Assessment of Cropland Abandonment and Vegetation Recovery on the Chinese Loess Plateau

Abstract

Cropland abandonment alters agricultural land use and may enable improvements in vegetation cover. On the Chinese Loess Plateau, the extent and spatial variation of these changes remain critical questions for land management. This study used annual land-cover trajectories to identify persistent cropland withdrawal from 2000 to 2020 and Landsat-derived fractional vegetation cover (FVC) to assess vegetation change. The total first-abandonment area was 80,700.64 km2, and the annual area of first abandonment peaked in 2004 at 7176.16 km2 and subsequently declined amid interannual fluctuations, with abandoned cropland concentrated on gentle slopes. Across five representative years, the mean FVC of land classified as abandoned each year rose from 0.273 in 2000 to 0.381 in 2020. These values reflect changes in pixel populations rather than the trajectory of a fixed set of fields. Among pixels mapped as abandoned in 2020, 86.07% showed increasing FVC over the entire study period, including 60.12% with significant increases. Extreme gradient boosting (XGBoost) analysis with Shapley additive explanations (SHAP) identified precipitation as the strongest predictor of spatial variation in the FVC change rate, accounting for 39.6% of the model’s relative importance. SHAP dependence patterns showed model-based transition points at approximately 395 mm of precipitation and 10 °C of temperature. These findings characterize vegetation-cover change associated with abandoned land and its environmental variation, whereas the full-period trends cannot isolate vegetation change caused by abandonment.