Comparison Of Plot- And Stand-Level Projections Of Simulated Loblolly Pine (Pinus Taeda) Stands

Estimating current stand conditions and value is often required for making management decisions. However, costs and logistical constraints make yearly inventory impractical in most settings, necessitating the use of growth and yield models. Projection of plots aggregated within stands, denoted as stand-level projection, and aggregation of individual projected plots within stands, denoted as plot-level projection, are two strategies used to predict stand parameters at future times. This study investigated the differences in the two projection strategies under differing levels of spatial heterogeneity and stand development. Simulated mapped stands and samples, along with three whole-stand models, were utilized to perform the comparisons. The results indicated that the two methods produced similar projections in terms of dominant height, basal area, and stems per hectare under most situations. As spatial heterogeneity increased, the stand-level projection indicated a significant bias of predicted total volume compared with the plot-level projection regardless of plot size as indicated by Jensen's inequality. The model used made a noticeable impact on the differences, while thinning did not alter the patterns of observed differences. When implementing projections at the whole-stand level, careful consideration of stand heterogeneity and the growth and yield model is recommended.