2000—2015年青藏高原植被NPP时空变化格局及其对气候变化的响应

Spatial and temporal patterns of NPP and its response to climate change in the Qinghai-Tibet Plateau from 2000 to 2015

全球变化背景下,青藏高原作为我国乃至全球气候变化的"天然实验室",植被生态系统发生了深刻变化。引入重心模型等方法分析和探讨2000—2015年青藏高原植被NPP时空变化格局及其驱动机理,并定量区分NPP变化过程中气候变化和人类活动的相对作用。研究发现:(1)2000—2015年,青藏高原植被NPP年均值总体上呈现从东南向西北递减的趋势。在年际变化方面,近16年植被NPP呈现波动上升趋势,其中在2005年出现上升陡坡,并在2005—2015年表现为高位波动的态势。(2)青藏高原植被NPP增加区(变化率>10%)主要集中于三江源地区、横断山区北部、雅鲁藏布江中下游以及那曲地区的中东部,而植被NPP减小区(变化率<-10%)则主要分布于雅鲁藏布江上游和阿里高原。(3)近16年青藏高原植被NPP重心总体向西南方向移动,表明西南部植被NPP在增量和增速上大于东北部。(4)青藏高原植被NPP与气候因子相关性的地区差异显著,其中植被NPP与降水显著相关的区域主要位于青藏高原中部、青藏高原东南部及雅鲁藏布江流域中下游,而植被NPP与气温显著相关的区域主要位于藏南地区、横断山区北部、青藏高原中部和北部。(5)气候变化和人类活动在青藏高原植被NPP变化过程中的相对作用存在显著的时空差异性,在空间上呈现"四线—五区"的格局。研究成果能够为揭示青藏高原区域生态系统对全球变化的响应机制提供理论和方法支撑。

The Qinghai-Tibet(QT)Plateau is considered as the"natural laboratory"of climate change in China and even in the world.Under the background of global change,the vegetation ecosystem of the QT has undergone profound changes.In this study,the spatian and temporal patterns and its driving mechanisms of NPP in the QT Plateau from 2000 to 2015 were analyzed and discussed by using gravity center and correlation coefficient models.Then,the relative effects of climate change and human activity on the process of NPP changes was quantitatively distinguished.The results show that:(1)From 2000 to 2015,the annual mean NPP in the QT Plateau showed a decreasing trend from southeast to northwest.In terms of interannual changes,the annual mean NPP showed a fluctuating upward trend in the study period,with a sharp rise in 2005 and a high fluctuation during 2005-2015.(2)The increased area of NPP in the QT Plateau(change rate>10%)was mainly concentrated in the Three-River Source Region,the northern Hengduan Mountains,the middle and lower reaches of the Yarlung Zangbo River Basin and the central and eastern parts of Naqu county,while the decreased area of NPP(change rate<-10%)was mainly distributed in the upper reaches of the Yarlung Zangbo River Basin and the Ali Plateau.(3)During the 16 years,the gravity center of NPP in the QT Plateau moved eastward,indicating that the increment and growth rate of NPP in the eastern part is greater than that in the western part.(4)The correlation between vegetation NPP and climate factors in the study area is significant.The regions with significant correlation between NPP and precipitation are mainly located in the central and the southeastern parts of the QT Plateau and the middle and lower reaches of the Yarlung Zangbo River Basin.The regions with significant correlation between vegetation NPP and temperature are mainly located in Southern Tibet,Northern Hengduan Mountains,Central and Northern QT Plateau.(5)The relative effects of climate change and human activity on the process of NPP change in the plateau have significant spatial and temporal differences with a distribution pattern of"Four Lines and Five Regions".The research results can provide theoretical and methodological supports for revealing the response mechanism of regional ecosystems to global change in the QT Plateau.