Spatial Distribution and Simulation of Cropland Abandonment in Wushan County, Chongqing, China

Abstract

Cropland abandonment (CRA) is an extreme case of cropland marginalization. With the continuous development of global industrialization and urbanization, the phenomenon of CRA gradually spreads from developed countries such as eastern and western European countries and the United States to developing countries such as China, especially in regions with poor geographical conditions such as mountainous areas. However, research on CRA in developing countries is sparse, and adequate identification methods and spatial distribution information are lacking in China, impeding the comprehensive understanding of the status quo of CRA as well as the formulation of related policies and measures. Therefore, taking Wushan County in Chongqing as an example, we developed a CRA extraction method to identify cropland. Landsat 8 OLI_TIRS remote sensing images were adopted in the extraction. Subsequently, Google Earth images were used to verify the extraction results, and the extraction accuracy of abandoned cropland plaques reached 89.33%. The CRA rate in Wushan between 2011 and 2016 was 28.71%, and abandoned cropland was highly scattered across the region. In areas above 800 m and with slopes of more than 15°, large areas were abandoned. However, an increasing irrigation radius resulted in higher labor costs and, ultimately, larger abandoned areas. Using the Conversion of Land Use and its Effects-Small (CLUE-S) model, the CRA status under different scenarios was simulated, and under the scenario of economic development, the CRA rate in the next 20 years was as low as 28.84%, while under the scenario of natural growth, the rate reached 33.54%. When the model used the scenario of ecological protection, the cropland area in Wushan County decreased significantly, and the CRA rate reached 42.11%.