Simulating the effects of site index variation within loblolly pine plantations using an individual tree growth and yield modelThis article is part of a larger document. View the larger document here.
Site index is the most common metric of site productivity in loblolly pine plantations. Generally applied as a constant for a particular stand, it provides an overall measure of a site’s ability to grow trees. It is well known, however, that even the most uniform stands can have considerable variation in site index due to soil factors that influence microsite, variation in genetics from tree to tree, or the uneven application of silvicultural treatments. To better account for such variability, input options to the PTAEDA (version 4.1), an individual tree growth and yield model, were expanded to allow groups of trees at time of planting to be assigned to different site index classes and the variability within those classes to be specified by the user in different ways. This capability allows comparison of alternative methods of introducing site variability into individual tree simulators such as PTAEDA. Preliminary results suggest that the individual tree distance dependent growth and yield model architecture is a useful platform for defining site productivity patterns within stands and evaluating the impact of those patterns on growth and yield.