Over the past two centuries atmospheric CO₂ concentrations have been rising exponentially, and have contributed to changing climatic conditions, prompting development of strategic plans to mitigate the rising atmospheric CO₂. Restoring forests has been suggested as a cost-effective mitigation strategy with great potential. Predictive modeling of tree growth and mortality can help select the species with optimal carbon uptake and storage potential for a given area. Evaluation of potential limiting factors of individual tree productivity and mortality can be translated into a numerical model – a practical tool for examining the emergent stand-level carbon uptake and storage patterns under given environmental conditions. The objectives of this study were to (1) evaluate climatic, edaphic, and ontogenetic factors that affected tree growth and mortality in Florida forests, (2) develop an individual-based model which would incorporate the significant climatic, edaphic, and ontogenetic effects on tree growth and mortality; and (3) use the model to evaluate forest carbon uptake and storage potential across tree species and environmental gradients in Florida.
Results/Conclusions
The initial assessment of maximum tree growth potential and mortality, using data available from the U.S. Forest Service National Forest Inventory dataset, revealed differences in specific environmental drivers for growth of slash pine, loblolly pine, and longleaf pine. Preliminary results suggest that site temperature has a positive effect on growth rates of slash, longleaf, and loblolly pine, whereas age has a negative effect. However, the magnitudes of their effects differ across species. Longleaf pine growth rate was found to be most affected by changes in temperature, while slash pine growth rate was least affected. Age had the greatest negative effect on the growth rate of loblolly pine. Slash pine and longleaf pine growth rates were negatively affected by increases in soil moisture content. Of the three species selected only slash pine showed sensitivity to soil C:N ratios, indicating that nitrogen might be a limiting nutrient for this species in Florida. Loblolly pine was the fastest growing species of the three, but also the species with the lowest longevity. These environmental and ontogenetic effects were incorporated into an individual-based model to simulate stand-level patterns of forest biomass carbon uptake and storage.