The effect of rocky desertification on the soil’s organic carbon storage in karst peak cluster: A case study in Yanbei town, Yingde City, Guangdong Province

In order to analyze the effect of rocky desertification on the storage of soil organic carbon, sample plots with different degrees of rock desertification in a typical karst peakcluster in the Tangbian village, Yanbei town, Yingde City, the north of Guangdong Province are selected in this paper, and a new index of unit area soil organic carbon is adopted in the analysis on the effect of rocky desertification process to the organic carbon storage. The results show that: (1) The thickness of soil and standing biomass decreased significantly and the rock coverage increased significantly in intense rock desertification，but the difference are not significant between potential, slight and medium rock desertification in soil thickness, standing biomass and rock coverage. (2) Obviously, organic carbon content per unit of soil weigh is highest in intense rock desertification plots. It is higher in medium than in slight rock desertification plots, and it is higher in slight than in potential desertification plots, but the difference is not significant between medium, slight and potential rock desertification. (3) The soil organic carbon content in 10-20 cm soil depth is lower than that in 0-10 cm. Water and soil losing leads rocky coverage increase and only a little soil remain in the fissure of rock, those micronegative relief can capture organic matter, that may be the major cause for the increase of soil organic carbon in intense and medium rock desertification. (4) The soil organic carbon content per unit area of in medium, slight and potential rock desertification is 49.23, 47.9 and 29.4 times of that in intense rock desertification. (5)The rock coverage is the main factor that impacting the karst ecological system. There is significant negative correlation between the rock coverage and the ground biomass, between the rock coverage and unit area of soil organic carbon, and between the rock coverage and thickness of soil. Highly adaptive plants in karst area can weaken the effects on soil organic carbon by rock desertification.