Evaluating the vegetation restoration sustainability of ecological projects: A case study of Wuqi County in China

Grain for Green project has achieved substantial results in ecological reconstruction and social benefits in China. Meantime, some doubts also exist, and one of the most concerned themes is its sustainability. Although some studies address this topic, there are deficiencies in the research scale and depth. In this work, except for traditional growth trend analysis of vegetation restoration by using vegetation index from 2000 to 2016 in Wuqi County of China, Moran's I was used to analyze the competition for water and nutrients among the vegetation due to restricted space, and the Hurst exponent was used to analyze the future development trends of the vegetation cover. The results show that although the vegetation coverage rate of the study area has improved steadily since the implementation of the ecological policy, limited further improvement in the study area is possible in the future; and vegetation restoration is generally sustainable in the southeastern part of the study area but not in the northwestern part of the study area from a spatial perspective. In terms of driving factors, natural factors are the decisive factors affecting the sustainability of vegetation restoration; ecological projects and maintenance measures may promote vegetation restoration generally but they should be controlled at a certain level, otherwise, the counterproductive result would be obtained. Therefore, vegetation restoration should be adapted to local conditions rather than uniform standards being adopted for the entire region, and this conclusion should apply equally to ecological restoration efforts in other regions of the world. Also, from a methodological point of view, this study proposes to analyze the sustainability of vegetation restoration based on the spatial and temporal perspectives by using the spatial autocorrelation and Hurst exponent methods, which is a development and supplement to previous studies and has a certain advantage for evaluating the vegetation restoration status. (C) 2020 Elsevier Ltd. All rights reserved.