Patterns and Dynamics of Plant Diversity and Soil Physical-Chemical Properties of the Karst Rocky Desertification Ecosystem, SW China

Three typical rocky desertification regions of South China Karst were selected as experiment sites. Ninety plots, each with an area of 20 m x 20 m, representative of the five degrees of rocky desertification (nil, potential, slight, moderate and severe) were established, and plant diversity and soil physical-chemical properties were surveyed and analyzed. The vegetation of rocky desertification ecosystems proved to be very simple with an extremely low species richness index. With increased degree of rocky desertification, there are remarkable changes in plant diversity: species number declines; the ratio of dominant species importance value is higher; species composition becomes more disorder. There are significant differences in plant diversity indices among different degrees of rocky desertification. On the large scale, evenness and dominance indices of plant diversity increase and the Shannon-Wiener index decreases along the increased gradient of desertification. There were also significant differences in soil physical-chemical properties among the five degrees of desertification. Both physical and chemical properties do not always degenerate with increased degree of rocky desertification. Instead, properties initially degenerate and then improve. And there was a remarkable correlation between soil physical-chemical properties and plant diversity. All these offer bases to clarify the evolution law and formation mechanism of plant diversity and soil physical-chemical properties in karst rocky desertification ecosystem, and have extremely important value in the rehabilitation of the karst rocky desertification ecosystem.