Oak Savannah
31.57 acres of Oak Savannah occur in the north central sections of the Atascadero Creek watershed. Oak Savannah differs from Oak Woodland in that the branches of adjacent trees do not touch in savannah. It is not clear whether Oak Savannah is a natural habitat type on San Marcos Foothills or one shaped by the activities of humans and cattle. Due to grading by a previous land owner and the frequent concentration of cattle beneath oaks, the soils are depleted and native vegetation is lacking. Replacement of oaks through regeneration in Oak Savannah does not occur on San Marcos Foothills.

Nevertheless, the ecological expression of Oak Savannah on San Marcos Foothills is strong for arboreal species. The openness supports birds such as Lark Sparrow, Phainopepla, and Lesser Goldfinch—species generally not found nesting in and near dense woodland or riparian settings. Perching birds of prey (Red-tailed Hawk, American Kestrel, and White-tailed Kite) often use the Savannah or the edges of oak habitats because they provide stationary posts for foraging over the more open grasslands they prefer.

Under our management scenario, Oak Savannah could continue to be used by cattle for weed control. However, oak replacement should be undertaken by excluding cattle around oak saplings. [Policies Gen-1.2, 1.4; Eco-2.5, 2.6]

Oak Woodland
2.03 acres of Oak Woodland occur along Atascadero Creek and northern Cieneguitas Creek. Oak Woodland differs from the other two oak habitats in that the tips of the outermost branches touch, providing a continuous canopy for the most part, and it lies outside the riparian zone. Yet both occurrences of Oak Woodland at San Marcos Foothills are near wetlands. (See Map 5, Wetland Areas.)

In the Oak Woodland along southern Atascadero Creek, California Walnut has been hybridized, probably deliberately, with English Walnut to create an enormous individual tree and several smaller individuals showing traits of both parental forms. A spring emerges from the steep west-facing slope not far below the top of the inholding (see Map 5, Wetland Areas). Two very rare wetland plants, Low Clubrush and Water Pimpernel, are present along the road cut that exposes the spring. Arroyo Willow and Red Willow follow the spring down to Atascadero Creek. Lateral to the spring, the understory is poorly developed due in part to the shade of the dense oak canopy. This woodland and spring was clearly important to Native Americans as it is immediately adjacent to the largest and most well-known archaeological site on the property.

In northern Cieneguitas Creek, the Oak Woodland is east-facing and it abuts dense Chaparral on and north of San Marcos Foothills. Again, the canopy restricts some undergrowth but other vegetation includes ferns, Hummingbird Sage, Bush Monkey-flower, and California Figwort. Cattle have affected the understory here.

Species using Oak Woodland include Purple Finch, Acorn Woodpecker, Nuttall’s Woodpecker, Ash-throated Flycatcher, Western Wood Pewee, Pacific-slope Flycatcher, Oak Titmouse, Hutton’s Vireo, Black-headed Grosbeak, Anna’s Hummingbird, Bushtit, Violet-green Swallow, White-breasted Nuthatch, Wrentit, Merriam’s Chipmunk, and Dusky-footed Woodrat. Information on amphibians, bats, and small mammals that might use Oak Woodland is generally lacking. [Policies Gen 1.1, 1.2, 1.4; Water 3.7; Rim-4.2]

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