Drivers and impacts of changes in China’s drylands

Abstract

China has 6.6 million km2 of drylands that support approximately 580 million people. These drylands are at risk of desertification. In this Review, the changes observed in China’s drylands are synthesized, with a focus on their drivers and the effects of 13 large-scale land conservation and restoration programmes aimed at mitigating them, including the Three-North Shelterbelt Development Program and Grain for Green Program. After the implementation of the first large-scale restoration programme in 1978, 45.76% of China’s drylands experienced statistically significant land improvement or vegetation greenness, as identified by the Normalized Difference Vegetation Index. However, activities associated with restoration and conservation projects, such as afforestation, also impose substantial water pressure. Desertification thus remained prevalent during 1980–2015, with 11.43% drylands (especially in north-eastern and north-western drylands) experiencing land degradation or vegetation brownness. Drylands remain at risk of expansion owing to increasing aridity, particularly in semi-arid areas. Future trade-offs between the effects of CO2 fertilization and increased aridity on dryland vegetation cover are still poorly understood. Long-term experiments on the interactions between physical–chemical–biological processes across spatial and temporal scales, such as large-scale field surveys using standardized protocols, are needed to better manage drylands in China and globally. Global drylands are threatened by a combination of anthropogenic climate change and human activities, putting some locations at high risk of desertification. This Review details changes observed in the drylands of China, and the mitigating impact of large-scale restoration and conservation programmes designed to reverse them.