Alpine meadows,alpine wetlands,and alpine desert steppes are the three typical vegetation types on the Qinghai-Tibet Plateau.The complex terrain and harsh climatic conditions across this region lead to considerable di...Alpine meadows,alpine wetlands,and alpine desert steppes are the three typical vegetation types on the Qinghai-Tibet Plateau.The complex terrain and harsh climatic conditions across this region lead to considerable diversification in the vegetation growth environment,resulting in substantial spatial heterogeneity in ecosystem carbon flux and its controlling mechanisms.Using eddy covariance data collected from March to August 2019,this study examined the responses of carbon and water fluxes in different ecosystems on the Tibetan Plateau to typical hydrometeorological factors,focusing on Net Ecosystem CO□Exchange(NEE)and Evapotranspiration(ET).The results indicate that:1)The Longbao alpine wetland primarily acted as a carbon sink from May to August,while serving as a carbon source from March to April.In the Maqin alpine meadow,it functioned as a carbon sink during June and July but acted as a carbon source in March,April,May,and August.The Tuotuohe alpine desert strppe was predominantly a net carbon sink from March to August.Overall,after the entire growing season(March to August),the Longbao alpine wetlands,Maqin alpine meadow,and Tuotuohe alpine desert steppe all showed net carbon sink properties,with net CO_(2)uptakes of 236.12 g/m^(2),291.45 g/m^(2),and 290.28 g/m^(2),respectively.2)The importance of meteorological factors to NEE varies with scale and ecosystem type,with global radiation(Rg)being the most critical factor influencing NEE variation.Volumetric soil water content(Soil_VWC)and soil temperature(Soil_T)had a positive effect on NEE at Maqin alpine meadow and Tuotuohe alpine desert steppe,while higher values of these variables showed a negative contribution.Furthermore,the sensitivity of NEE to Soil_T at Longbao alpine wetland and Tuotuohe alpine desert steppe was greater than its sensitivity to air temperature(Tair).3)The effect of Gross Primary Productivity(GPP)on NEE in alpine desert steppes is significantly greater than in alpine meadows.Both Ecosystem Respiration(Reco)and NEE were substantially limited by GPP,with 84%of GPP in alpine wetlands contributing to Reco and 16%to NEE;92%of GPP in alpine meadows contributing to Reco and 8%to NEE;and 40%of GPP in high-altitude desert grasslands contributing to Reco and 60%to NEE.4)The strong correlation between NEE and evapotranspiration suggests that water availability is the primary factor controlling changes in the carbon and water budgets of alpine ecosystems.展开更多
Enclosure is one of the most widely used management tools for degraded alpine grassland on the northern Tibetan Plateau, but the responses of different types of grassland to enclosure may vary, and research on these r...Enclosure is one of the most widely used management tools for degraded alpine grassland on the northern Tibetan Plateau, but the responses of different types of grassland to enclosure may vary, and research on these responses can provide a scientific basis for improving ecological conservation. This study took one site for each of three grassland types(alpine meadow, alpine steppe and alpine desert) on the northern Tibetan Plateau as examples, and explored the effects of enclosure on plant and soil nutrients by comparing differences in plant community biomass, leaf-soil nutrient content and their stoichiometry between samples from inside and outside the fence. The results showed that enclosure can significantly increase all aboveground biomass in these three grassland types, but it only increased the 10–20 cm underground biomass in the alpine desert. Enclosure also significantly increased the leaf nutrient content of the dominant plants and contents of total nitrogen(N), total potassium(K), and organic carbon(C) in 10–20 cm soil in alpine desert, thus changing the stoichiometry between C, N and P(phosphorus). However, enclosure significantly increased only the N content of dominant plant leaves in alpine steppe, while other nutrients and stoichiometries of both plant leaves and soil did not show significant differences in alpine meadow and alpine steppe. These results suggested that enclosure has differential effects on these three types of alpine grasslands on the northern Tibetan Plateau, and the alpine desert showed the most active ecological conservation in the responses of its soil and plant nutrients.展开更多
基金supported in part by the Fundamental Research Project of the Science and Technology Department of the Qinghai Province(Grant No.2025-ZJ-739)the National Natural Science Foundation of China(Grant No.U21A2021)+1 种基金the Open Fund of Greenhouse Gas and Carbon Neutral Key Laboratory of Qinghai Province(Grant No.ZDXM-2023-3)the Key Projects of Qinghai Meteorological Bureau(Grant No.QXZD2024-08)。
文摘Alpine meadows,alpine wetlands,and alpine desert steppes are the three typical vegetation types on the Qinghai-Tibet Plateau.The complex terrain and harsh climatic conditions across this region lead to considerable diversification in the vegetation growth environment,resulting in substantial spatial heterogeneity in ecosystem carbon flux and its controlling mechanisms.Using eddy covariance data collected from March to August 2019,this study examined the responses of carbon and water fluxes in different ecosystems on the Tibetan Plateau to typical hydrometeorological factors,focusing on Net Ecosystem CO□Exchange(NEE)and Evapotranspiration(ET).The results indicate that:1)The Longbao alpine wetland primarily acted as a carbon sink from May to August,while serving as a carbon source from March to April.In the Maqin alpine meadow,it functioned as a carbon sink during June and July but acted as a carbon source in March,April,May,and August.The Tuotuohe alpine desert strppe was predominantly a net carbon sink from March to August.Overall,after the entire growing season(March to August),the Longbao alpine wetlands,Maqin alpine meadow,and Tuotuohe alpine desert steppe all showed net carbon sink properties,with net CO_(2)uptakes of 236.12 g/m^(2),291.45 g/m^(2),and 290.28 g/m^(2),respectively.2)The importance of meteorological factors to NEE varies with scale and ecosystem type,with global radiation(Rg)being the most critical factor influencing NEE variation.Volumetric soil water content(Soil_VWC)and soil temperature(Soil_T)had a positive effect on NEE at Maqin alpine meadow and Tuotuohe alpine desert steppe,while higher values of these variables showed a negative contribution.Furthermore,the sensitivity of NEE to Soil_T at Longbao alpine wetland and Tuotuohe alpine desert steppe was greater than its sensitivity to air temperature(Tair).3)The effect of Gross Primary Productivity(GPP)on NEE in alpine desert steppes is significantly greater than in alpine meadows.Both Ecosystem Respiration(Reco)and NEE were substantially limited by GPP,with 84%of GPP in alpine wetlands contributing to Reco and 16%to NEE;92%of GPP in alpine meadows contributing to Reco and 8%to NEE;and 40%of GPP in high-altitude desert grasslands contributing to Reco and 60%to NEE.4)The strong correlation between NEE and evapotranspiration suggests that water availability is the primary factor controlling changes in the carbon and water budgets of alpine ecosystems.
基金The Strategic Priority Research Program of the Chinese Academy of Sciences(XDA19050502,XDA20010201)The National Key Research Projects of China(2017YFA0604801,2016YFC0502001)The National Natural Science Foundation of China(31770477)。
文摘Enclosure is one of the most widely used management tools for degraded alpine grassland on the northern Tibetan Plateau, but the responses of different types of grassland to enclosure may vary, and research on these responses can provide a scientific basis for improving ecological conservation. This study took one site for each of three grassland types(alpine meadow, alpine steppe and alpine desert) on the northern Tibetan Plateau as examples, and explored the effects of enclosure on plant and soil nutrients by comparing differences in plant community biomass, leaf-soil nutrient content and their stoichiometry between samples from inside and outside the fence. The results showed that enclosure can significantly increase all aboveground biomass in these three grassland types, but it only increased the 10–20 cm underground biomass in the alpine desert. Enclosure also significantly increased the leaf nutrient content of the dominant plants and contents of total nitrogen(N), total potassium(K), and organic carbon(C) in 10–20 cm soil in alpine desert, thus changing the stoichiometry between C, N and P(phosphorus). However, enclosure significantly increased only the N content of dominant plant leaves in alpine steppe, while other nutrients and stoichiometries of both plant leaves and soil did not show significant differences in alpine meadow and alpine steppe. These results suggested that enclosure has differential effects on these three types of alpine grasslands on the northern Tibetan Plateau, and the alpine desert showed the most active ecological conservation in the responses of its soil and plant nutrients.
