Abrupt vegetation shifts caused by gradual climate changes in central Asia during the Holocene

作     者：ZHAO Yan LIU YaoLiang GUO ZhengTang FANG KeYan LI Quan CAO XianYong 

作者机构：Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences Beijing 100101 China University of Chinese Academy of Sciences Beijing 100049 China Key Laboratory of Cenozoic Geology and Environment Institute of Geology and Geophysics Chinese Academy of Sciences Beijing 100029 China Chinese Academy of Sciences Center for Excellence in Tibetan Plateau Earth Sciences Beijing 100101 China College of Geographical Sciences Fujian Normal University Fuzhou 350007 China Alfred Wegener Institute Helmholtz Center for Polar and Marine Research 14473 Potsdam Germany 

出 版 物：《Science China Earth Sciences》 (中国科学（地球科学英文版）)

年 卷 期：2017年第60卷第7期

页      面：1317-1327页

核心收录：

学科分类：070903[理学-古生物学与地层学(含：古人类学)] 0709[理学-地质学] 07[理学] 

基　　金：supported by the National Natural Science Foundation of China (Grant Nos. 41330105, 41690113 and 41430531) the National Key Research and Development Program of China (Grant No. 2016YFA0600501) the Chinese Academy of Sciences Strategic Priority Research Program (Grant No. XDB03030000) 

主　　题：Fossil pollen Vegetation response Threshold effects Holocene climate Central Asia 

摘      要：Understanding the response of ecosystems to past climate is critical for evaluating the impacts of future climate changes.A large-scale abrupt shift of vegetation in response to the Holocene gradual climate changes has been well documented for the Sahara-Sahel ecosystem. Whether such a non-linear response is of universal significance remains to be further addressed. Here,we examine the vegetation-climate relationships in central Asia based on a compilation of 38 high-quality pollen records. The results show that the Holocene vegetation experienced two major abrupt shifts, one in the early Holocene(Shift I, establishing shift) and another in the late Holocene(Shift II, collapsing shift), while the mid-Holocene vegetation remained rather stable. The timings of these shifts in different regions are asynchronous, which are not readily linkable with any known abrupt climate shifts,but are highly correlated with the local rainfalls. These new findings suggest that the observed vegetation shifts are attributable to the threshold effects of the orbital-induced gradual climate changes. During the early Holocene, the orbital-induced precipitation increase would have first reached the threshold for vegetation establishment for moister areas, but significantly later for drier areas. In contrast, the orbital-induced precipitation decrease during the late Holocene would have first reached the threshold, and led to the vegetation collapse for drier areas, but delayed for moister areas. The well-known 4.2 kyr BP drought event and human intervention would have also helped the vegetation collapses at some sites. These interpretations are strongly supported by our surface pollen-climate analyses and ecosystem simulations. These results also imply that future climate changes may cause abrupt changes in the dry ecosystem once the threshold is reached.