Objective Arid areas are highly vulnerable to global climate change. Plant species play an important role in maintaining the stability of dryland ecosystems. Research on species distribution patterns of different growth forms in arid regions, as well as their influencing factors is crucial for formulating effective strategies for biodiversity and vegetation conservation.

Method Here, we took Xinjiang in northwestern China as a case to investigate the diversity patterns of different growth forms of seed plant species and their relationship with environmental factors. We established the geographic distribution database with the resolution of 50 km by 50 km of 3716 native seed plants in Xinjiang. By integrating generalized linear model and hierarchical variation partitioning, we identified the relative importance of current climate (mean annual temperature (MAT), mean annual precipitation (MAP), mean temperature of the coldest quarter, precipitation of the driest quarter, temperature seasonality, and precipitation seasonality), paleoclimate (MAT anomaly, MAP anomaly, MAT changing rate, MAP changing rate) and habitat heterogeneity (elevation range, MAT range, MAP range) in shaping the species diversity of different growth forms (trees, shrubs, and herbs) among seed plants.

Result (1) The results revealed that areas of higher richness of seed plant diversity, as well as the diversity of trees, shrubs, and herbs were predominantly concentrated in mountainous regions in northern Xinjiang. (2) The diversity of species across different growth forms (trees, shrubs, and herbs) was primarily influenced by contemporary climate variables, particularly those related to precipitation, followed by habitat heterogeneity, whereas the effect of paleoclimate was the least significant. (3) The relative importance of environmental factors in shaping the spatial pattern of plant species diversity was most evident in the order of herbaceous plants, shrubs and trees. Among these, the factors explaining the highest proportion of diversity variation were precipitation seasonality for trees, and the precipitation of the driest quarter for shrubs and herbs.

Conclusion These findings demonstrate that plants of different growth forms have significant differences in their responses to environmental factors, which should be integrated into the framework of biodiversity research. Furthermore, the results underscore the critical influence of precipitation on plant diversity in arid regions, offering theoretical support for the conservation and management of fragile arid ecosystems.