UC Merced

Wetlands rank among the world's most imperiled ecosystems with the highest rates of habitat destruction, degradation, and loss of biodiversity. This is especially true for ephemeral vernal pool wetlands found in the Great Central Valley of California, USA, a region impacted by urbanization and high agricultural productivity. California vernal pools are small isolated ephemeral wetlands dominated by annual plant communities and represent centers of endemism and hotspots of native plant biodiversity. These taxonomically rich ecosystems are also highly threatened as most of the historical vernal pool habitat has been destroyed by agriculture and urban development and, consequently, host to numerous threatened and endangered plant species. Despite extensive conservation efforts, knowledge gaps remain about the ecological and evolutionary processes essential for maintaining these plant communities.

For my dissertation, I investigated the ecological dynamics and adaptive potential of the vernal pool annual plant Limnanthes douglasii ssp. rosea (meadowfoam), and assessed the utility of environmental DNA (eDNA) metabarcoding for monitoring rare and endemic vernal pool plant species. In the first chapter, I conducted a multivariate and ecological descriptive study to characterize habitat and morphological variation of meadowfoam plants occurring in different soil types associated with remaining vernal pool habitats in California. I found significant effects that environmental attributes and soil types strongly influence plant morphology, which could be essential for targeted conservation strategies. In the second chapter, I conducted a greenhouse experiment to explore plant-soil interactions and meadowfoam's adaptive potential. I found significant soil-driven effects on plant performance, attributed to differences in soil quality and adaptive potential of meadowfoam, highlighting the importance of preserving diverse soil habitats to maintain genetic diversity and species resilience. For my third chapter, I compared floristic surveys to plant DNA sequenced from vernal pool soil samples to assess the efficacy of eDNA as a biomonitoring tool of endemic and endangered vernal pool plant species. Here, I found eDNA effectively tracks a wide range of plant species, including rare and endemic vernal pool indicator species, with detection frequencies closely linked to plant abundance and ecological niche. This provides valuable insights for managers on the uses and limitations of eDNA as a monitoring tool in ephemeral ecosystems.

Collectively, these findings contribute valuable knowledge for the conservation and restoration of vernal pool ecosystems, informing management practices aimed at preserving these unique and threatened habitats. Importantly, this work supports local conservation efforts by prioritizing management strategies of particular vernal pools associated with high biodiversity or threatened species for conservation.