Application of linked regional scale growth, biogeography, and economic models for southeastern United States pine forests

The southern United States produces over 50% of commercial timber harvests in the US and the demand for southern timber are likely to increase in the future. Global change is altering the physical and chemical environmental which will play a major role in determining future forest stand growth, insect and disease outbreaks, regeneration success, and distribution of species across the region. Therefore, it is necessary to better understand the relationships between soils, forest composition, growth, and economic demand to determine whether forests in the Southern US can satisfy future forest resource demands. Integrated models can be a useful tool to understand future timber supply and demand under changing environmental and social conditions. This paper linked DISTRIB, a forest biogeography model; PnET-II, a lumped parameter forest productivity model; and SRTS, a economic model of southern timber markets to attempt to understand the interactions between forest distribution, productivity and economics. As an example of model linkage, we examined the impact that the Hadley2Sul general circulation model predictions of climate change would have on southern US timber supply, harvest and geographic distribution. The results of the linked models demonstrate the inertia of the forest ecosystems and economics to changing environmental conditions. Despite a 3degreesC increase in mean annual air temperature, regional forest productivity, volume and harvest were not greatly altered. The models did predict shifts in the pine range, and inter-regional changes in forest harvest. Results of the linked models are presented and the need for expanded research on linked dynamic model development to predict future US timber supply and demand are discussed.