Restoration of northwest Florida sandhills through harvest of invasive Pinus clausa

Across much of the southeastern U.S.A., sandhills have become dominated by hardwoods or invasive pine species following logging of Pinus palustris (lo ngleaf pine) and fire suppression. At Eglin Air Force Base where this study was conducted, Pinus clausa (sand pine) has densely colonized most southea stern sandhill sites, suppressing groundcover vegetation. The objectives of this study were: to determine if suppressed groundcover vegetation recover s following the removal of P. clausa; to compare species composition and ab undance in removal plots with that in reference, high quality sandhills; to test the assumption that recolonization by P. clausa seedlings decreases w ith proximity to the centers of removal plots; and to measure the survival of containerized P. palustris seedlings that were planted on P. clausa remo val plots. One year post-removal (1995), the number of plant species decrea sed by 50%, but then increased by 100% from 1995 to 1997, followed by a sma ll reduction in 1998. The number of plant species was greater in reference plots than in removal plots prior to 1997. Eighty-five percent of the origi nal species were recorded 4 years post-harvest in removal plots. Shrubs and large trees remained at low density after harvest. Densities of graminoids , legumes, other forbs, woody vines, and small trees increased after harves t. Plant densities of all life forms, except woody vines, were greater in r eference plots than in removal plots. The density of recolonizing P. clausa seedlings 2-4 years post-harvest significantly decreased with increasing p roximity to the centers of removal plots. On average, 80% of planted P. pal ustris seedlings survived their first 2 years. Harvest of P. clausa followe d by fire and the planting of P. palustris is a reasonably effective restor ation approach in invaded sandhills. However, supplementary plantings of so me herbaceous species may be necessary for full restoration.