1982–2012年中亚植被变化及其对气候变化的响应

Vegetation change and its response to climate change in Central Asia from 1982 to 2012

归一化植被指数(NDVI)能够反映植被生长状况,被广泛应用于区域乃至全球的植被变化研究中。该文利用1982–2012年GIMMS-NDVI数据,通过基于像元的线性趋势分析、偏相关分析,基于场域的经验正交分解(EOF)、奇异值分解(SVD),综合时间和空间两个维度上的信息,研究了近31年来中亚植被的变化及其变化中的区域差异,分析了植被对气候变化的响应关系。线性趋势分析发现,34%的中亚植被NDVI显著增长(p<0.05),山区植被NDVI的增长速率可达到每年0.004。偏相关分析表明,63%的中亚植被受到降水的显著影响(p<0.05,仅4%为负相关),而32%的植被受到气温的显著影响(p<0.05,仅9%为正相关)。EOF分析发现,中亚植被NDVI的变化表现出较大的空间差异:山区及东北部的植被NDVI变化主要分为3个阶段,即先增长(1982–1994年)、后波动(1994–2002年)、然后继续增长(2002–2012年);而西北部平原区的植被NDVI变化主要表现为两个阶段,即先增长(1982–1994年)而后减少(1994–2012年)。SVD分析表明:1982–2012年间中亚植被受到降水和气温的共同影响,植被NDVI的空间变化特征与降水的空间变化特征较为一致,但西北部和山区的植被NDVI对气温的响应存在差异。

Aims Central Asia is one of the most vulnerable and sensitive areas to the change in climate. To understand the response of Central Asia ecosystems to climate change, it is important to improve our understanding of vegetation change and its response to climatic variations. Our objective is to explore and analyze the normalized difference vegetation index（NDVI） and its response to climate change in Central Asia during the period 1982–2012. Methods The linear regression, the empirical orthogonal function（EOF）, the singular value decomposition（SVD） and the partial correlation analysis were used to analyze the NDVI change and its response to climate factors in Central Asia during the period of 1982–2012. Important findings 34% of vegetation in Central Asia showed a pronounced change in NDVI with a significant trend of increase（p〈0.05） and the rate of increase in NDVI exceeded 0.004 per year for mountainous regions. Both air temperature and precipitation showed significant effects on NDVI. Based on partial correlation analysis, 63% of vegetation was found to be significantly affected by precipitation（p〈0.05） while 32% vegetation was affected by air temperature（p〈0.05）. The NDVI changes showed increasing trend from 1982 to 1994, fluctuations between 1994 and 2002, and increasing trend again from 2002 to 2012 in mountainous and northeastern areas. While the NDVI changes experienced increasing trend from 1982 to 1994 but decreasing trend from 1994 to 2012 in northwestern areas. Based on the analysis of SVD, the spatial patterns of NDVI variations were consistent with the spatial patterns of precipitation variations. However, the temperature responses of vegetation NDVI differed across the northeast and the mountainous regions in Central Asia.