Diameter Distribution Models: Loblolly Pine Plantations

A parameter recovery procedure for the Weibull distribution function based on four percentile equations was used to develop a new diameter distribution yield prediction model for unmanaged slash pine (Pinus elliottii Engelm.) plantations in east Texas. This new model was similar in structure to the model of Lee and Coble (2006) in their work with east Texas loblolly pine plantations. The new model was compared to the diameter distribution model of Lenhart (1988), which was developed for slash pine plantations in east Texas, as well as to two other models developed using iterative techniques suggested and inspired by Cao (2004). The model developed in this study was preferred over Lenhart (1988) and the other two models in prediction of total trees per acre, basal area per acre, quadratic mean diameter, and cubic-foot volume per acre (wood and bark, excluding stump). An example cubic-foot volume per acre wood and bark yield curve is provided below (Figure 2) for an initial planting density of 600 trees per acre for a range of site index values. We recommend that the model developed in this study be used to estimate growth and yield of east Texas slash pine plantations.