Oak Forest. Forest communities usually dominated by chestnut oak and northern red oak are common on less disturbed upland sites at Catoctin Mountain Park and Harpers Ferry National Historical Park. Several other species of trees, including white oak, hickory and sassafras, tend to occur along with the two oaks, and witch hazel is often present as a tall shrub. These forests represent the best type of habitat in which to find macrofungi, since the majority of the trees present form ectomycorrhizal associations and there is usually abundant dead wood on the forest floor.