Changes of Vegetation Coverage During Recent 18 Years in Lianjiang River Watershed

With TM images as a data source,this paper calculates and analyses the characteristics of change and spatial distribution about the vegetation in Lianjiang watershed in 1988–2006 by using the dimidiate pixel model based on NDVI.Overlaying the vegetation coverage map and the sub-karst geological map,the impact on vegetation coverage exerted by geological structure is analyze.The results can be described in the following three aspects.1) Because of the effect of climate and human activities,the vegetation coverage in Lianjiang River watershed got a rise in 1988–2006.The area of higher and high vegetation coverage districts increased,while that of low,lower and middle vegetation coverage districts decreased.2) The quality of vegetation in non-karst district was better than that in karst district due to the influence of geological formation.3) The change of vegetation coverage's spatial distribution was significant in Lianjiang River watershed during the recent 18 years.