Sensitivity Analysis on Long-Term Fiber Supply Simulations in Georgia

We used long-term simulation analysis in a spatially explicit forest management model called OPTIONS to investigate the impact of the rotation age, intensive management practices, and harvesting limits on wood production, harvesting opportunities, and long-term resource sustainability. The initial forest inventory is compiled from data sets of the US Forest Service Forest Inventory Analysis Unit, various GIS data, Landsat 5 Thematic Mapper imagery, and simplified assumptions about the spatial distribution of different forest cover types. We determined the parameters of the model from published and unpublished literature and from interviews with experts in the area of forest management in the southeastern United States. The sensitivity analyses reveal the impacts of the individual factors of the rotation age, intensive management practices, and harvesting limits and of the interaction of these factors on the sustainability of the forest resources. The results of the analyses suggest that the current timberland in Georgia can easily sustain the current level of harvesting with the current level of intensive management practices for different choices of the rotation ages. The volume available for harvesting would increase with an increasing rate of transition to intensively managed plantations (IMPs) regardless of the level of harvesting limits and rotation age. To ensure sustainability of forest resources under an increasing harvest scenario, part of new plantations would be required to convert to intensive management. The higher the harvesting limit, the more intensively managed plantations needed. The patterns of the changes in the volume available for harvesting by species groups were different for cases of keeping current harvesting limits and IMP levels versus applying increasing harvesting limits and an increasing transition rate to IMPs. Harvestable volumes are significantly different among each level of the three analyzed factors: transition rate to IMPs, rotation age, and harvesting limits. The study informs land use and policy decisionmakers about potential sensitivities of Georgia forest resource productivities to changes in forest practices-related rules and regulations.