Global shrub encroachment: cross-system impacts on natural spheres and socio-economy

Shrub encroachment is a widespread global ecological process that has intensified under the combined influences of climate change and human activities. Although its impacts have been widely documented, their integrated effects across natural and socio-economic systems remain insufficiently understood. By synthesizing 130 empirical studies published worldwide over the past two decades, this review examines the effects of shrub encroachment on atmospheric, hydrological, pedospheric, biological and socio-economic systems. Shrub encroachment reshapes carbon cycling, hydrological processes and nutrient dynamics through changes in vegetation structure, generating both ecological benefits and potential risks. While it may enhance carbon sequestration and soil stability under certain conditions, it can also affect water availability, modify biodiversity patterns and lower rangeland productivity, with potential implications for pastoral livelihoods. These divergent responses are influenced by climatic conditions, soil properties, shrub functional traits and ecosystem characteristics, resulting in pronounced spatial heterogeneity. Overall, shrub encroachment should not be simply categorized as ecosystem degradation or restoration, as its effects are highly context-dependent. Understanding these context-dependent responses is critical for developing tailored management strategies under global environmental change.