Dry-mesic old-growth oak forests in the eastern United States

Martin A. Spetich, Southern Research Station, USDA Forest Service, Hot Springs, AR, Michael A. Jenkins, Forestry and Natural Resources, Purdue University, West Lafayette, IN and Stephen R. Shifley, Northern Research Station (Retired), USDA Forest Service, Columbia, MO

Background/Question/Methods
Dry-mesic old-growth oak forests are widely distributed remnants across the eastern U.S and are expected to increase markedly in number and extent as older second-growth forests mature. However, we lack a comprehensive understanding of the character of these forests in terms of composition, diversity, dynamics and carbon sequestration. In this study, we synthesize unpublished data, personal communications, and existing literature to better define species, composition, biodiversity, structure, and extent of these forests and to fill gaps in our collective knowledge of this increasingly important forest type. These forests exist today due in part to a history of protected family owned forests, most of which are now in public ownership.
Results/Conclusions
Mean site tree density for trees ≥ 10 cm dbh ranged from 400-620 trees per ha. In the eastern part of the region most stand basal areas were >23 m2 per ha, compared to <23 m2 per ha in most of the western region stands. Overall woody species diversity was relatively low, with tree species per forest ranging from 5 to 18 and the most common species among stands being white oak (Quercus alba), red oak (Quercus rubra) and black oak (Quercus velutina) with greater importance of chestnut oak (Quercus prinus) in the southern Appalachian sites. Shrub and vine species per forest ranged from 1 to 10 with common species including poison ivy (Toxicodendron radicans), blueberries (Vaccinium spp.) and grapevines (Vitis spp.). Within the southern Appalachian Mountains, rhododendron (Rhododendron maximum) and mountain-laurel (Kalmia latifolia) were common. Herbaceous species per stand ranged from 4 to 51 with the highest richness occurring in a southern Appalachian oak-hickory forest. Maximum within stand age of large trees ranged from 137 to over 365 years. Density of standing dead trees ≥ 10 cm dbh ranged from 32 to 64 per ha and volume of coarse woody debris > 10 cm in diameter averaged 30.5 m3/ha.