Quantitative evaluation of the effect of prohibiting grazing policy on grassland desertification reversal in northern China

In northern China, the recent eco-environment protective policies played a very important role in the ecological environment protection and rehabilitation. To better understand the quantitative effect of the prohibiting grazing policy on grassland desertification reversal process, in this paper, Yanchi County was selected as a case study to conduct a quantitative research on the effect of prohibiting grazing policy. System dynamics research method was used in this study, also both natural factors and human factors which importantly related to desertification had been considered in the index system of the system dynamics method. According to the different grazing prohibition degree from 0 to 100 %, model was set up to simulate the grassland desertification degree. The results showed that grassland desertification degree decreased with the increase of the grazing prohibition degree. When the grazing prohibition degree was 30 %, grassland desertification began to reverse, and when the grazing prohibition degree was 40 %, the trend of grassland desertification reversal was steady, and the speed of desertification reversal was the same when the grazing prohibition degree changes from 40 to 100 %. Therefore, the full prohibiting grazing policy in Yanchi County currently is not necessary at all. These results could be very useful for the applying of prohibiting grazing policy in Yanchi County and other regions with the similar ecoenvironment protective policies.