藏北高寒草地植被降水利用效率对增温的响应  

Response of vegetation precipitation use efficiency to experimental warming in alpine grasslands of northern Tibet

作　　者：孙维[1] 齐虎啸 付刚[1] SUN Wei;QI Huxiao;FU Gang(Lhasa Plateau Ecosystem Research Station,Key Laboratory of Ecosystem Network Observation and Modeling,Institute of Geographic Sciences and Natural Resources Research,Chinese Academy of Sciences,Beijing 100101,China;University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]中国科学院地理科学与资源研究所生态系统网络观测与模拟重点实验室拉萨高原生态系统研究站,北京100101 [2]中国科学院大学,北京100049

出　　处：《草业科学》2022年第6期1069-1079,共11页Pratacultural Science

基　　金：中国科学院青年创新促进会会员(2020054);国家重点研发项目(2017YFA0604801);中国科学院地理科学与资源研究所秉维优秀青年人才(2018RC202);国家自然科学基金(31600432);西藏自治区饲草专项(XZ202101ZD0003N);仲巴县农业绿色发展先行先试支撑体系固定观测试验站建设。

摘　　要：植被降水利用效率(PUE)是量化陆地生态系统碳水耦合机制的一个关键指标,然而气候变暖如何影响青藏高原高寒草地生态系统的植被降水利用效率仍不清楚。2010年在藏北高原3个海拔(4313、4513和4693 m)上布设了增温试验平台,采用开顶式增温箱模拟气候变暖。利用农业多光谱相机获得了2014–2015年和2017–2018年植被的归一化植被指数(NDVI)和土壤调节植被指数(SAVI),并利用观测的NDVI计算了地上生物量(AGB)。利用微气候观测系统对土壤温度、土壤湿度、空气温度和相对湿度进行了观测,并计算了饱和水汽压差。结果表明:试验增温极显著(P<0.001)增加了空气温度(Ta)、土壤温度(Ts)和饱和水汽压差(VPD),而对AGB、NDVI和SAVI无显著影响(P>0.05)。试验增温显著(P<0.05)降低了海拔4313 m 4年平均的植被降水利用效率,即导致了相对干旱年份的植被降水利用效率的显著(P<0.05)减少,而对相对湿润年份的植被降水利用效率无显著影响(P>0.05)。试验增温没有显著改变海拔4513和4693 m的植被降水利用效率。总体而言,试验增温增加了3个海拔间的植被降水利用效率的差异。因此,藏北高寒草地生态系统的植被降水利用效率的温度敏感性随着海拔和观测年份的变化而变化;且气候变暖重构了藏北高原高寒草地生态系统的植被降水利用效率的海拔分布格局,即气候变暖增强了藏北不同海拔的高寒草地生态系统的植被降水利用效率的异质性。Vegetation precipitation use efficiency is a key indicator for quantifying the carbon-water coupling mechanism in terrestrial ecosystems.However,it remains unclear how climate warming will affect the vegetation precipitation use efficiency of alpine grassland ecosystems on the Tibetan Plateau.A field warming experiment was performed in three alpine grassland sites(located at elevations 4313,4513,and 4693 m)in northern Tibet in 2010.Open-top chambers were used to simulate climate warming.The normalized difference vegetation index(NDVI)and soil-adjusted vegetation index(SAVI)were measured using an agricultural camera,and then aboveground biomass(AGB)was modelled using the measured NDVI in 2014-2015 and 2017-2018.The soil temperature,soil moisture,air temperature,and relative humidity were measured using microclimate stations.The vapor pressure deficit was calculated using the measured air temperature and relative humidity.Experimental warming significantly(P<0.001)increased air temperature(Ta),soil temperature(Ts),and vapor pressure deficit(VPD)but had no significant effects on AGB,NDVI,and SAVI.Experimental warming significantly(P<0.05)reduced the four-year average vegetation precipitation use efficiency at an elevation of 4313 m,specifically in relatively dry years(P<0.05),rather than relatively wet years.Experimental warming did not significantly affect vegetation precipitation use efficiency at elevations of 4513 and 4693 m.Overall,experimental warming increased the difference in vegetation precipitation use efficiency among the three elevations.Therefore,in alpine grasslands in northern Tibet,the temperature sensitivity of vegetation precipitation use efficiency can vary with elevation and measurement year.Moreover,climate warming can reconstruct the elevational distribution of vegetation precipitation use efficiency in the these grasslands.That is,climate warming can be expected to enhance the elevational heterogeneity of vegetation precipitation use efficiency in the alpine grasslands of northern Tibet.

关 键 词：空间异质性 空间分布格局 资源利用效率 气候变化 高寒生态系统 海拔梯度 

分 类 号：S812[农业科学—草业科学]