湖北省地区植被覆盖变化及其对气候因子的响应

归一化植被指数(NDVI)作为一个重要的遥感参数,能够准确地反映植被覆盖程度和植被生长状况、生物物理化学性质及生态系统参数的变化,其时序数据也已成为基于生物气候特征开展大区域植被和土地覆盖分类的基本手段。基于2001—2012年MODIS-NDVI数据,利用趋势分析法以及线性相关分析等方法对湖北省植被年际变化趋势、月变化趋势进行详细分析;并且研究该区植被覆盖时空变化及其与气温和降水的关系。结果表明近12年来,研究区大部分区域植被覆盖度良好,其中鄂西北及鄂南地区NDVI值较高为0.82,鄂中东部城市NDVI值较低为0.13;2001—2012年间年均NDVI整体呈增加趋势,增速1%/10a;植被覆盖度基本不变区域占研究区总面积的92.8%,大致符合我国中部地区植被覆盖变化趋势;分析NDVI与气候因子的相关关系可知,降水量对湖北植被NDVI年变化起有重要影响;逐月NDVI与月平均气温及月降水量的回归分析表明,降水和气温对生长季不同月份的植被NDVI影响明显不同,同时呈现一定的滞后性。

Analyzing dynamic vegetation change and response to climatic factors in Hubei Province,China

Normalized difference vegetation index (NDVI) is an important remote sensing parameter, it can accurately reflect the degree of vegetation and vegetation growth status, biological, physical, and chemical properties; and the changes in ecological system parameters. Based on its sequence data, it is also used as a bioclimatic character in large vegetation areas and for basic land cover classification. Vegetation cover changes in Hubei in 2001-2012 were analyzed using moderate resolution imaging spectrometer (MODIS) NDVI data. The maximum value composites, trend analysis, and linear regression analysis were used to analyze the annual and monthly NDVI changes of different vegetation types and to characterize the temporal and spatial vegetation cover changes and their relationship with temperature and precipitation. The results showed that vegetation cover was good in most regions of Hubei Province:the NDVI value was the highest (0.82) for the northwest regions and was the lowest (0.13) for the central urban regions. In general, the yearly mean NDVI increased from 2001 to 2012 at a rate of 1%/10 a. A constant area accounts for 92.8% of the total vegetation coverage, which is consistent with the trend of China''s central region vegetation change. Precipitation had a crucial effect on the inter-annual variation of NDVI. The relationships of NDVI across different months during the growing season to temperature and precipitation over 12 recent years indicated that there was an obvious difference in the effects of temperature and precipitation on NDVI among different months in the growth season, and response of NDVI to the climate factors was lagged.