Forestry Growth and Yield Models

The southern Appalachian forest contains pure pine stands, pure hardwood stands and mixed pine-hardwood stands. Until quite recently, most growth and yield models applicable to the southern Appalachian mountains were stand level models that could be used on one, and only one, type of forest stand. A good overview of growth and yield models for oak forests can be found in Chapter 10 of Johnson et al. (2002).

Growth and yield research in the South has been primarily focused on pine plantations and, to a lesser extent, on natural pine stands. The models developed from this research were fit with data from the piedmont and coastal plain regions throughout the South and tended to be useful for very specific conditions, i.e. old field loblolly pine plantations in the coastal plain of Georgia. The predominant use of data from the piedmont and coastal plain is quite understandable because only 10% of southern Appalachian forests are pure pine stands. Consequently, the accuracy of the existing group of pine models is suspect when applied to pine stands growing in the southern Appalachian region.

A number of hardwood growth and yield models have been developed for the southern Appalachian region and these have been tested for accuracy (Rauscher et al. 2000).

A new variant of the Forest Vegetation Simulator (FVS) was developed and deployed by the USDA Forest Service in 2001. This southern variant of FVS is an individual tree simulation model and can thus be used for all forest types in the southern Appalachian region. The availability of this new model is considered a major breakthrough. It is currently being tested for accuracy.