 The national forest is home to some stands of old growth, including Port Orford cedar and Douglas fir in the Copper Salmon area.A 1993 Forest Service study estimated that the extent of old growth in the forest was  some of which occurs in the Red Buttes Wilderness.Blue oak, "Quercus douglasii", and Canyon live oak, "Quercus chrysolepis" occur in the Siskiyou National Forest.