Changes in vegetative structure in the first decade of restoration management in an old growth Mountain Longleaf Pine forest
The Berry College Longleaf Pine Management Area (Floyd County, GA) harbors one of the few remaining old-growth Mountain Longleaf Pine (Pinus palustris L.) forests. This forest type extends into the Piedmont and Ridge and Valley provinces of northwestern Georgia and northeastern Alabama. Like most remnant longleaf pine forests, Berry College’s stands have been fire-suppressed for decades. Since 2003, about 160 ha of old-growth forest has been managed using low-intensity prescribed burns and herbicide treatment of hardwoods. This study assesses progress made toward restoring an open, pine-dominated canopy, with low duff, litter, and other fuels, increased groundcover plants, and a stablized longleaf pine population. Tree community structure was quantified using the point-quarter method at +/-25 random points in each of eight managed and five unmanaged stands in 2004 and 2014. Other vegetative variables (litter, duff, understory plant cover, and pine seedlings) were measured in 2 m2 plots in a subset of stands in 2004/05 and 2013/14. Downed woody fuels, were estimated during the same time periods using a plane-intercept method. Data from old-growth stands in Alabama (Talladega National Forest and Mountain Longleaf Pine National Wildlife Refuge) were included as external frequently burned (three stands) and fire-suppressed (one stand) references.
Results showed that longleaf pine basal area has decreased in managed areas (mostly as a result of deaths associated with duff smoldering after prescribed burning). Nevertheless, managed stands were vegetatively similar to frequently burned external reference stands. For example, ordination of tree community data showed managed stands moving over time in the direction of frequently burned reference stands. Longleaf pine importance values have risen relative to hardwoods and other pines, and longleaf pine seedling recruitment is now evident throughout managed stands. Duff and litter levels have decreased substantially over time, while understory plant cover has increased. Various categories of woody fuels, while varying over time as prescribed burning both consumed and produced dead plant matter, have dropped overall in managed stands. In contrast, unmanaged stands remained vegetatively similar to their condition when first surveyed in 2004, and were similar to the fire-suppressed external reference stand. Results show progress being made in restoring the vegetative structure to desired conditions and in facilitating a self-regenerating longleaf pine population. Restoration work at this site may serve as a template for analogous restoration projects throughout the Mountain Longleaf Pine ecosystem.