Supporting Tribal resilience in Southern California through plant vulnerability assessment

Abstract In Southern California, Tribal communities codeveloped research supporting Tribal stewardship and climate adaptation planning by conducting a broad assessment of 50 plant species' exposure to future climate change and land use change. The research objective was to understand shifts in biodiversity that may occur in the near future under global change scenarios. We paired species distribution modeling to measure climate exposure with sensitivity and adaptive capacity ranking based on the life‐history and fire‐response characteristics of each plant species. Our findings revealed a major impact of high‐emission scenarios on species' threat categories. We projected average habitat loss of 26% under high emissions and 17% under moderate emissions. Nearly half of the species would shift into higher threat categories based on projected habitat loss under high‐emission scenarios. The vulnerability assessment varied across plant communities. The piñon‐juniper community may experience significant declines, while conifer forest species would show higher resilience and adaptive capacity. Oak ( Quercus spp.) and riparian species generally showed resilience, while desert species were more sensitive. California juniper ( Juniperus californica ) and Joshua trees ( Yucca brevifolia ) were highly exposed and vulnerable to environmental stress. Deer grass ( Muhlenbergia rigens ) and California ephedra ( Ephedra californica ) showed higher resilience despite projected habitat losses. The assessments also predict that several desert species, including the teddy‐bear cholla ( Cylindropuntia bigelovii ), buckhorn cholla ( Cylindropuntia acanthocarpa ), and palo verde ( Parkinsonia florida ), have low exposure to habitat loss but have high sensitivity and low adaptive capacity, based on their traits. Our vulnerability assessment provides information on the relative magnitude of global change versus other threats. This assessment supports the development of strategies to steward ecosystems, address vulnerable plant populations, and advance Tribally led climate adaptation planning.