摘要
全球气候变化背景下气温日较差(amplitude of diurnal temperature,ADT)的减小将会对高寒生态系统的碳收支产生重要影响.基于涡度相关系统观测资料,研究祁连山南麓高寒草甸2002~2016年生长季(6~9月)ADT在日、月、年尺度上对CO_(2)通量影响,为预测高寒草甸生态系统碳平衡对未来气候变化的响应具有重要参考价值.结果表明,2002~2016年的生长季中,最高气温(maximal air temperature,MaxTa)和最低气温(minimal air temperature,MinTa)呈先升高后降低的单峰变化趋势,ADT没有呈现明显的变化趋势.总初级生产力(gross primary production,GPP)和生态系统呼吸(ecosystem respiration,Re)呈先增加后降低的单峰趋势,净生态系统CO_(2)交换(net ecosystem exchange,NEE)呈先下降后上升的“V”型变化趋势.高寒草甸整个生长季总NEE、GPP和Re平均值分别为–230.4±17.3、668.8±25.5、438.3±27.5 g C m^(-2),表现为较强的碳汇.在月尺度和年尺度上,高寒草甸生长季ADT对NEE没有显著影响(P>0.05).在日尺度上,整个生长季的逐日NEE与ADT呈显著的二次曲线关系(P<0.001),阈值为19.8℃;但是,线性回归分析表明,在6~9月的日NEE与日ADT呈极显著负相关(P<0.001).整体上,仍能说明高寒草甸ADT的增大有利于生态系统的碳固持,暗示在未来气候变化背景下ADT的减小将会削弱高寒草甸生态系统的碳汇能力.
Known as the“Third Pole”and“Early-warning region”of the world,the Qinghai-Tibetan Plateau(QTP)had an intense increase in surface temperature and marked change in the amplitude of diurnal temperature(ADT),which could have significant influences on the ecosystem carbon cycle.The increasing rate of the mean daily minimum temperature(MinTa)was about two times higher than that of maximum temperature(MaxTa)in the last five decades,and this asymmetric pattern has resulted in a smaller ADT,which substantially affected the plant phenology and vegetation productivity.The reduction in the ADT caused by global climate change would have a profound impact on the carbon balance of alpine ecosystems.However,the response of carbon budgets to the ADT over the QTP remained unclear.Here,we analyzed the 15-a growing seasonal(June−September)carbon fluxes(measured by the eddy covariance[EC]technique)in alpine meadow at the southern foot of Qilian Mountains,which is one of the most extensive vegetation types on the QTP.This study aimed to clarify how carbon fluxes respond to ADT at different temporal(daily,monthly and annual)scales in alpine meadow and to understand their potential response to future climate change.The results indicated that both the MaxTa and MinTa showed bell-shaped seasonal patterns,whereas the ADT failed to show an obvious trend during the growing season from 2002 to 2016.Besides,there was a non-significant increase in annual MaxTa,MinTa and ADT(P>0.05).Meanwhile,daily gross primary productivity(GPP)and ecosystem respiration(Re)exhibited a single-peaked trend that increased and then decreased,whereas daily net ecosystem CO_(2)exchange(NEE)showed a v-shaped trend.The alpine meadow ecosystem is a carbon sink during the growing season,and the annual NEE,GPP,and Re were−230.4±17.3,668.8±25.5,438.3±27.5 g C m^(-2),respectively.Moreover,the annual GPP and Re of alpine meadow in the growing season showed a significant increase trend(P<0.05),but the annual NEE showed no significant inter-annual change trend(P>0.05).Annual CO_(2)fluxes were not related annual ADT.Only annual MaxTa exerted significant influence on variations in annual GPP and Re.Interestingly,the slopes of GPP and Re with respect to MaxTa were similar,also indicating the little impact of MaxTa on annual NEE.On a monthly scale,ADT exerted a negligible influence on CO_(2)fluxes(P>0.05),but there were significant correlations between MinTa and MaxTa with CO_(2)fluxes.On a daily scale,there was a significant quadratic relationship between daily NEE and ADT during the whole growing season(P<0.001),with a threshold of 19.8°C.However,linear regression analysis showed that there was a significant negative correlation(P<0.001)between daily NEE and daily ADT in June,July,August and September,respectively.On the whole,the increase in ADT is beneficial to carbon sequestration of the alpine meadow ecosystem.Therefore,the results suggest that the decrease in ADT in the future will cripple the carbon sink of the alpine meadow ecosystem on the Qinghai-Tibetan Plateau.
作者
祝景彬
张法伟
李红琴
杨永胜
王春雨
张光茹
罗方林
贺慧丹
李英年
Jingbin Zhu;Fawei Zhang;Hongqin Li;Yongsheng Yang;Chunyu Wang;Guangru Zhang;Fanglin Luo;Huidan He;Yingnian Li(College of Tourism,Resources and Environment,Zaozhuang University,Zaozhuang 277160,China;Northwest Institute of Plateau Biology,Chinese Academy of Sciences,Xining 810001,China;College of Life Sciences,Luoyang Normal University,Luoyang 471934,China;Key Laboratory of Adaptation and Evolution of Plateau Biota,Chinese Academy of Sciences,Xining 810001,China)
出处
《科学通报》
EI
CAS
CSCD
北大核心
2021年第1期85-95,共11页
Chinese Science Bulletin
基金
国家重点研发计划(2017YFA0604801)
青海省科技基础条件平台项目(2018-ZJ-T09)
国家自然科学基金(41877547)资助。
关键词
青藏高原
高寒草甸
日较差
CO_(2)通量
Qinghai-Tibetan Plateau
alpine meadow
amplitude of diurnal temperature
CO_(2)fluxes
