Field Update: Santa Susana Mountains

By Kendra Sikes and Julie Evens

This spring, the CNPS Vegetation Program spent three weeks surveying the vegetation of the Santa Susana Mountains, an area that covers almost 150,000 acres.  The mountain range is in Southern California between the Santa Clara River to the north and Simi Valley to the south.  Its highest point is Oat Mountain at 3,750 ft. elevation.  The city of Santa Clarita along Interstate 5 is at its eastern edge, and Santa Paula is near its western edge.  Even locals may not be aware of this range, beyond the presence of the Santa Susana Pass along Highway 118 between Simi Valley in Ventura County and the San Fernando Valley in Los Angeles County.

We sampled more than 30 vegetation alliances in this diverse area, including:

• bigcone Douglas-fir (Pseudotsuga macrocarpa) forest
• valley oak (Quercus lobata) and coast live oak (Q. agrifolia) upland and riparian woodlands
• scalebroom (Lepidospartum squamatum) alluvial scrub
• cactus (Opuntia littoralis) scrub
• arroyo willow (Salix lasiolepis) scrub
• hoary leaf ceanothus (Ceanothus crassifolius) chaparral, and
• white sage (Salvia apiana) scrub.

This sampling is the first step toward creating a vegetation classification and a fine-scale map of the area’s plant communities.

This vegetation map will provide baseline information for assessing wildlife habitats, gauging change over time, guiding management efforts, and long-term conservation strategies. The US Fish and Wildlife Service is providing funding for the project.

Those interested in rare plants may have heard of the Santa Susana tarplant, Deinandra minthornii (synonym Hemizonia minthornii), which is state-listed as rare and CRPR 1B.2, named for the mountain range where it is found. It is also home to the two-striped garter snake (Thamnophis hammondii), Blainville’s horned lizard (Phrynosoma blainvillii), coastal California gnatcatcher (Polioptila californica californica), least Bell’s vireo (Vireo bellii pusillus), among many other birds and wildlife species, and serves as a critical linkage between the Santa Monica Mountains to the south, the San Gabriel Mountains to the east, and the Los Padres National Forest to the north.

Kendra Sikes is a vegetation ecologist
with the CNPS Vegetation Program. 

Julie Evens is the
CNPS Vegetation Science Program Director.

Learn more about the Vegetation Program and how you can help!