山西典型生态区植被指数(NDVI)对气候变化的响应

Responses of vegetation index (NDVI) in typical ecological areas of Shanxi Province to climate change

利用1982—2006年8km的NSASA/GIMMS半月合成的月植被指数(NDVI)和同期气候数据,根据山西地形地貌结合土地利用及植被调查资料,将山西划分为9个区域,分析了这9个典型生态区的NDVI年际、年代际以及月季的变化规律,同时分析了NDVI对降水、气温以及干旱指数PDSI等气候要素的响应特征。结果表明:近25年来山西植被指数呈起伏上升趋势,并存在明显的年际变化;NDVI在空间变化上表现为南部好于北部、东部好于西部,不同生态区中林区>农业区>农牧区;林区春季植被指数显著上升,除晋南农业区月变化为双峰型外,其他生态区均表现为单峰型;林区NDVI与气温存在一致相关,PDSI与NDVI的相关好于降水、气温单一因子;植被指数对气候年际变化响应有明显的滞后性,降水的年际变化对植被指数影响最大,尤其是降水的累积效应。

By using the 1982-2006 NASA/GIMMS half-monthly composite NDVI data of 8 km resolution and related climate data, and based on the investigations of terrain, land use, and vegetation, this paper classified Shanxi Province into 9 typical ecological areas, and analyzed the dynamic changes of annual, decadal, and monthly NDVI as well as the responses of the NDVI to precipitation, air temperature, and PSDI in the areas. The results indicated that in recent 25 years, the NDVI in the Province had an increasing trend, and exhibited an obvious annual variation. The NDVI was higher in southern part than in northern part, and in eastern part than in western part. For different ecological areas, forested area had the highest NDVI, followed by agricultural area, and pasturing area. The vegetation index in forested area increased obviously in spring, and that in most ecological areas except southern agricultural area represented single apex type. The NDVI in forested area related well with air temperature, and the correlation of NDVI with PDSI was more closely than with precipitation or air temperature. The responses of vegetation index to climate change had an obvious lag effect, and the annual variation of precipitation, especially the accumulative effect of precipitation, affected vegetation index significantly.