| Popis: |
Woody plant encroachment (WPE) has been widely studied, yet the spatiotemporal pattern of global WPE and its drivers remain unclear. Here, based on long-term remote sensing observations, we investigated the spatiotemporal dynamics of global WPE from 2001 to 2020 and assessed the contributions of the changes in main environmental factors. We found a significantly increasing WPE trend (0.25% a−1, P < 0.01), resulting from a pronounced gain and a slight loss in woody vegetation (0.29% a−1 and 0.04% a−1, P < 0.01, respectively). The global pattern of trends was characterized by large spatial heterogeneity, with 82.95% of areas experiencing an expansion in woody plants. We then used a random forest model incorporating key environmental factors to investigate the complicated driving mechanisms of global WPE. Our results identified warming and elevated CO2 concentrations as the primary drivers of global WPE dynamics, given their substantial contributions to WPE trends (0.66% a−1 and 0.32% a−1, P < 0.01, respectively). Changing precipitation regime was crucial, but its contributions to the WPE trends showed great spatial heterogeneity and offset each other, ultimately leading to a smaller contribution (0.09% a−1, P < 0.05). In contrast, varying radiation and burned areas had minimal effects (−0.04% a−1, P > 0.05 and −0.03% a−1, P < 0.01). We also found that the effects of local factors, such as human activities and natural disturbances, on WPE were non-negligible (0.07% a−1, P < 0.01). Our study provides a comprehensive picture of the spatiotemporal dynamics and drivers of global WPE, enhancing our understanding of biome transitions in response to environmental changes. |
