Evaluation on the ecosystem health of national key ecological function areas for karst rocky desertification prevention and control in Guizhou Province

The national key ecological function areas for karst rocky desertification prevention and control in Yunnan, Guangxi and Guizhou are the important ecological regions where development is restricted at the national level. These areas host special ecological systems dominated by karst environments. Of them, the key area of Guizhou Province is located in the upper reaches of the Yangtze River and the Pearl River, a vital ecological barrier for the Yangtze River basin and the Pearl River basin. It is responsible for water conservation, soil and water conservation and other important ecological services. This functional area includes 9 counties subordinated to 4 cities with a total area of 26,454 km2. According to the different landforms and ecological functions, it is divided into four sub-areas， the Weining-Hezhang plateau watershed, Guanling-Zhenning plateau canyon, lower reach of the Ceheng-Wangmo Nan-Beipan River, and the Luodian-Pingtang plateau valley. This paper focuses on this functional area of Guizhou. Based on remote sensing images, geographic information data, precipitation data and soil data of year 2010 and 2015, by integrating 3S ecological and ecological assessing model, a quantitative and positioning analysis is performed to water conservation, soil erosion and rocky desertification degrees. The results show that， (1) Four sub-areas are at a medium or ‘high’ level of water conservation function, and water conservation index of 2015 was enhanced with respect to 2010；(2)The soil erosion modulus of Weining-Hezhang, Guanling-Zhenning and Ceheng-Wangmo areas are high, while their soil and water conservation functions are of low ranks. The soil erosion modulus of the Luodian-Pingtang area is the lowest, and its soil and water conservation function is of medium rank； (3) In the Weining-Hezhang area, the proportion of moderate and high rocky desertification reached 16.36% in 2010, and dropped to 8.74% in 2015. The ecosystem health degree changed from low to medium. The proportion of moderate and high rocky desertification in the Guanlin-Zhenning area was 8.64% in 2010 and 4.49% in 2015, respectively. The ecosystem health degree changed from medium to high. The health degrees of both Ceheng-Wangmo and Luodian-Pingtang are high, which were improved in 2015 compared to 2010. In the four sub-areas, the proportions of rocky desertification deteriorated areas are less than 1.00%, and the proportions of rocky desertification improved areas are 27.00%, 14.10%, 10.24% and 5.13%, respectively, indicating that rocky desertification has been effectively curbed. In the future, we should continue to adapt to local conditions to restore the vegetation and ecological system, and expand the achievements in the prevention and control of rocky desertification.