摘要
Global vegetation photosynthesis and productivity have increased substantially since the 1980s,but this trend is heterogeneous in both time and space.Here,we categorize the secular trend in global vegetation greenness into sustained greening,sustained browning and greening-to-browning.We found that by 2016,increased global vegetation greenness had begun to level off,with the area of browning increasing in the last decade,reaching 39.0 million km^(2)(35.9%of the world’s vegetated area).This area is larger than the area with sustained increasing growth(27.8 million km^(2),26.4%);thus,12.0%±3.1%(0.019±0.004 NDVI a^(-1))of the previous earlier increase has been offset since 2010(2010–2016,P<0.05).Global gross primary production also leveled off,following the trend in vegetation greenness in time and space.This leveling off was caused by increasing soil water limitations due to the spatial expansion of drought,whose impact dominated over the impacts of temperature and solar radiation.This response of global gross primary production to soil water limitation was not identified by land submodels within Earth system models.Our results provide empirical evidence that global vegetation greenness and primary production are offset by water stress and suggest that as global warming continues,land submodels may overestimate the world’s capacity to take up carbon with global vegetation greening.
大尺度的研究表明全球植被光合能力和生产力自20世纪80年代以来持续增加,但是很少有研究关注到其时空异质性.本研究将全球植被绿度变化趋势分为持续变绿、由变绿转为变棕、持续变棕以及不显著变化等不同类型,发现全球植被绿度变棕区域持续增加.到2010年以后逐渐超过持续变绿的区域(27.8×10^(6)km^(2),26.4%),达到了39.0×10^(6)km^(2)(全球植被面积的35.9%).这一现象抵消了2010年前12.0%±3.1%(0.019±0.004 NDVI a^(-1))植被绿度增加(2010~2016,P<0.05).全球陆地生态系统初级生产力也表现为类似的变化特征.这种变化主要是由于土壤水对于植被胁迫的负向作用,在部分地区超过了温度和辐射对于植被光合的积极作用.目前地球系统模型中的相关模块并不能反映这一正在增加的植被土壤水分胁迫.研究提示随着全球升温作用进一步加强,目前的地球系统模型土地模块可能会高估全球陆地生态系统碳固持能力.
作者
Xiaoming Feng
Bojie Fu
Yuan Zhang
Naiqing Pan
Zhenzhong Zeng
Hanqin Tian
Yihe Lyu
Yongzhe Chen
Philippe Ciais
Yingping Wang
Lu Zhang
Lei Cheng
Fernando T.Maestre
Marcos Fernández-Martínez
Jordi Sardans
Josep Peñuelas
冯晓明;傅伯杰;张园;潘乃青;曾振中;田汉勤;吕一河;陈永喆;Philippe Ciais;王应平;张橹;程磊;Fernando T.Maestre;Marcos Fernández-Martínez;Jordi Sardans;Josep Peñuelas(State Key Laboratory of Urban and Regional Ecology,Research Center for Eco-Environmental Sciences,Chinese Academy of Sciences,Beijing 100085,China;University of Chinese Academy of Sciences,Beijing 100049,China;State Key Laboratory of Earth Surface Processes and Resource Ecology,Faculty of Geographical Science,Beijing Normal University,Beijing 100875,China;International Center for Climate and Global Change Research,School of Forestry and Wildlife Sciences,Auburn University,Auburn,AL 36832,USA;School of Environmental Science and Engineering,Southern University of Science and Technology,Shenzhen 518055,China;Laboratoire des Sciences du Climat et de l’Environnement,CEA CNRS UVSQ,Gif-sur-Yvette 91191,France;Oceans and Atmosphere,Commonwealth Scientific and Industrial Research Organisation,Aspendale,Victoria 3195,Australia;South China Botanic Garden,Chinese Academy of Sciences,Guangzhou 510650,China;Land and Water,Commonwealth Scientific and Industrial Research Organisation,Black Mountain,Canberra,ACT 2601,Australia;School of Water Resources and Hydropower Engineering,Wuhan University,Wuhan 430072,China;Departamento de Ecología and Instituto Multidisciplinar para el Estudio del Medio“Ramon Margalef”,Universidad de Alicante,Alicante 03690,Spain;Global Ecology Unit CREAF-CEAB-UAB,Spanish National Research Council,Cerdanyola del Vallès,Catalonia 08193,Spain)
基金
the National Key Research and Development Program of China(2017YFA0604700)
the National Natural Science Foundation of China(41722104)
the Key Research Project of Chinese Academy of Sciences(QYZDY-SSWDQC025 and 2019DC0027)
supported by the European Research Council Synergy(ERC-2013-Sy G-610028 IMBALANCE-P)
the Spanish Government(CGL2016-79835)
the Catalan Government(SGR 2017-1005)。
