桂西北喀斯特区域植被变化趋势及其对气候和地形的响应

基于1999—2010年的SPOT NDVI数据,分析了河池市植被变化趋势及空间差异,并结合气象和地形数据分析了植被与气候、地形的关系。结果表明:(1)桂西北喀斯特地区植被变化总体上呈恢复趋势,年均气候因子对植被变化的作用不明显;(2)200—500m的海拔范围内植被恢复显著,但400—500m的海拔范围内有小面积植被退化现象,随着海拔增加,植被变化趋于稳定;(3)6—15°的坡度范围内植被恢复最显著,而2—6°及大于25°坡度范围存在植被退化的现象;(4)不同坡向上的植被恢复差异不明显,但随着坡向由阴坡转阳坡,植被总体恢复呈减小趋势。喀斯特地区人类生态建设取得一定成效,但由于人类活动的负面影响,在海拔400—500m、坡度大于25°的阳坡区域仍存在植被减少的现象。

Trends in vegetation and their responses to climate and topography in northwest Guangxi

The annual dynamics and spatial variability of vegetation in northwest Guangxi were studied based on the SPOT NDVI datasets during 1999-2010. The response of vegetation to climate and topography was analyzed. The results showed that: (1) Vegetation had a large proportion of increasing trends in northwest Guangxi from 1999 to 2010. Partial correlation analysis between NDVI and climate parameters showed that climate had little effect on vegetation.(2) Elevation affected vegetation trend. It increased between 200 and 500 m, however, there were a small areas between 400 m and 500 m where vegetation decreased. Vegetation tended to be stable as the elevation increasing. (3) Vegetation recuperated on slopes between 6°and 15°, but decreased on slopes between 2°and 6° and above 25°. (4) The differences of vegetation restoration on aspects were not obvious. However, vegetation recovery trended to be decreasing as the aspect turning from shady to sunny slopes. Our study indicated that the implementation of environmental conservation policies and ecological construction had resulted in the improvement of vegetation in karst regions. However, there were some regions with vegetation degradation caused by human disturbance. In the further implementation of ecological restoration, the government should pay more attention to the sunny regions where the elevation between 400m and 500m and the steep slope that larger than 25°.