30 a来共和盆地贵南县草地时空变化分析

 草地资源分布和动态变化是荒漠化监测的重要内容。利用1976年、1996年、2001年、2006年四期遥感影像，在RS与GIS支持下解译提取了贵南县草地信息，通过动态度模型和空间变化分析了青海省贵南县草地资源变化。结果表明：30 a来青海省贵南县草地面积减少了12.62%，其中高盖度草地面积减少了28.87%；主要转化为耕地、未利用地和林地；1996—2006年，草地面积缩减趋缓。1976—1996年间有16.6%的高盖度草地退化为中低盖度草地；1996—2006年高、中、低盖度草地面积转换变化不大。通过草地斑块的重心分析显示草地空间变化向多个方向偏移。

Spatio-temporal Change of Grassland Based on GIS and RS in 30 Years in Guinan County, Gonghe Basin

Grassland distribution and change dynamics are main objects of desertification monitoring. By using four-period remote sensing images(1976, 1996, 2001, 2006) and under the support of RS and GIS techniques, the spatial information of grassland during the past 30 years in Guinan County, Qinghai Province is interpreted and extracted, and the area, quality and spatial change pattern of grassland are analyzed in this paper. The results shows that: ①The grassland area was decreased by 12.62% in the past 30 years, and grassland degradation is serious, especially for high coverage grassland with a net decreasing rate of 28.87%; During 1976—1996, grassland is mainly converted into cropland, wilderness and forest land, and the converted area of the high coverage grassland occupied 85.9% of total converted area. During 1996—2006, the trend of grassland degradation is slow.②The grassland had greatly degraded from 1976 to 1996, the main reason was that 16.6% of high coverage grassland were converted into middle and low coverage grassland. In the period of 1996—2006, the change of the grassland dynamic degree was small and the area of different coverage grade grassland nearly kept stable. ③The change of gravity center of grasslands is irregular and multi-directional because both natural factor and human actions take effect on grassland in the region.