A climate model with time varying parameters was fit to longleaf pine (Pinus palustris) tree rings collected from the proposed Harrison Research Natural Area of the De Soto National Forest in southern Mississippi. The purpose of the analysis was to determine if any unexpected disturbances had influenced the growth of the trees. Current September temperature, August rainfall and February Palmer Drought Severity Index (PDSI) were found jointly to be the best variables in the model to predict growth. August rain had a constant significant effect on growth and February PDSI was not significant except between the years 1968-1983. It was concluded that the Harrison area has been in equilibrium for the past 50 years since no apparent outside influences have caused the trees to become less sensitive to climate. Thus, the forest is a good candidate for a Research Natural Area.