Abstract:

Choosing Yuanmou dryhot valley as a study area,MSS,TM,ETM and CBERS2 CCD images as data source,we extracted apparent reflectance,NDVI,three topographic factors from DEM,and applied GIS overlay method to analyze vegetation change process.Results showed that over the past 30 years,vegetation change of Yuanmou dryhot valley went through a slow recovery after severe degradation.During this period,recovery results of such elevation zones as 1 600~2 000 m,≥2 000 m,slope zone as ≤5°,and aspect zone as -1 were obvious and continuous stability.While in the elevation zone of ≤1 100 m,slope zones of 5~10° and 10~25°,and aspect zones of 2925~3375°,675~1125°,3375~225° and 225~675°,a strong recovery process was accompanied by a strong degradation process.Those elevation zones of 1 100~1 350 m and 1 350~1 600 m,slope zones of 25~35° and ≥35°,and aspect zones of 1575~2025°,2025~2475°,2475~2925°,and 1125~1575° showed degradation trends after 1999.Response rate of vegetation destroy or recovery in the elevation zone of ≥2 000m,slope zone of ≥35°,and aspect zones of 3375~225°and 225~675° were the highest. On the whole,differences of vegetation restoration spatial pattern and sustainability in different topographic conditions are significant,and adjustments and optimizations of restoration countermeasures should be targeted in time