Evidence-based seed sourcing and restoration strategies for climate change-threatened California vernal pools

Climate change is driving more extreme and unpredictable precipitation patterns, which threaten the growth and survival of rare native plants. In California, significant amounts of public and private funds are being allocated towards the planting of native plants to restore habitats, but the market supply for native plants/seeds is small and sometimes cost-prohibitive. Despite the need for genetically diverse seeds that can adapt to environmental changes, evidence-based methods for seed sourcing remain underdeveloped, and there is a lack of consensus on what specific issues are preventing restoration practitioners from sourcing appropriate native seed for restoration projects. Our lab is developing evidence-based seed sourcing recommendations for two endangered native plants which are solely found in Californian vernal pools, rare ephemeral wetlands that have experienced 95% habitat loss in the state due to human land development since European colonization. We conducted a field experiment planting seeds sourced from different populations/years into created vernal pool wetlands. Our preliminary results show greater growth and reproductive rates at higher planting elevations in the pools. Seed source had some impacts on germination rates, growth, and reproduction, with one of the two species showing increased growth and reproductive output from local seeds when grown under favorable precipitation conditions. Additionally, using an anonymized web survey of CA restoration practitioners, our lab characterized the financial and logistic barriers to adopting evidence-based seed sourcing practices. We found that grant timelines are much shorter than seed production timelines, creating a supply and demand disconnect, and that an overemphasis on local seed sourcing in the restoration ecology field has led to prioritization of local seeds above sourcing for genetic diversity and climate adaptive traits.These are some of the initial projects being investigated by our new Cal Restoration Ecology research lab in the Biology Department at University of the Pacific. Through our work, we are producing data that can support evidence- based strategies for restoration seeding, and are identifying key barriers to evidence based restoration that can be addressed at the policy level in partnership with conservation non-profit organizations.