Vegetation Resource Surveys in Muir Woods National Monument: Parking Alternatives Project

Steers,, Robert

In 2013, biological surveys focused on vegetation resources were conducted in the southern portion of Muir Woods National Monument (Muir Woods). These surveys were performed in conjunction with other environmental studies (reported elsewhere) to inform the exploration of automobile parking alternatives. These surveys included vegetation mapping, floristic analysis, and focused rare plant mapping. The purposes of this report are: 1) to describe the general setting of the study area, 2) to describe the methods used to capture its vegetative properties, and 3) to communicate the survey results. Muir Woods was established by the federal government in 1908 to protect one of the last remaining oldgrowth, coastal redwood (Sequoia sempervirens) forest in the San Francisco Bay Area. This old-growth forest occurs in the central and northern portions of the monument’s boundary and is the monument’s focal resource. The only public parking in the monument is located on the valley floor of Redwood Creek, south of the old-growth forest. Additional property along the valley floor of Redwood Creek and southeast of the existing parking area is relatively flat and could potentially be utilized to increase parking capacity. This area was the focus of the vegetative resource surveys reported herein. Past studies examining the vegetation of Muir Woods have mostly focused on the old-growth redwood forest and less attention has been given to other portions of the monument. Two past vegetation mapping projects that have covered at least a portion of the study area are the 1977 Muir Woods vegetation map (McBride and Jacobs 1978) and a larger mapping project based on 1994 aerial imagery that covered the coastal slopes of Marin, San Francisco, and San Mateo Counties (Schirokauer et al. 2003). The most recent flora of Muir Woods was compiled and certified in 2005 (IRMA 2005). Rare plant populations have been geo-referenced in Muir Woods (Michael Chassé, personal communication) but no rare plant surveys have occurred throughout the entire study area.