Examining the reversal of soil erosion decline in the hotspots of sandstorms: A non-linear ecosystem dynamic perspective

摘要

Land degradation neutrality (LDN) has been widely recognized as an important target to achieve goals for global sustainable development. Ecological restoration projects (ERPs) are considered a traditional approach to mitigate wind erosion by altering the structures and functions of the ecosystem. Thus, the efficiency of China's historical large-scale ERPs for wind erosion mitigation should be examined and optimized to better address this global environmental challenge. We assessed the change in wind erosion using a biophysical model and investigated the associated drivers identified. In addition, the efficiency of ERPs was examined by adopting the theory of nonlinear ecosystem dynamics. The erosion modulus significantly declined from 1990 to 2017, but this declining trend reversed since 2009. The structural equation model and related analyses revealed that the declining wind speed, wetting soil moisture, and vegetation greening substantially reduced wind erosion, while the reversal of declining wind speed around 2009 aggravated wind erosion, particularly in the northern Inner Mongolia Sandstorm Area. The relatively arid climate restricted vegetation restoration and further offset afforestation efforts, resulting in the transition of declining erosion modulus. From the perspective of non-linear ecosystem dynamics, a wet climate provides a crucial window of opportunity for ERP in drylands, while the window of risks due to dry and windy climates may extend the time required for a shift change after ERP and may postpone the stage change toward the LDN goal. Hence, climate-induced windows of opportunity and risks are crucial in identifying the time for initiating ERPs, and existing environmental conditions and critical thresholds should be carefully considered.