SFPUC 2001 Alameda Watershed Management Plan

III. ENVIRONMENTAL SETTING AND IMPACTSE. NATURAL RESOURCESlow, shrubby arroyo willow (Salix lasiolepis), white alder (Alnus rhombifolia) and red alder(Alnus rubra) associated with California wax myrtle (Myrica californica), coyote brush(Baccharis pilularis var consanguinea), Douglas’ baccharis (Baccharis douglasii), Californiablackberry (Rubus ursinus), rush (Juncus sp.), and sword fern (Polystichum minutum).Central coast live oak riparian forest is a low evergreen sclerophyllous (i.e., hardened, toughleaves) riparian forest, usually with an open appearance, occurring in canyon bottoms andfloodplains. Coast live oaks (Quercus agrifolia) dominate and, often, an open understory withgrasses covers the ground. Associated species include mugwort (Artemisia douglasiana), coyotebrush (Baccharis pilularis var consanguinea), California blackberry (Rubus ursinus), poison oak(Toxicodendron diversilobum), and valley oak (Quercus lobata).White alder riparian forest is rooted in gravel or sand and supported along the banks of rapidlyflowing, perennial streams. White alder (Alnus rhombifolia) is strongly associated with big-leafmaple (Acer macrophylla). Understory plants include woody and herbaceous species such asarroyo willow (Salix lasiolepis), elderberry (Sambucus mexicana), sword fern (Polystichummunitum), chain fern (Woodwardia finbriata), bleeding heart (Dicentra formosa), and redlarkspur (Delphinium nudicale).Willow riparian forest (Salix spp.) occurs in moist canyons with perennial or at leastintermittent stream flow. Arroyo willow (Salix lasiolepis) grows to 20 feet in a large, dense,shrubby growth form, creating large thickets that provide valuable cover for birds and mammals.Willows also support a wide variety of insects that are fed upon by migratory birds, particularlywarblers and bush tits and other small insectivorous birds.Coast live oak riparian forest is quite close in habitat value to the oak woodlands. It is usuallyfound on ephemeral stream courses and is the driest of the all the riparian communities that occurin the Watershed. Coast live oak (Quercus agrifolia) is the dominant tree in this community,with an understory of western poison oak (Toxicodendron diversilobum), blackberry (Rubusursinus), mugwort (Artemisia douglasiana), coyote brush (Baccharis pilularis var.consanguinea), snowberry (Symphoricarpos mollis), and elderberry (Sambucus sp.).Coastal and Valley Freshwater MarshIn a number of places where streams and arroyos discharge to the reservoirs, sand and sedimentsuspended in the stream have been deposited in deltaic formations. These deltas are saturatedduring normal to high reservoir levels, and these areas support the growth of emergent wetlandvegetation. This natural community is defined as coastal and valley freshwater marsh.Freshwater marsh consists of a low-diversity assemblage of willows (Salix sp.), sedges (Carexspp.), and rushes (Juncus spp.). While the colonizing plants that grow in these marshes are notrare, the plant community has been disappearing in California due to increased pressure forconversion to agricultural and urban uses.NOP 96.223E: Alameda Watershed Management Plan III.E-6 ESA / 930385January 2001