Current and future patterns of vascular plant species richness across a forest–grassland–desert transect in East Asia.

Questions: Rapid climate change has profoundly altered the spatial distribution of terrestrial plants especially in arid and semi‐arid biomes. However, it remains poorly documented how climate shapes the current and future patterns of plant diversity within and across these vulnerable vegetation types. Location: Parts of Mongolia, southeastern Russia, and northern China (94.78°–126.78°E, 34.60°–54.27°N). Methods: Using a random forest model trained by a comprehensively compiled database on vascular plant species richness (i.e., the number of species within a defined plot area) and corresponding climate variables, soil conditions and vegetation types (forest, grassland, desert), we assessed the current pattern of vascular plant species richness across a typical forest–grassland–desert transect in East Asia. We further predicted future changes in vascular plant species richness under three climate scenarios (SSP1‐2.6, SSP3‐7.0, and SSP5‐8.5). Results: Vascular plant species richness generally showed a decrease from northeast to southwest across the transect, mainly explained by spatial variations in growing‐season precipitation and the minimum temperature of the coldest month. More than half of the transect area will likely experience a loss in vascular plant species richness in 2041–2070 under all three scenarios. The decrease in vascular plant species richness will likely occur in a smaller area under the low‐emission scenario (SSP1‐2.6). We also predict distinct changes in vascular plant species richness for different vegetation types, including a slight increase in forests but an overall decrease in both grasslands and deserts. Conclusions: Our findings suggest a dominant role of growing‐season precipitation in shaping the spatiotemporal patterns of vascular plant species richness across the forest–grassland–desert transect and highlight a risk of plant diversity loss in the regional dryland ecosystems in response to future climate change. [ABSTRACT FROM AUTHOR]