Tibetan alpine steppes are large and sensitive terrestrial carbon(C)reservoirs that are experiencing desertification due to global change and overgrazing,which can lead to stronger resource limitations for both above-...Tibetan alpine steppes are large and sensitive terrestrial carbon(C)reservoirs that are experiencing desertification due to global change and overgrazing,which can lead to stronger resource limitations for both above-and belowground communities.Soil nutrients,especially nitrogen(N)and phosphorus(P),are the crucial resources for plant growth and microbial metabolism.However,whether both plant and soil microbial communities in the degraded alpine steppes are limited by these soil nutrients remains unclear,which limits our understanding of the mechanisms of desertification and subsequent ecosystem restoration.Here,we evaluated potential nutrient limitations of the plant and soil microbial communities in the alpine steppe across five stages of desertification using stoichiometry-based approaches.Our results showed that soil microbial metabolism was mainly limited by C and P,and the plant N limitation and microbial C limitation were intensified while the microbial P limitation was relieved during desertification.Plant-soil-microbe interactions had significant impacts on the microbial C and P limitations,explaining 72 and 61%of the variation,respectively.Specifically,desertification ultimately affected microbial metabolic limitations by regulating soil pH,soil nutrients,and the plant N limitation.Moreover,the microbial C limitation further reduced microbial C use efficiency(CUE)with desertification,which is detrimental for organic C retention in the degraded soil.Overall,this study revealed that microbial metabolic limitations through plant-microbe interactions were the key drivers affecting soil microbial CUE,and it provided insights that can advance our knowledge of the microbial regulation of nutrient cycles and C sequestration.展开更多
Grazing exclusion using fences is a key policy being applied by the Chinese government to rehabilitate degraded grasslands on the Tibetan Plateau(TP)and elsewhere.However,there is a limited understanding of the effect...Grazing exclusion using fences is a key policy being applied by the Chinese government to rehabilitate degraded grasslands on the Tibetan Plateau(TP)and elsewhere.However,there is a limited understanding of the effects of grazing exclusion on alpine ecosystem functions and services and its impacts on herders’livelihoods.Our meta-analyses and questionnaire-based surveys revealed that grazing exclusion with fences was effective in promoting aboveground vegetation growth for up to four years in degraded alpine meadows and for up to eight years in the alpine steppes of the TP.Longer-term fencing did not bring any ecological and economic benefits.We also found that fencing hindered wildlife movement,increased grazing pressure in unfenced areas,lowered the satisfaction of herders,and rendered substantial financial costs to both regional and national governments.We recommend that traditional free grazing should be encouraged if applicable,short-term fencing(for 4-8 years)should be adopted in severely degraded grasslands,and fencing should be avoided in key wildlife habitat areas,especially the protected large mammal species.展开更多
Dominant species may strongly influence biotic conditions and interact with other species,and thus are important drivers of community dynamics and ecosystem functioning,particularly in the stressed environment of alpi...Dominant species may strongly influence biotic conditions and interact with other species,and thus are important drivers of community dynamics and ecosystem functioning,particularly in the stressed environment of alpine grasslands.However,the effects of dominant species on the community stability of different ecosystems remain poorly understood.We examined the mechanisms underlying temporal stability(2014-2020 year)of aboveground productivity and community stability in four alpine grasslands(alpine meadow,alpine meadow steppe,alpine steppe and alpine desert steppe)of the northern Tibetan with different species composition and dominance.Our results showed that community stability was significantly higher in the alpine meadow than in the other three types of grasslands.This difference was mainly attributed to the higher compensatory effect and selection effect in the alpine meadows.Furthermore,dominant species strongly affected community stability by increasing dominant species stability and species asynchrony.However,species richness had little effect on community stability.Our findings demonstrate that dominant species,as foundation species,may play leading roles in shaping community stability in the alpine grasslands,highlighting the importance of conserving dominant species for stable ecosystem functioning in these fragile ecosystems under increasing environmental fluctuations.展开更多
Asymmetric seasonal warming,characterized by more pronounced temperature increases in winter than in summer,has become a critical feature of global warming,especially in cold and high-altitude regions.Previous studies...Asymmetric seasonal warming,characterized by more pronounced temperature increases in winter than in summer,has become a critical feature of global warming,especially in cold and high-altitude regions.Previous studies have primarily focused on year-round warming,while comparatively less attention was paid to winter warming.However,a significant knowledge gap exists regarding the impacts of winter warming on ecosystem functions.To address this,we conducted an 8-year manipulated warming experiment in an alpine grassland on the Tibetan Plateau,employing three treatments:no warming,year-round warming and winter warming.We found that neither year-round warming nor winter warming significantly alters species richness at the community level.Notably,community biomass stability was maintained via species asynchrony.However,warming exerted significant effects on the plant abundance groups(dominant,common and rare species).Specifically,winter warming enhanced the stability of dominant species by increasing species asynchrony of dominant species,as the compensatory dynamics occurred between the grass and forbs.In contrast,year-round warming reduced the stability of common species,correlated with an increase in species richness and a decline in asynchrony among common species.Thus,our study underscores the capacity of alpine grassland to maintain community biomass stability via asynchrony dynamics of species under different warming conditions,although the stability of different abundance groups would be changed.Importantly,our results provide valuable insights for understanding the alpine grassland ecosystem on the Tibetan Plateau.展开更多
基金supported by the National Key Research and Development Program of China(2023YFF1304304)。
文摘Tibetan alpine steppes are large and sensitive terrestrial carbon(C)reservoirs that are experiencing desertification due to global change and overgrazing,which can lead to stronger resource limitations for both above-and belowground communities.Soil nutrients,especially nitrogen(N)and phosphorus(P),are the crucial resources for plant growth and microbial metabolism.However,whether both plant and soil microbial communities in the degraded alpine steppes are limited by these soil nutrients remains unclear,which limits our understanding of the mechanisms of desertification and subsequent ecosystem restoration.Here,we evaluated potential nutrient limitations of the plant and soil microbial communities in the alpine steppe across five stages of desertification using stoichiometry-based approaches.Our results showed that soil microbial metabolism was mainly limited by C and P,and the plant N limitation and microbial C limitation were intensified while the microbial P limitation was relieved during desertification.Plant-soil-microbe interactions had significant impacts on the microbial C and P limitations,explaining 72 and 61%of the variation,respectively.Specifically,desertification ultimately affected microbial metabolic limitations by regulating soil pH,soil nutrients,and the plant N limitation.Moreover,the microbial C limitation further reduced microbial C use efficiency(CUE)with desertification,which is detrimental for organic C retention in the degraded soil.Overall,this study revealed that microbial metabolic limitations through plant-microbe interactions were the key drivers affecting soil microbial CUE,and it provided insights that can advance our knowledge of the microbial regulation of nutrient cycles and C sequestration.
基金the Second Tibetan Plateau Scientific Expedition and Research Program(2019QZKK0405)the Science and Technology Service Network Initiative(KFJ-STS-QYZD060)+3 种基金the State Key Research Development Program of China(2016YFC0501802,2016YFC0501803 and 2016YFC0502002)the National Natural Science Foundation of China(41871040 and 41501057)the Innovative Research Team of the Ministry of Education of China(IRT_17R59)the Fundamental Research Funds for the Central Universities。
文摘Grazing exclusion using fences is a key policy being applied by the Chinese government to rehabilitate degraded grasslands on the Tibetan Plateau(TP)and elsewhere.However,there is a limited understanding of the effects of grazing exclusion on alpine ecosystem functions and services and its impacts on herders’livelihoods.Our meta-analyses and questionnaire-based surveys revealed that grazing exclusion with fences was effective in promoting aboveground vegetation growth for up to four years in degraded alpine meadows and for up to eight years in the alpine steppes of the TP.Longer-term fencing did not bring any ecological and economic benefits.We also found that fencing hindered wildlife movement,increased grazing pressure in unfenced areas,lowered the satisfaction of herders,and rendered substantial financial costs to both regional and national governments.We recommend that traditional free grazing should be encouraged if applicable,short-term fencing(for 4-8 years)should be adopted in severely degraded grasslands,and fencing should be avoided in key wildlife habitat areas,especially the protected large mammal species.
基金supported by the National Natural Science Foundation of China(31870406,42071066)the Second Tibetan Plateau Scientific Expedition and Research(STEP)program(2019QZKK0302).
文摘Dominant species may strongly influence biotic conditions and interact with other species,and thus are important drivers of community dynamics and ecosystem functioning,particularly in the stressed environment of alpine grasslands.However,the effects of dominant species on the community stability of different ecosystems remain poorly understood.We examined the mechanisms underlying temporal stability(2014-2020 year)of aboveground productivity and community stability in four alpine grasslands(alpine meadow,alpine meadow steppe,alpine steppe and alpine desert steppe)of the northern Tibetan with different species composition and dominance.Our results showed that community stability was significantly higher in the alpine meadow than in the other three types of grasslands.This difference was mainly attributed to the higher compensatory effect and selection effect in the alpine meadows.Furthermore,dominant species strongly affected community stability by increasing dominant species stability and species asynchrony.However,species richness had little effect on community stability.Our findings demonstrate that dominant species,as foundation species,may play leading roles in shaping community stability in the alpine grasslands,highlighting the importance of conserving dominant species for stable ecosystem functioning in these fragile ecosystems under increasing environmental fluctuations.
基金the National Natural Science Foundation of China(U20A2009,41991234,42077422 and 41725003)the National Key Research and Development Program of China(2022YFF1301801)the Major Science and Technology Projects in Tibet(XZ202101ZD0007G and XZ202101ZD0003N).
文摘Asymmetric seasonal warming,characterized by more pronounced temperature increases in winter than in summer,has become a critical feature of global warming,especially in cold and high-altitude regions.Previous studies have primarily focused on year-round warming,while comparatively less attention was paid to winter warming.However,a significant knowledge gap exists regarding the impacts of winter warming on ecosystem functions.To address this,we conducted an 8-year manipulated warming experiment in an alpine grassland on the Tibetan Plateau,employing three treatments:no warming,year-round warming and winter warming.We found that neither year-round warming nor winter warming significantly alters species richness at the community level.Notably,community biomass stability was maintained via species asynchrony.However,warming exerted significant effects on the plant abundance groups(dominant,common and rare species).Specifically,winter warming enhanced the stability of dominant species by increasing species asynchrony of dominant species,as the compensatory dynamics occurred between the grass and forbs.In contrast,year-round warming reduced the stability of common species,correlated with an increase in species richness and a decline in asynchrony among common species.Thus,our study underscores the capacity of alpine grassland to maintain community biomass stability via asynchrony dynamics of species under different warming conditions,although the stability of different abundance groups would be changed.Importantly,our results provide valuable insights for understanding the alpine grassland ecosystem on the Tibetan Plateau.
