Shrub encroachment constrains precipitation-driven shifts in herbaceous biomass-diversity relationships

We screened 46 publications reporting both aboveground biomass and species richness in grasslands to conduct regression analyses of their relationship, including 25 studies on increased precipitation and 21 on reduced precipitation. Given the limited number of studies on precipitation manipulation experiments focusing on herbaceous communities in shrublands (only four relevant publications were identified), we integrated data from these sources with field measurements provided by Chinese Academy of Sciences (CAS) cooperative research stations to establish a comprehensive dataset to ensure robust data coverage. We compiled paired measurements of aboveground biomass and species richness for analysis from all 52 experimental sites across the globe. Most measurements were extracted directly from the main text or supplementary materials of the selected papers, while some values were digitized from figures using GetData Graph Digitizer (version 2.22; http://getdata-graph-digitizer.com/). In parallel, a long-term precipitation manipulation experiment was conducted at the Urat Desert and Grassland Research Station in northern China to further examine these dynamics within a desert steppe ecosystem.