Effects of Long-term Late Winter Prescribed Fire on Forest Stand Dynamics, Small Mammal Populations, and Habitat Demographics in a Tennessee Oak Barrens

Stand structure and composition of pyric oak barrens communities were shaped by natural and anthropogenic fire disturbance regimes. Due to fire suppression and land use changes, oak barrens have become rare. In 1963, a study was implemented to evaluate the restorative effects of annual and five year periodic fire on an “oak barrens” hardwood forest at the University of Tennessee Forest Resources Research and Education Center near Tullahoma, TN. The initial study was a randomized block design and analyzed the effects of short-term prescribed fire on hardwood reproduction, herbaceous vegetation, fuel loading, and soil characteristics. Since inception, additional studies of short-term and long-term effects of continual prescribed fire on various components of the ecosystem have been conducted.

In 2005, a follow-up study was conducted to evaluate the effects of long-term prescribed fire on stand dynamics, wildlife habitat structure, and small mammal populations. Stand structure and development were documented and treatment differences analyzed. The effects of annual prescribed fire on small mammal abundance and habitat characteristics were compared across treatments at 3 intervals, pre-burn, postburn, and end of season using repeated measures mixed models ANOVA. Predicting small mammal abundance using habitat characteristics was performed using multiple linear regression with stepwise selection.

Annual and 5-year periodic burning for 42 years decreased canopy cover and increased vertical and horizontal understory structure. Regeneration mortality was high for both burn treatments and recruitment was unsustainably low. The 5-year periodic treatment was the most structurally diverse and had the highest small mammal abundance and diversity. Three models for small mammal abundance had one temporally-related variable as the most significant: percent cover of vines. Woody height, percent cover of forbs, and percent cover of bunch grasses were also significant variables.

Long-term annual and 5-year periodic prescribed fire does not restore oak barrens to historical accounts of the area and is not sustainable. The amount of overstory oak trees continues to decline with continuous burning. A period of time without burning is required for ingrowth to become established in the overstory and be large enough to withstand burning.