SFPUC 2001 Alameda Watershed Management Plan

III. ENVIRONMENTAL SETTING AND IMPACTSE. NATURAL RESOURCESa dense, often impenetrable canopy. It is usually found on dry, rocky, east-facing steep slopesand exposed ridges with little soil. Species in this community include scrub oak (Quercusdumosa), chamise (Adenostoma fasciculatum), western poison oak (Toxicodendrondiversilobum), manzanita (Arctostaphylos sp.), and ceanothus (Ceanothus sp.).Woodland and Riparian Forest CommunitiesWoodland communities in the Watershed are composed of mixed evergreen forest / coast liveoak woodland, valley oak, blue oak woodland, and sycamore alluvial woodlands. Woodlandareas constitute about 8,700 acres (22 percent) of the Watershed. Most forest communities foundwithin the Watershed are riparian forest communities. Riparian forest communities that occur inthe Watershed include central coast arroyo willow riparian forest, willow riparian, white alderriparian forest, central coast live oak riparian forest, and coast live oak riparian forest.Mixed evergreen forest / coast live oak woodland is found on moist, well-drained slopes withcoarse soils. This community occurs on the steep northeast-facing slopes above San Antonio andCalaveras Reservoirs and along Alameda Creek above the dam. Species that make up thiscommunity include coast live oak (Quercus agrifolia), madrone (Arbutus menziesii), poison oak(Toxicodendron diversilobum), and California bay (Umbellularia californica). Some associatedplant species include big-leaf maple (Acer macrophyllum), toyon (Heteromeles arbutifolia), andCalifornia blackberry (Rhamnus californica).Valley oak woodland (Quercus lobata) is abundant in the vicinity of San Antonio and CalaverasReservoirs. This community is sparsely distributed within non-native grassland and has an opencanopy that seldom exceeds 30-40 percent cover. In the vicinity of San Antonio Reservoir,valley oaks occur near the reservoir where deep, well drained alluvial soils are present andindividual trees are likely to be rooted in permanent sources of water. Many large specimens arealso found along the top of Poverty Ridge, between Calaveras Reservoir and Arroyo Hondo. Inthe Watershed, this community is found at elevations ranging from 230 feet to 3,000 feet.Blue oak woodland (Quercus douglasii) is sparsely distributed. Blue oak woodlands grow onthe northeast-facing steep slopes where the soil is either dry or well drained. Within theWatershed, they occur along Alameda Creek, Arroyo Hondo, and Williams Gulch.Sycamore alluvial woodland is an open to moderately closed, winter deciduous broad-leafedriparian woodland. It occurs in braided depositional channels of intermittent streams, usuallywith cobblestones or boulder type substrate; San Antonio Creek is a prime example. Commonspecies in this community are California sycamore (Plantanus racemosa), California buckeye(Aesculus californica), blue elderberry (Sambucus mexicana), and occasional cottonwoods(Populus fremontii) and valley oaks (Quercus lobata). The understory is made up of introducedgrasses or mule fat (Baccharis salicifolia). In general, this community is restricted to the SouthCoast Range; Alameda County is the northernmost extent of its range.Central coast arroyo willow riparian forest occurs in moist ravines and canyons withperennial or at least intermittent stream flow. Species characteristic of this community includeNOP 96.223E: Alameda Watershed Management Plan III.E-5 ESA / 930385January 2001