巴里坤草原面积动态及其气象因素分析

利用2003-2012年7月巴里坤250 m分辨率的EOS/MODIS卫星影像数据, 通过预处理、几何校正计算归一化植被指数(NDVI);利用巴里坤1∶250 000的土地类型分类图, 在GIS支持下, 提取巴里坤近10年的草地NDVI信息数据, 并以2003年巴里坤草地NDVI为本底数据, 计算巴里坤草地面积的动态变化, 结合相应年份的气象数据进行分析。结果表明, 巴里坤高覆盖草地面积保持相对稳定;中覆盖草地面积年际间变幅较大;低覆盖草地与荒漠化草地在面积上呈现明显的此升彼降的关系。说明两者之间存在明显的相互“转化”关系:若降水充足, 则荒漠化草地向低覆盖草地转化;若降水不足, 则低覆盖草地退化为荒漠化草地。降水和气温是影响巴里坤草地生长的两个重要气象要素, 尤其是4-6月的降水将直接影响当年草产量。

Dynamic variation of grassland area and meteorological influence analysis in Barkol

Using consecutive 10 years EOS/MODIS data with 250 m resolution from 2003 to 2012 in Barkol, NDVI was calculated with Maximum Value Composite approach after pre-processing, geometry emendation. Based on the GIS, 10 years NDVI information was distilled using the Land type classification map of Barkol with the scale of 1∶250 000 and the dynamic variety of NDVI was achieved during this consecutive 10 years with 2003 as background. The results showed that the area of high vegetation coverage grassland was relatively stable in Barkol and the annual amplitude area of middle vegetation coverage grassland varied obviously. If the area of low vegetation coverage grassland rise and that of the desertification grassland will fall and vice versa which showed that there was conversion relationship between them. If there was enough water, desertification grassland will transform to low vegetation coverage grassland and vice versa. Precipitation and temperature were two key factors for grass growth in Barkol, especially the precipitation from April to June.