Dendroecological analysis of a mature loblolly pine-mixed hardwood forest at the George Washington Birthplace National Monument, eastern Virginia

The composition, structure, and dendroecology of a mature pine-hardwood forest was studied at the George Washington Birthplace National Monument, eastern Virginia. Loblolly pine, sweetgum, holly, blackgum, and several oak species dominate the forest. Blackgum trees dominated recruitment from 1840 to 1900, based on current age structure. All other tree species are less than 100 years old. A compilation of major and moderate radial growth releases revealed multiple disturbance events in most decades from 1870 to 1990. A dramatic increase in the radial growth of blackgum occurred in the late 1880s, probably in response to selective logging of pine and hardwood timber species. This disturbance stimulated the recruitment of blackgum followed by loblolly pine and other hardwood species. A decline in blackgum recruitment occurred during the 20th century. The existing loblolly pine range in age from 64 to 105 years old, and this species stopped recruiting in 1935. The loblolly pine standardized (ARSTAN) chronology was positively correlated, and blackgum negatively correlated, with current and previous year temperatures. There were no correlations with Palmer drought severity index or precipitation. Seedlings and saplings of all species are scarce, with the exception of holly, a highly shade tolerant, understory tree species. Loblolly pine trees in the overstory may exhibit future declines due to their relatively short longevity, insect attack, and windthrow. Given current conditions, the future stand composition most certainly will contain less loblolly pine and more hardwoods, including sweetgum, blackgum, and holly.