Laguna Watershed Knowledgebase

In a global context, Californian vernal pool vegetation is unique by the presence of such endemic genera as Lasthenia, Navarretia, Downingia, Plagiobothrys, Pogogyne, and Psilocarphus. Because of the dramatic decline over the last century vernal pool ecosystems attracted a lot of legislative and academic interest. However the diversity of vernal pool communities and unique characteristics of pools from different parts of California has not been well understood. During the past nine years, our team sampled more than 2500 plots in 800 pools throughout California, Oregon, and Nevada, among which 140 plots were located at 12 sites from Santa Rosa Plain (Todd Road, Wilkinson, Bravo Toro, Piner & Marlow, Wood Road, Maggi Site, Sam Jones Wetland Preserve, Horn Road, FEMA, Cooper, Mariposa Garden, and Haroutounian Site). Using multivariate techniques we analyzed distribution of plant species across geographical and ecological gradients. Three rare endemic species of Sonoma, Mendocino, and Lake Counties Lasthenia burkei, Blennosperma bakeri, and Limnanthes vinculans do not occur in most of the pools and we tried to understand how Santa Rosa Plain pools in which these endemic taxa are absent are different from pools from other regions of California. We found that many common vernal pool species such as Crassula aquatica, Lasthenia fremontii, Navarretia leucocephala, Plagiobothrys stipitatus, and Psilocarphus brevissimus are quite rare on Santa Rosa Plain. At the same time species such as Pleuropogon californicus, Juncus xiphioides are more common in pools on Santa Rosa Plain. This presentation summarizes information about diversity and regional peculiarities of Santa Rosa Plain vernal pool plant communities.