Evaluating Forest Vegetation Simulator Predictions for Southern Appalachian Upland Hardwoods with a Modified Mortality Model.

Radtke, Philip J.; Herring, Nathan D.; Loftis, David L.; Keyser, Chad E.

Prediction accuracy for projected basal area and trees per acre was assessed for the growth and yield model of the Forest Vegetation Simulator Southern Variant (FVS-Sn). Data for comparison with FVS-Sn predictions were compiled from a collection of n = 1,780 permanent inventory plots from mixed-species upland FJJ hardwood forests in the Southern Appalachian Mountains. Over a 5-year projection interval, baseline FVS-Sn predictions fell within 15% of observed values in over 88% of the test plots. Several modifications to FVS-Sn were pursued, including a refitting of the background mortality equation by logistic regression. E J Following the modifications, FVS-Sn accuracy statistics increased to 91 and 94% for basal area and trees per acre, respectively. In plots with high initial stand densities, notable gains in accuracy were achieved by relaxing thresholds that activated a density-dependent mortality algorithm in FVS-Sn. Detailed accuracy results for forest types of the region were generated. Twenty-five-year projection results show size-density trajectories consistent with the concept of maximum stand density index.

SOUTHERN Appalachian Region; FOREST plants; HARDWOODS; BASAL area (Forestry); ACQUISITION of data; MORTALITY; LOGISTIC regression analysis

Southern Journal of Applied Forestry, 2012, Vol 36, Issue 2, p61

0148-4419

Academic Journal

10.5849/sjaf.10-017