干旱区生态环境知识资源中心

Large-scale cropland changes have significant implications for global and national food supply as well as degradation in land resources. We examined cropland dynamics at the national scale in Mongolia over the last three decades using Google Earth Engine cloud computing and 11,360 Landsat satellite images. Our overarching goal was to develop the first comprehensive, high-resolution maps of Mongolia’s cropland extent for two nominal years: 1990 at the peak of the socialist era production and 2014 after major socio-political and economic regime changes. By comparing the two cropland maps, we estimate cropland changes and identify areas of post-socialist cropland abandonment. Our cropland classifications produce high overall accuracies (overall weighted, statistical accuracies of 98% and 97%, respectively), and the cropland area estimates compare well with county-level crop area statistics (R-2=0.91, p value <.001). We estimate 38% cropland decline in Mongolia throughout the major crop regions but 18% increase in the central region due to increased concentration of crop production. The observed large-scale cropland abandonment would be expected to result in substantial land conversion to rangelands as well as land degradation in the abandoned fields, including soil erosion, increased contribution to desertification, and reduced species diversity. Future studies can monitor the long-term trajectory in the abandoned crop fields and recommend targeted restoration strategies.