Distribution of major forest species in southeastern Pennsylvania

Vegetation and environment of 82 forest stands in Lancaster, York, and Lebanon Counties in southeastern Pennsylvania were studied to determine the factors controlling the location of major forest species. Plants of some species were transplanted into 12 stands in which certain environmental factors were checked each week for two growing seasons. Thirty-six per cent of the 82 stands were the oak-hickory type, in which Quercus alba, Q. velutina, Q. coccinea, Carya ovalis, and C. tomentosa were among the leading dominants. Representatives of these oak-hickory forests have very low soil moisture for extended periods of time even in a year of normal rainfall. Quercus prinus was among the main dominants in 43% of the stands, representatives of which show excellent soil-moisture conditions even in a year of severe drought. Tsuga canadensis, Quercus rubra, Fagus grandifolia, Betual lenta, and Acer saccharum were among the leading dominants in 27% of the stands; representatives of these mixed mesophytic stands showed intermediate soil-moisture conditions. Tsuga canadensis reproduces only on steep slopes where litter is removed by erosion and where soil moisture is rarely very low. Fagus grandifolia reproduces largely by root sprouts. Quercus alba, Q. coccinea, Carya ovalis, and C. tomentosa reproduce poorly in mature stands, but reproduce much better in open and successional ones. Quercus prinus and Q. rubra reproduce well in mature stands and are judged to be climax species. Vegetation has not yet stabilized following the removal of Castanea dentata as a dominant species.