Desertification vulnerability under accelerated dryland expansion

• Published in: Land degradation & development 2023-04, Vol.34 (7), p.1991-2004
• Main Authors: Sun, Chuanlian, Feng, Xiaoming, Fu, Bojie, Ma, Shijun
• Format: Article
• Language: English
• Subjects: Arid lands; Arid zones; Aridity; biome shift; climate change; Decline; Degradation; Desertification; desertification vulnerability; Ecosystem management; Ecosystem structure; Ecosystems; Environmental security; Evapotranspiration; Greenhouse gases; Land degradation; Population growth; Soil fertility; Soil structure; threshold; Vegetation
• ISSN: 1085-3278; 1099-145X
• DOI: 10.1002/ldr.4584

Given accelerated dryland expansion, studies on aridity‐driven desertification are of great importance for advancing our understanding of land degradation mechanisms and developing possible mitigation measures. However, the mechanism by which increased aridity drives ecosystems toward desertification and the impacts of aridity on desertification vulnerability both in space and over time remain unclear. Here, we collected eight key ecosystem structure/functioning data (including soil, vegetation, and animal) for threshold identification using piecewise linear models, and then linked them to biome shifts to explore the process of aridity‐driven desertification. The results show that ecosystems along aridity index (AI, 1 − precipitation/potential evapotranspiration) gradients experience three vulnerable stages featuring different threshold and biome responses: a low vulnerability stage (AI: 0.5–0.65; mainly featuring a soil fertility loss and a forest decline), a moderate vulnerability stage (AI: 0.65–0.75; mainly featuring accelerated non‐forest vegetation degradation) and a high vulnerability stage (AI: 0.75–1; mainly featuring rapid overall land degradation). According to further simulations, areas with low to high vulnerability account for 31% of the global terrestrial area, which is projected to increase by 18.8% (21.2%) by the end of the 21st century under the greenhouse gas emission scenario SSP2‐4.5 (SSP3‐7.0). Given increased vulnerability and population growth, Africa and East Asia are exposed to great desertification risk and ensuing contradiction between humans and land. These findings can provide a theoretical and practical reference for ecosystem management and policy development, which are critical for dryland ecological security and human welfare in areas threatened by desertification.