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Abstract
Loblolly pine (Pinus taeda L.) plantations are extensive in the southeastern United States and represent a significant component of the forest products market in this region. For optimal stand-level management decisions, the growth response to any combination of mid-rotation silvicultural treatments like fertilization, thinning, or competing vegetation management needs to be accurately predicted over the long-term. This dissertation presents a review of the most common mid-rotation silviculture treatments applied in loblolly pine plantations and provides a conceptual framework about their effect on growth. The Growth and Yield system presented here consists of a novel taper equation based on a penalized spline regression, a compatible dynamic growth system of differential equations for dominant height, basal area, and stand density, which includes a growth modifier to account for mid-rotation silvicultural effects, and a novel method to recover the diameter distribution for projected stand after mid-rotation silvicultural treatments. The Growth and Yield system and the recovery diameter model were fitted with the regional Thinning and Mid-Rotation Treatment (MRT) study established by the Plantation Management Research Cooperative (PRMC) at the University of Georgia, which includes various site qualities and growth conditions in thinned and non thinned stands. Therefore, the proposed model well represents regional growth conditions. Additionally, the models presented are new approaches for the southern loblolly pine plantation modeling and were shown to be improvements over existing practices.