Ecological and genetic consequences of habitat mitigation on an endangered California vernal pool plant: Sebastopol meadowfoam (Limnanthes vinculans)

The Santa Rosa Plain in Northern California is a region that provides unique vernal pool wetland habitat to many federally and state-listed endangered species. In an effort to mitigate for severe vernal pool habitat loss over the last 30 years, state regulations have mandated the construction of artificial vernal pool habitat. Currently, vernal pool wetland construction involves the movement of soil inoculum without consideration of ecological and genetic processes that may affect species persistence. My thesis examines the consequences of habitat creation on the abundance, distribution, and genetic structure of Sebastopol meadowfoam (Limnanthes vinculans), a highly endangered vernal pool endemic plant. Vegetation and ecological surveys indicated that the distribution and abundance of this species within wetlands can vary dramatically among wetland sites, and that created vernal pools generally do not support highly productive populations that characterize a subset of the natural wetland features. Genetic analysis of neutral microsatellite variation revealed significant patterns of spatial genetic structure in L. vinculans emerged across local (within-pool) and geographic (among-pools) scales, with elevated levels of gene flow evident among the created pools compared to natural remnant pools. Finally, results from a controlled growth chamber experiment documented strong negative effects of soil compaction on the survival, growth and reproductive output of L. vinculans, suggesting that the use of heavy construction equipment to create vernal pool habitat topography may contribute to poor population establishment in mitigated pools, and may ultimately limit the ability of translocated populations to develop a sustainable seed bank. Collectively, these results can provide valuable information that may significantly alter the current conservation strategy for this species, and emphasize that without a basic understanding of species-specific responses to habitat creation, uninformed mitigation and management practices may undermine the long-term conservation of endangered vernal pool plant species