Spatial patterns of endemic plants in California

TitleSpatial patterns of endemic plants in California
Publication TypeJournal Article
Year of Publication2009
AuthorsThorne, JH, Viers, JH, Price, J, Stoms, DM
JournalNatural Areas Journal
Date Published2009
Keywordsendemism, flora, geodatabase, hotspots, Plant biogeography, range size

California endemic vascular plant range patterns were quantified using a flora-based geodatabase technique that combined species presence in geographic areas and elevation band occupation. Resulting species range maps were summarized by 228 geographic areas. Over 60% of the endemic species range size distributions were found to have range sizes less than 10,000 km2. The largest endemic taxon range was 275,749 km2, or 67% of the state. California endemic plants had different distribution patterns depending on the criteria used to portray them. California's Central Coast Ranges, Sierra Nevada foothills, high elevation Sierra Nevada Mountains, Channel Islands, San Jacinto Mountains, Napa and Lake Counties, Inyo Mountains, sections of the Mojave Desert, and San Bernardino Mountains were all identified as areas with unique endemic plant attributes. We compared endemic species richness between map units in zones that have similar topography and climate, and found that area only weakly correlated with species richness, suggesting other factors have stronger influence on endemism in continental California. The findings have implications for developing conservation plans that target endemic species. In particular, we identify areas of the state, previously de-emphasized, that deserve greater recognition based on the characteristics of their restricted endemic plants. Range distribution estimates produced from floral keys made digital proved effective in this study, an inexpensive approach that could be implemented in other regions of the world for which floras have been published.