Oaks

Because of their widespread distribution, oaks play an significant ecological role in many forest communities. Of the 90 forest-type covers described in the United States and Canada, oaks are an important element in 64. and include both evergreen and deciduous species. Some of the more important species in North America include the northern red oak (Q. rubra), the black oak (Q. velutina), and the white oak (Q. alba) in the east. The coast live oak (Q. agrifolia), the gambel oak (Q. gambelii), and the wayleaf oak (Q. undulata) are most widespread in the western region.

Most species are limited to either the eastern or western regions of the continent, with chinkapin oak (Q. muehlenbergii) and shin oak (Q. havardii) the only species to bridge the gap through the prairies. Due to the spread of development pressures and conversion of rangeland into housing and commercial uses, there are now several species of oaks facing serious decline. Of these, the Oglethorpe oak (Q. oglethorpensis) in Georgia, the valley oak (Q. lobata), blue oak (Q. douglasii), and Englemann oak (Q. engelmanii) in California and several species with limited ranges in Texas, New Mexico, and Arizona are considered either rare, threatened, or endangered.

Contributing to this problem is the lack of regeneration of many oak species. For a wide variety of reasons, including changes in understory vegetation, soil compaction, damage by grazing animals, changes in fire frequency and associated forest species, natural recruitment of new trees is limited in many areas. Mixed age stands are not as common as single age stands in many areas. More intensive management to provide light openings, reduce soil compaction, and eliminate competitive species is slowly beginning to turn this trend around. Prescribed burning to restore a more natural fire ecology is being done in many areas. The thick bark of oaks is particularly adapted to withstand forest fires and they can resprout from the root crown if the tree is burned.