California is a recognized biodiversity hotspot including over 5,700 native species and one-third being endemic. It’s rapidly growing population coupled with housing shortages, increased resource demands, and changing climates has led to regional planning assessments to streamline the ability to meet such pressing and complex demands. To ensure that plants and their habitats are adequately represented and protected, tools are needed to identify the most important areas for sustaining rare and threatened plant species, rare and threatened vegetation associations, vegetation important to indigenous peoples, and areas of high plant biodiversity. An assessment of available datasets representing each of these categories was performed in California’s Central Valley Ecoregion. This region was selected as a test case due to increasing demands for housing, ground water, and renewable energy development, and an abundance of relevant resource datasets. Data for rare vascular plant species occurrences, rare vegetation types (using the US National Vegetation Classification standard), evolutionary survival time for vascular plants, soil, geology, and native plant collection records were combined with regional expert input into a 1km2 cells, forming a grid over the study region using ArcGIS software. This master datafile was input to a relativistic model structure built using the Environmental Evaluation Modelling System (EEMS) developed by Conservation Biology Institute. A 5-mile buffer was used around the study region to mitigate artificial edge effects. Results were grouped into 10 quantiles with the top 10% selected out for evaluation as potential Important Plant Areas in the California Central Valley Ecoregion.
Results/Conclusions
Initial model outputs highlight wetland complexes, riparian corridors, former lake beds, the Sutter Buttes, and terraces lining the eastern edge of the valley floor as having highest conservation value for vascular plant biodiversity in California. Due to the highly modified nature of the landscape, these represent remaining areas within the California Central Valley Ecoregion which have not yet been converted to housing, renewable energy, or intensive agriculture. This analysis presents a planning tool that can be used to efficiently target conservation activities where they will have the greatest impact for advocacy, conservation planning, and/or development of land management policies and regulations. Next steps include revising the model structure based on comments from an Important Plant Areas Technical Advisory Committee and regional experts and performing a secondary analysis on threat risk to subsequent outputs delineated as important plant areas for each ecoregion across California.