Graham Creek - Ecology

Ecology

The riparian forests along Graham Creek and its tributaries are quite verdant and have a considerable canopy height, due to the eastern exposure of the relatively steep Sonoma Mountain, which favors forests to outcompete grassland, and whose moist climate nurtures lush tree growth. The most common plant community is the California oak woodland, which has a canopy of coast live oak, Garry oak, Black oak, Pacific Madrone, Bigleaf maple and California laurel. In some of the steeper, cooler riparian zones there are also small groves of Coast redwood, Sequoia sempervirens. In these oak woodlands, the dominant understory plants are toyon, blackberry, western poison-oak and in occasional drier patches some coyote brush. Animals commonly observed include Black-tailed Deer, gray squirrel, raccoon, skunk and opossum. Less frequently bobcat and mountain lion are seen. There is abundant birdlife including the scrub jay, Steller's jay, Acorn woodpecker and junco. Because of the rich soils and mild climate, there are significant sized vineyards at elevations up to 1700 feet (518 meters) on the northeast flanks of the mountain, positioned like mosaics in a patchwork of mostly oak forest; these grapes contribute to some premium varietal wines, some of which are marketed as premium Sonoma Valley appellations.

Anadromous fish movements in Graham Creek have been studied, although even more extensive research has been conducted of the mainstem Sonoma Creek. These investigations have demonstrated a historical decline in spawning and habitat value for these species, primarily due to sedimentation and secondarily to removal of riparian vegetation since the 19th century. Because of the steep slopes of Graham Creek, the removal of vegetative shading was not as severe as certain other tributaries of Sonoma Creek such as Carriger Creek and Yulupa Creek, where grazing animals could easily wander into the creekbeds of lower reaches. In the case of Graham Creek, relatively steep side canyons and stream gradient commence almost immediately above the confluence with Sonoma Creek.