi-arid grassland plants to environmental changes.Methods We investigated plant leaf non-structural carbohydrate(NSC=solu-ble sugars+starch),nitrogen(N)and phosphorus(P)levels in an Inner Mongolian semi-arid grassland community treated with water,N and P additions for 8 years.Two dominant grasses(Agropyron cris-tatum(L.)Gaertn.,Stipa krylovii Roshev.)and two forbs(Artemisia frigida Willd.,Potentilla bifurca L.)were analyzed.Important Findings Water addition decreased plant leaf N and P concentrations,whereas N and P addition increased them,indicating that the semi-arid grassland studied suffers from a shortage of N and P sup-ply.Both N and P addition decreased the levels of soluble sugars,starch and thus also NSC in plant leaves,which may be attributed to(i)increased carbohydrate consumption associated with a higher growth rate,and(ii)a dilution effect of greater plant size under N and P addition.Water addition tended to increase the leaf NSC levels both in the grasses(+9.2%)and forbs(+0.6%only),which may be a result of increased photosynthesis of plants with increased water availability.Under conditions of ambient and increased water supply in the present study,N addition resulted in an N/P ratio of>16 in the grasses but a significantly lower N/P ratio of<11 in the forb species.This finding implies that growth of the two grass spe-cies will be limited mainly by P availability but the forbs will still be mainly limited by N supply if N deposition,alone or in combination with summer precipitation,continues to increase as predicted in Inner Mongolia.
基金the Natural Science Foundation of Zhejiang Province of China(LQ20C160008)Research and Innovation Initiatives of Taizhou University(2017PY033)+1 种基金Sino-Swiss Science and Technology Cooperation(SSSTC)program(EG 06-032015)the Ten Thousand Talent Program of Zhejiang Province(2018R52016).
文摘Aims Carbon and nutrient physiology of trees at their upper limits have been extensively studied,but those of shrubs at their upper limits have received much less attention.The aim of this study is to examine the general patterns of nonstructural carbohydrates(NSCs),nitrogen(N)and phosphorous(P)in shrubs at the upper limits,and to assess whether such patterns are similar to those in trees at the upper limits.Methods Across Eurasia,we measured the concentrations of soluble sugars,starch,total NSCs,N and P in leaves,branches and fine roots(<0.5 cm in diameter)of five shrub species growing at both the upper limits and lower elevations in both summer(peak growing season)and winter(dormancy season).Important Findings Neither elevation nor season had significant effects on tissue N and P concentrations,except for lower P concentrations in fine roots in winter than in summer.Total NSCs and soluble sugars in branches were significantly higher in winter than in summer.There were significant interactive effects between elevation and season for total NSCs,starch,soluble sugars and the ratio of soluble sugar to starch in fine roots,showing lower soluble sugars and starch in fine roots at the upper limits than at the lower elevations in winter but not in summer.These results suggest that the carbon physiology of roots in winter may play an important role in determining the upward distribution of shrubs,like that in the alpine tree-line trees.
基金This work was supported by the CCES(Competence Centre Environment and Sustainability of the ETH Domain,Switzerland)as part of the Mountland project.
文摘Introduction:Ecosystem goods and services(EGS)studies have had little impact on policy processes and real-world decision-making due to limited understanding of the interactions and feedbacks among ecological,social and economic processes.Here we present an inter-and transdisciplinary analysis of global change impacts on EGS provision in a European mountain region.Our aim is to evaluate the projected influence of ecological,economic and social drivers on future EGS provision and to show possible ways to address the predominant limitations of EGS studies.Methods:The integrated findings from ecological experiments,mechanistic models of landscape dynamics,socio-economic land-use models,policy analysis and transdisciplinary stakeholder interactions are presented consecutively.Four regionally downscaled global change scenarios,for a case study region near Visp,Switzerland(350 km2),were used to examine the impacts of climate and socio-economic changes on four ecosystem services,i.e.,food provision,timber production,net greenhouse gas emissions and protection from natural hazards.Results:Our simulation results reveal four key aspects that influence the future provision of mountain EGS.First,we show the high spatial and temporal heterogeneity of EGS provision even in a small case study region.Second,we find that climate change impacts are much more pronounced for forest EGS,while changes to agricultural EGS result primarily from shifts in economic conditions.Third,our modeling results reveal the complex trade-offs associated with the different scenarios.Fourth,simulations illustrate the importance of interactions between environmental shifts and economic decisions.We discuss our simulation results with respect to both existing policy networks and transdisciplinary stakeholder interactions.Conclusion:We describe a framework based on experiments and observations that effectively supports the integration of ecological processes into an integrative modeling chain of EGS provision in mountain regions,the political decision-making process and also transdisciplinary stakeholder interactions.
