An alternative model for describing even-aged stand-level sawtimber growth in Pennsylvania

A nonlinear stand-level model was formulated to estimate net and gross sawtimber volume for Pennsylvania forests based on measured plot-level observations from the Pennsylvania Department of Conservation and Natural Resources Bureau of Forestry’s continuous forest inventory database. The resulting model, although derived using specific data from a unique inventory system, provides an application of fitting a dimensionally compatible function to model sawtimber yield while maintaining flexibility to differentiate stand-level growth characteristics such as mean annual increment (MAI) and the age of culmination of MAI among seven forest types, three site classes, two stocking levels, and four ecoregion clusters. Results show later culmination and decreased productivity as site quality and stocking level decrease, varying among forest types and ecoregion clusters. Evaluation of the Akaike information criteria showed the strength of the subsequent model in projecting growth and yield compared to the state’s current yield model from Gilabert et al. (North. J. Appl. For. 27[4]:140–150, 2010).