Valley Oak Restoration
One interesting and important component of the landscape on River Ridge Ranch is a series of Valley oak, Quercus lobata, corridors that run through the pastures. These corridors are located along runoff channels that drain Lumreau Mountain and its hillside natural springs. These Valley oaks are keystone species in the corridors and in the Central Valley in general. They form an important source of acorns for wildlife and provide the vertical structural component and shade that support stands of native grape (Vitis) and introduced and native blackberry (Rubrus) These oaks provide significant refuge, roosting and nesting habitat for thousands of insects which, in turn support hundreds of amphibians, reptiles, birds and mammals. The deep roots of the oaks allow surface precipitation and runoff to penetrate the soil and this water aids in providing late-season moisture to surrounding habitat. The same roots function in erosion-prevention.
Because the Valley oak corridors cross-cut the grasslands, they provide shade for grazing cattle as well. Indeed, cattle compete directly with native wildlife by trampling and direct interference.
The problem of competition is significantly worsened by the complete absence of recruitment of Valley oak in these corridors. In contrast, where cattle grazing has been reduced on the ranch, oak recruitment has returned.
We have improved oak recruitment, and thus begun to perpetuate the natural stands of Valley oak on River Ridge’s pastures, by fencing cattle out. In addition, we have a continuing program of restoration that removes invasive, exotic weed species and plants native grasses, trees and shrubs. Each year, we invite the public to join us in these efforts.