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Facing the worsening degradation of grasslands, state and local governments in China have implemented a series of ecological protection projects. Ningxia Hui Autonomous Region was the first province in China to implement a region-wide grazing ban, the effect of which has become contentious at all levels of government and a topic of public concern. The change of grassland desertification is the most direct indicator of the grazing ban’s effect. This paper chooses Yanchi County in Ningxia as the study area to analyze the grassland desertification situation. Based on a series of Landsat TM/ETM+ images, field observations and expert review, a Ningxia grassland desertification classification and grading system was constructed. Then, spectral mixture analysis (SMA) and a decision-tree method were used to interpret images of the study area from 4 years: 1993, 2000, 2006, and 2011. The following results were obtained: the area of desertified grassland decreased gradually from 4142\;\km^2 in 1993 to 3695\;\km^2 in 2011, a decrease of 10.80%. The severity of desertification also declined as the area of severely desertified grassland gradually decreased to 324\;\km^2 in 2011 from 1093\;\km^2 in 1993, a decrease of 70.34%. The annual reduction rate of the desertified grassland area reached its peak during the period 2000–2006. In particular, the areas of severely desertified grassland declined by 8.86% annually. In a situation of declining rainfall, human factors (such as ecological protection policy) have become a major cause of ongoing grassland desertification reversal and restoration of grassland vegetation. [ABSTRACT FROM PUBLISHER]

Abstract: State and local governments in China have implemented a series of grassland protection policies to address the problem of grassland degradation. In 2003, Ningxia was the first province to implement a province-wide grazing ban. The effect of this ban is contentious at all levels of government and has become a topic of public concern. Grassland desertification is the most direct indicator of the effect of the grazing ban. We selected 14 counties and cities in north-central Ningxia as the study area. A desertification classification and grading system for Ningxia's grassland was then designed based on fieldwork and expert review. Using the Spectral Mixture Analysis (SMA) and decision-tree methods, we interpreted Landsat TM/ETM+ images of the study area during four years: 1993, 2000, 2006 and 2011. The following results were obtained: from 1993 to 2011, the area of desertified grassland in north-central Ningxia decreased gradually from 8702km2 in 1993 to 7485km2 in 2011, a decrease of 13.98%; the degree of desertification gradually decreased from 3573km2 of severely desertified grassland in 1993 to 1450km2 in 2011, a decrease of 59.41%; desertified grassland vegetation was restored rapidly during 2000–2006 and 2006–2011, reducing the total area of desertified grassland annually by 1.87 and 0.61%, respectively; finally, the area of severely desertified grassland decreased annually by 5.78 and 6.28% during 2000–2006 and 2006–2011, respectively. These results show that the region-wide grazing ban, together with other ecological engineering measures, has helped reverse desertification and promote the restoration of grassland vegetation. [Copyright &y& Elsevier]