Changes in Tree Canopy, Understory Vegetation, and Fuel Composition after 10 Years of Restoration Management in an Old-Growth Mountain Longleaf Pine Forest

Abstract

The Berry College Longleaf Pine Management Area (BCLPMA) harbors one of the few old-growth mountain longleaf pine (Pinus palustris) forests. Like many remnant longleaf pine forests, Berry College's stands have been fire-suppressed for decades. Since 2003, ∼160 ha of the BCLPMA has been managed using prescribed burns and herbicide injection of hardwoods with the goal of achieving an open, pine-dominated canopy, low duff, litter, and downed woody fuels, increased groundcover vegetation, and improved longleaf pine recruitment. Canopy tree structure was quantified using the point-quarter method in eight managed and five unmanaged stands in 2004 and 2014. Understory vegetation and downed woody fuels were estimated in a subset of these stands in 2003/2004 and 2015 using a plane-intercept method. Data from mountain longleaf pine stands in Alabama were included as external frequently burned and fire-suppressed references. Overall canopy and understory structure of managed stands has moved over time in the direction of frequently burned external reference stands. Longleaf pine basal area has been maintained and importance values have increased with management despite the loss of some canopy trees associated with duff smoldering after burning. Duff and litter levels have decreased substantially in managed stands, while understory plant cover (herbs, grasses, shrubs, vines, and small trees) has increased. Downed woody fuels, which have varied as a result of fire events, have generally dropped in managed stands, whereas longleaf pine recruitment has increased. Results show progress being made in restoring the vegetative structure to desired conditions and may inform analogous restoration projects throughout the mountain longleaf pine ecosystem.