ESTIMATING TREE GRADES FOR SOUTHERN APPALACHIAN NATURAL FOREST STANDS

Log prices can vary significantly by grade: grade 1 logs are often sev eral times the price per unit of grade 3 logs. Because tree grading ru les derive from log grading rules, a model that predicts tree grades b ased on tree and stand-level variables might be useful for predicting stand values. The model could then assist in the modeling of timber su pply and in economic optimization. Grade models are estimated for ten species groups found in the southern Appalachians, using data from sev eral thousand trees and permanent plots in the USDA Forest Service's F orest Inventory and Analysis (FIA) database. The models correctly pred icted grades of a majority of trees in both a test and a validation da ta set, and predictions of grade proportions across a sample of the po pulation were usually within three percentage points of actual grade p roportions. But success of models varied across species and diameter g roups. Considering several measures of modeling success, the most accu rate models were those predicting tree grades for softwoods and larger hardwoods.