Abstract: In this paper, site investigation and fixed position observation  were conducted in the sampling plots with four different stages of rock desertification in rocky desertification area of northern Guangdong to study  the  vegetation degradation and its modeling in rocky desertification area. With the development of rocky desertification, the plant community structure in the study area became increasingly simpler, with the dominant plant species evolved from Pistacia chinensis + Boehmeria nivea + Vitex negundo + Pueraria phaseoloides to Pistacia chinensis + Artemisia carvifolia + Dendranthema indicum to Miscanthus floridulus + Arundinella anomala + Eleusine indica to Fissidens zippelianus. The community’s layer was from 4 layers to 3 layers to 2 layers to 1 layer, and the proportion of species reduction was from 0 to 14% to 46% to 86%.  The soil organic matter, total N, available N, available P, and available K contents were all decreased significantly with the development of rocky desertification. Vegetation degradation could be described by the competition models of different species to certain kinds of resources, and thus, a model was established for the vegetation degradation in rocky desertification area of northern Guangdong.

Key words: remote sensing, water deficit index (WDI)., soil moisture, summer maize