Ridgecrest Coastal Trail aew 04 17 2010

May 14, 2018   7:30 p.m.

Measuring the Health of a Mountain:                                                                                          Vegetation indicators for ecosystem health of Mt. Tamalpais
Guest Speaker: Andrea Williams

 Mt. Tamalpais in Marin County is a biodiversity hotspot, hosting over 1,000 plant taxa in more than 100 recognized communities—as well as the animals and physical processes that maintain this rich landscape. Determining whether Mt. Tam is “healthy” was the focus of a year-long process, selecting indicators and metrics and determining status and trend in relation to goals, with information gleaned from available sources such as vegetation maps, species lists, rare and invasive plant inventories and monitoring, research, and plant community monitoring. Initial indicators included grasslands, redwood forests, oak woodlands, maritime chaparral, serpentine barrens, Sargent cypress, riparian areas, and wet meadows; these communities represented high diversity, iconic or rare plants, and sensitivity to stressors such as climate change, disease, absence of natural fire regime, and presence of invasive species. After workshop feedback, shrublands were added. The overall species list, percent of non-native and invasive plants in the flora, and provisional list of likely extirpated species were also examined. Having repeated landscape-scale vegetation maps, up-to-date rare and invasive plant population data, and reasonably comprehensive historic and recent local floras were essential in the process.

Andrea Williams is the Vegetation Ecologist for Marin Municipal Water District, where she works to monitor and manage vegetation resources for the district.Big Carson Frog Day Lighting Project 012