Dissertation Research: The Genetic Consequences of Self- thinning in Stands of Loblolly Pine

火炬松(火炬松)在北卡罗来纳州山前的早期演替森林中占据主导地位。资源的稀缺，特别是光线的匮乏，会导致松林变得稀疏：随着树木变得越来越大，对光线的竞争加剧，矮小、遮荫的个体遭受高死亡率。几位研究人员发现，在一些森林树种中，年轻林分的遗传杂合度较低，而较老林分的遗传杂合度较高。这一趋势很可能是在林分间伐时淘汰更纯合的个体的结果。有人建议进行研究，以确定那些杂合度高的个体是否不太可能死亡，以及林分中幸存者的平均杂合度是否反映了由初始林分密度决定的对资源的竞争强度。本研究旨在探讨影响林分遗传结构的自然过程。与松树人工林不同，天然林通过疏伐密林，可能会保持较高的遗传多样性，这可能是杂合子个体的一个好处。天然林间伐的遗传效应可对旨在最大限度地提高树木活力和森林生产力的森林管理工作产生重要影响。

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.