Evolutionary Relation Between Ecological Vulnerability and Soil Erosion in the Typical Reddish Soil Region of Southern China

This study quantitatively determined the amount of soil erosion of the county in 1999 and 2010 respectively, using the Revised Universal Soil Loss Equation (RUSLE). Slope, K factor (soil erodibility), R factor (rainfall erosivity), topography, vegetation coverage and population density were selected as ecological factors for the synergetic assessment between soil erosion and ecological vulnerability based on soil erosion intensity index (E_i) during the past 11 years. The results showed that there was strong correlation in each geographical distribution of grades between soil erosion and ecological vulnerability. There were serious soil erosion and high degree of ecological vulnerability in central and southeastern Changting County, and the proportion of the distribution area decreased gradually from weak grade to severe grade in the same period. From 1999 to 2010, the reduced proportion of each soil erosion grade and each ecological vulnerability grades was from 87.71% to 99.80%, from 43.96% to 73.83%, respectively. The findings indicated the degree of soil erosion and ecological vulnerability was reduced, and the restoration of ecological environment was more difficult than control of soil erosion over the past 11 years. With the difference of degree of ecological vulnerability transform, the regular interval of Ei changing was presented as -95, +44, -147, -104 ∪ +45, +126, -233, -149, respectively, which showed highly synergistic effect with the evolution of ecological vulnerability.