Post-Disturbance Spruce-Fir Forest Stand Dynamics at Seven Disjunct Sites

Forests dominated by red spruce (Picea rubens Sarg.) and Fraser fir [Abies fraseri (Pursh) Poir.] occupy the highest elevations of the southern Appalachians. These forests have been severely impacted by logging early in this century and by the depredations of an exotic insect, the balsam woolly adelgid (Adelges piceae Ratz.). This study quantifies the structure and dynamics of logged and old-growth stands in the spruce-fir ecosystem and concentrates on sites that have received little previous research attention. A set of 39 permanent plots established in late 1984 was resampled in late 1991. Logged sites differed from old-growth stands by having greater mean annual diameter growth increments, higher rates of tree recruitment from the understory, and spruce age distributions skewed toward younger age classes. Greater densities of deciduous taxa and lower abundances of spruce in logged stands relative to uncut stands demonstrate that recovery from logging is a continuing process. These differences in stand structure and dynamics suggest that it will probably be decades before forest communities in logged sites resemble those in old-growth areas. Logged and uncut spruce-fir forests may also respond differently to future disturbances. Spruce mortality rates were not unusual compared to earlier research, and fir mortality rates were lower than those in earlier research, suggesting that the initial wave of adelgid-caused fir mortality is virtually complete.