Impact and management of shrub encroachment are scale-dependent

Shrub encroachment is a major land use change in global grassland, affecting productivity and multiple ecosystem services. However, its impact on ecosystems is highly debated, as it varies largely across patch, landscape and regional scale, while shrub management is usually conducted on small scales only. Such mismatches in knowledge and management result in failures of encroachment control, which call for scale-dependent strategies in future management. Our study synthesizes the differential mechanisms under shrub encroachment from patch to regional scales. We further propose a framework to conduct shrub management with a top-down approach: (1) at the regional level, areas are prioritized for protection or improvement based on ecosystem service values and trade-offs; (2) at the landscape level, the focus shifts to identifying optimal shrub cover thresholds and spatial arrangements to improve landscape connectivity; (3) and at the patch level, management aims to maximize “fertile islands” effects by controlling key biotic and abiotic factors. By integrating the scale-dependent effect in shrub management, we can maximize management effectiveness and achieve a win-win outcome in grassland productivity and ecological restoration.