 An unusual characteristic of these forests is the high content of undisturbed prehistoric bunch grass understory, testifying to the absence of historic grazing or other agriculture.Besides the riparian habitat, plant communities include California oak woodland, Douglas fir forest, chaparral, grassland and marsh.The dominant plant community is the oak woodland, which has a canopy of coast live oak, Garry oak, black oak, Pacific madrone, bigleaf maple and California laurel.