Linking community structure and climate vulnerability in desert plant assemblages of southern California

Desert plant assemblages in southern California provide an opportunity to link patterns of community structure with climate-driven vulnerability in a rapidly changing environment. California sustains an exceptionally diverse flora of approximately 4300 plant species, with 31% identified as endemic. However, desert ecosystems remain comparatively understudied, and additional work is needed to better understand how plant communities may respond to ongoing climate change.

We compiled a large occurrence-only data set (~214,000 records) representing 1352 angiosperm species across the Coachella Valley, a heterogeneous region encompassing four desert ecoregions. Using spatial analyses, joint species distribution models, and ecological niche modeling, we evaluated patterns of community structure and projected changes in climatic suitability for representative species under future climate scenarios.

Plant diversity hotspots were strongly associated with steep elevational gradients, whereas cold spots were concentrated in lowland and environmentally extreme areas. Representative species exhibited strong co-occurrence patterns, capturing associations with 88% of annual species and 95% of perennial species. Invasive species occurrences were most frequent in highly populated areas across the study region. Future projections indicated substantial declines in suitable habitat for 90% of representative species, with many species predicted to shift northward within the Coachella Valley.

Declines in representative species under future climate scenarios are likely to be accompanied by concurrent reductions in many co-occurring taxa. These findings provide a community-level perspective on climate vulnerability in desert plant assemblages and highlight the value of integrating community structure and species distribution models to assess ecological responses to climate change.