Dynamic characteristics of land degradation development in agricultural oasis of desert-oasis ecotone

To explore the evaluation of land degradation in agricultural region of desert-oasis ecotone, the spatial heterogeneity of topsoil(0～20 cm) and the relationship of such heterogeneity and land use type were studied using a combination of semivariogram and GIS methods. Results show that the development of oasis can be divided into four stages, i.e., excessive land reclamation, moderate land use, land abandonment, land integrated management; human activities are the key factor that results in the increasing of landscape diversity and the fractionizing of the landscape in the last 23 years; from 1983 to 2005, the extent of land degradation was heavier in the area near desert resign than that in oasis; the area of land degradation in gray desert soil was larger than that in solonchak soil and aquert soil, and land degradation was weaker in the regions of bad quality than that in the regions of good quality.