The structure of longleaf pine (Pinus palustris Mill.) forests of the southeastern United States coastal plains has been the focus of numerous studies. By comparison, the longleaf pine forests in the mountains of Alabama and Georgia are not well-understood. Much of what little work conducted in these areas occurred prior to the mid 20th-century. It is estimated that less than 0.004% of the remaining longleaf pine stands are considered to be old-growth, trees greater than 100-120 years old. Of this total, less than 1% of the old-growth stands are found in the montane portion of longleaf pine's range. Several of these old-growth longleaf pine stands occur on the Mountain Longleaf National Wildlife Refuge located in northeastern Alabama, USA. A 1998 study documented the conditions in two old-growth longleaf pine stands on the Refuge. The purpose of that study was to describe the age and stand structure and to shed light on the past disturbance and replacement patterns of two remnant old-growth longleaf pine stands. 

Results/Conclusions

In 2006, these two stands were re-measured to document what changes had occurred in the following years. One stand was subjected to a relatively intense prescribed fire in the interim while the second stand was not. Both stands suffered a decline in tree density, but only the stand which had been burned experienced a loss in basal area. This finding was a surprise given that fire is needed to maintain longleaf pine ecosystems. Spatial statistics were used to determine if the mortality was related to the prescribed fire and to the location of trees to each other. A cluster analysis using the Ripley’s k-function was conducted to determine if there were significant clusters at different distances within the stand. The next step was to evaluate potential causes of the clustering by analyzing tree to tree distances. Due to the steepness of the terrain, slope and aspect were also evaluated as potential driving forces for the mortality.