Abstract: To reveal altitudinal spatial variability of ecological degeneration in Bijie Prefecture,Guizhou Province,vertical gradient of ecological degeneration indexes were analyzed using geostatistics.The study site is in the centre of Yunnan,Guizhou,Guangxi Karst area where the altitudinal variation ranges widely.The optimal semivariogram theoretical model of bedrock exposure rate was linear with a sill model;the vegetation cover and soil gravel rates were a spherical model.The spatial relativity of vegetation cover was strong with vertical gradient and it was mainly affected by natural control factors with altitudinal variation.The rate of nugget to sill was 22.32%.The spatial relativity of bedrock exposure and soil gravel rate were moderate with vertical gradient and they were mainly affected by random factors.The rate of nugget to sill were 34.38% and 25.97%.The ranges of soil gravel rate and vegetation cover were 968.10 and 859.48 m.These data showed that soil gravel rate and vegetation cover were affected by wide altitudinal ranges.The range of bedrock exposure was 52.28 m indicating that it is affected by narrow ranges.Moran’s I for bedrock exposure and vegetation showed similar trends along altitudinal gradient;however,that for soil gravel rate was quite different.

Key words: Karst, ecological degeneration, altitudinal, geostatistics, spatial variability