玛曲县草地退牧还草工程效果评价

利用残差趋势法对玛曲县草地退牧还草工程(禁牧、休牧)效果进行了评价,即利用2000～2006年250m的MODIS16天合成NDVI产品数据及同期气象资料,建立工程区内退牧前2000～2004年两种时间尺度(年、月),3种空间尺度(县、乡镇、围栏)的NDVI值同气象要素的回归模型,并利用模型预测无该工程影响下的模拟NDVI值,分析退牧前后模拟NDVI值与实际NDVI值的残差及变化趋势,从而判断退牧还草工程对草地恢复状况的影响,及分析不同工程措施对草地恢复的作用.结果表明,退牧还草工程有利于玛曲县草地牧草生长和草地恢复,但草地恢复效果存在时空差异,退牧还草工程有助于牧草整个生育期的生长,尤其是牧草生长初期和末期效果最为显著.禁牧措施较休牧措施对于草地恢复效果更显著.整个工程区内草地总体处于恢复中,但恢复状况各有差异,一些区域草地恢复状况不理想,说明这些区域还存在较为严重的放牧或不合理放牧行为,退牧还草工程执行力度差.就各乡草地恢复状况而言,曼日玛乡草地总体恢复趋势最好,欧拉乡草地总体恢复趋势相对较差.各乡下辖各围栏区草地恢复效果显著,但个别围栏区草地仍处于恶化趋势,其中恢复效果最好的是16# 围栏区,恶化最为严重的是5#围栏区草地.

The effect evaluation of the program of restoring grazing to grasslands in Maqu County

The effect of restoring grazing to grasslands areas in Maqu County was evaluated in this paper. The 16 days 250m MODIS, annual NDVI and month NDVI data and synchronous meteorological data were used to build some regression models. Using these models we can forecast and evaluate the effect if without the project. Moreover we can use the models to analyze the residual difference change trend of actual NDVI and simulative NDVI from 2000 to 2006, and then to deduce the different project types effect on the grasslands restoring. The result showed that restoring grazing to grasslands was benefit for grassland growing and restoring, especially in the earlier and latter growing seasons. Forbidden grazing measure was the most effective. For the grassland restoring condition, all the grassland areas were in the recovering process, but the effects were various in different areas, and the best condition in Manrima village, the worst in Oula village. As a whole, the project was executed well in most enclosures and the restoring conditions were well, among these enclosures, the 16th enclosure was the best condition. However, some enclosures conditions were bad, such as the 5st enclosure, which can be concluded that there were some absurd grazing behaviors and the project was not well executed in those areas.