Loblolly pine (Pinus taeda) dominates the early successional forests of the North Carolina Piedmont. Scarcity of resources, especially light, causes the stands of pine to undergo thinning: as the trees grow larger, competition for light escalates and the shorter, shaded individuals suffer high mortality. Several investigators have found that in some forest tree species, genetic heterozygosity is low in young stands and high in older stands. This trend is the likely result of the culling of the more homozygous individuals when the stands undergo thinning. Research is proposed to determine whether those individuals with high heterozygosity are less likely to die, and whether the average heterozygosity of the survivors in a stand reflects the intensity of competition for resources as determined by initial stand density. This research proposes to explore the natural processes which influence genetic structure in forest stands. Natural forest stands, as opposed to pine plantations, may maintain higher genetic diversity as a likely benefit of heterozygous individuals through thinning of dense stands. The genetic effects of natural stand thinning could have important implications for forest management efforts aimed at maximizing tree vigor and forest productivity.
