Alpine ecosystems in permafrost region are extremely sensitive to climate changes.To determine spatial pattern variations in alpine meadow and alpine steppe biomass dynamics in the permafrost region of the Qinghai-Tib...Alpine ecosystems in permafrost region are extremely sensitive to climate changes.To determine spatial pattern variations in alpine meadow and alpine steppe biomass dynamics in the permafrost region of the Qinghai-Tibet Plateau,China,calibrated with historical datasets of above-ground biomass production within the permafrost region's two main ecosystems,an ecosystem-biomass model was developed by employing empirical spatialdistribution models of the study region's precipitation,air temperature and soil temperature.This model was then successfully used to simulate the spatio-temporal variations in annual alpine ecosystem biomass production under climate change.For a 0.44°C decade-1 rise in air temperature,the model predicted that the biomasses of alpine meadow and alpine steppe remained roughly the same if annual precipitation increased by 8 mm per decade-1,but the biomasses were decreased by 2.7% and 2.4%,respectively if precipitation was constant.For a 2.2°C decade-1 rise in air temperature coupled with a 12 mm decade-1 rise in precipitation,the model predicted that the biomass of alpine meadow was unchanged or slightly increased,while that of alpine steppe was increased by 5.2%.However,in the absence of any rise in precipitation,the model predicted 6.8% and 4.6% declines in alpine meadow and alpine steppe biomasses,respectively.The response of alpine steppe biomass to the rising air temperatures and precipitation was significantly lesser and greater,respectively than that of alpine meadow biomass.A better understanding of the difference in alpine ecosystem biomass production under climate change is greatly significant with respect to the influence of climate change on the carbon and water cycles in the permafrost regions of the Qinghai-Tibet Plateau.展开更多
The ecological consequences of precipitation change and increased atmospheric nitrogen(N)deposition have profound impacts on ecosystem CO2 exchange in grassland ecosystems.Water and N can largely influence grassland p...The ecological consequences of precipitation change and increased atmospheric nitrogen(N)deposition have profound impacts on ecosystem CO2 exchange in grassland ecosystems.Water and N can largely influence grassland productivity,community composition and ecosystem functions.However,the influences of water and N addition on the ecosystem CO2 exchange of alpine grassland ecosystems remain unclear.A field manipulative experiment with water and N additions was conducted in an alpine meadow on the Tibetan Plateau over 4 years with contrasting precipitation patterns.There were four treatments:control(Ctrl),N addition(N),water addition(W)and N and water addition(NW),each replicated three times.N addition,but not water addition,increased gross ecosystem productivity(GEP),plant biomass,community cover and community-weighted mean height.The responses of ecosystem CO2 exchange to water and N addition varied between the wet and dry years.Water addition had a positive effect on net ecosystem carbon exchange(NEE)due to a larger increase in GEP than in ecosystem respiration(ER)only in the dry year.On the contrary,N addition significantly enhanced ecosystem CO2 exchange only in the wet year.The increased GEP in N addition was attributed to the larger increase in NEE than ER.Moreover,N addition stimulated NEE mainly through increasing the cover of dominant species.Our observations highlight the important roles of precipitation and dominant species in regulating ecosystem CO2 exchange response to global environmental change in alpine grasslands.展开更多
基金funded by the National Basic Research Program (also called 973 Program) (Grant No.2007CB411504)the National Natural Science Foundation of China (Grant No.40925002 and No.40730634)
文摘Alpine ecosystems in permafrost region are extremely sensitive to climate changes.To determine spatial pattern variations in alpine meadow and alpine steppe biomass dynamics in the permafrost region of the Qinghai-Tibet Plateau,China,calibrated with historical datasets of above-ground biomass production within the permafrost region's two main ecosystems,an ecosystem-biomass model was developed by employing empirical spatialdistribution models of the study region's precipitation,air temperature and soil temperature.This model was then successfully used to simulate the spatio-temporal variations in annual alpine ecosystem biomass production under climate change.For a 0.44°C decade-1 rise in air temperature,the model predicted that the biomasses of alpine meadow and alpine steppe remained roughly the same if annual precipitation increased by 8 mm per decade-1,but the biomasses were decreased by 2.7% and 2.4%,respectively if precipitation was constant.For a 2.2°C decade-1 rise in air temperature coupled with a 12 mm decade-1 rise in precipitation,the model predicted that the biomass of alpine meadow was unchanged or slightly increased,while that of alpine steppe was increased by 5.2%.However,in the absence of any rise in precipitation,the model predicted 6.8% and 4.6% declines in alpine meadow and alpine steppe biomasses,respectively.The response of alpine steppe biomass to the rising air temperatures and precipitation was significantly lesser and greater,respectively than that of alpine meadow biomass.A better understanding of the difference in alpine ecosystem biomass production under climate change is greatly significant with respect to the influence of climate change on the carbon and water cycles in the permafrost regions of the Qinghai-Tibet Plateau.
基金supported by the Outstanding Youth Scientist Program of NSFC(41725003)National Key Research&Development Program of China(2017YFA0604802)+2 种基金the National Natural Science Foundation of China(41991234,42077422)the National Key Research&Development Program of China(2016YFC0501802)the Strategic Priority Research Program of Chinese Academy of Sciences(XDA20050102).
文摘The ecological consequences of precipitation change and increased atmospheric nitrogen(N)deposition have profound impacts on ecosystem CO2 exchange in grassland ecosystems.Water and N can largely influence grassland productivity,community composition and ecosystem functions.However,the influences of water and N addition on the ecosystem CO2 exchange of alpine grassland ecosystems remain unclear.A field manipulative experiment with water and N additions was conducted in an alpine meadow on the Tibetan Plateau over 4 years with contrasting precipitation patterns.There were four treatments:control(Ctrl),N addition(N),water addition(W)and N and water addition(NW),each replicated three times.N addition,but not water addition,increased gross ecosystem productivity(GEP),plant biomass,community cover and community-weighted mean height.The responses of ecosystem CO2 exchange to water and N addition varied between the wet and dry years.Water addition had a positive effect on net ecosystem carbon exchange(NEE)due to a larger increase in GEP than in ecosystem respiration(ER)only in the dry year.On the contrary,N addition significantly enhanced ecosystem CO2 exchange only in the wet year.The increased GEP in N addition was attributed to the larger increase in NEE than ER.Moreover,N addition stimulated NEE mainly through increasing the cover of dominant species.Our observations highlight the important roles of precipitation and dominant species in regulating ecosystem CO2 exchange response to global environmental change in alpine grasslands.
