Abstract:

Because of the solubility of carbonate rock,the instability of karst soil and the vulnerability of karst vegetations,the risk of water and soil loss is bigger in carbonate rock areas than in noncarbonate rock areas.The effects of lithology to sensitivity of water and soil loss are stronger in carbonate rock areas than noncarbonate rock areas.This paper is the basic study of ecological function division.To these facts and the ecological characters of karst area,considering the difference of lithology as the dominant factor,the accountable factors were identified as the assessment indices respectively in carbonate rock areas and noncarbonate rock areas,and the possibly sensitivity degree and distribution law of water and soil loss were analyzed based GIS technology.The results showed that the sensitivity assessment of water and soil loss sensitivity in northwest of Guangxi could reflect the fact on the whole.The areas percentage of water and soil loss sensitivity was above 99%,and there is a visible higher sensitivity degree in karst areas than in nonkarst areas.To the whole region,the integrated sensitivity degree of water and soil loss was higher,and the area percentage of intense and extreme reached 31% and 237%,respectively.These area mainly distributed in Duan and Dahua in the south of Hechi region and karst mountain area in the middle and north of Hechi region.To different sensitivity degree,water and soil loss types and distribution characteristics,this paper put forward relevant measures of developmentmanagement,in order to provide references of ecosystem restoration and sustaining development in the karst regions.

Key words: karst/water and soil loss sensitivity/spatial distribution/northwest of Guangxi