A Denroecological Analysis of Disturbance of Remnant Pinus Palustris, Southeastern Virginia

Abstract

Pinus palustris Miller (longleaf pine), in Virginia, is at the northernmost extent of its range. During presettlement times, this species occurred throughout the Piedmont and Coastal Plain of Virginia in pure and mixed stands, covering 607,000 hectares. This forest type has since been reduced to 81 hectares or 0.01% of its former range. Around 5,000 individual Pinus palustris remain on six sites in the coastal plains. Seacock Swamp and Everwoods are both sites known to have naturally regenerated Pinus palustris native to Virginia occurring in mixed-species stands. At both sites, I measured height and diameter of all Pinus palustris and cored individuals greater than 10 cm in diameter at breast height. A total of 71 trees were cored; the cores were crossdated and measured and crossdating was verified with the COFECHA program. A strong competition signal within the tree ring records at both sites signified the importance of stand dynamics on Pinus palustris in second-growth loblolly pine stands. These results are probably due to the mix of species within these stands and competition from loblolly pine as both the dominant understory and overstory species. Using Black and Abrams (2003) boundary line method, we calculated release and suppression events from the tree-ring record over the last century and found a very dynamic system. During the 1950s and 1960s, Seacock Swamp experienced major and moderate releases (23% moderate release and 18% major release in the 1950s and 33% moderate release and 49% major release in the 1960s) in response to a diameter-limit cut in 1953. Other major and moderate releases varied at both sites and may be attributed to different forest management practices that were in place throughout the last century however locating historical land use records to validate this was not possible at the present.