Jaime Call, Leigh Moorhead and Aimee Classen, Ecology and Evolutionary Biology, University of Tennessee, Knoxville, TN
Small herbivorous mammals can affect soil and plant communities by shifting plant communities with selective harvesting of plant biomass and by changing nutrient cycling with waste outputs. Our work takes advantage of a 4-year small mammal manipulation experiment in an old-field ecosystem. Previous work in this system has shown small mammals change functional plant community composition, soil community structure, and belowground functioning. Small mammals shift plant composition from a woody and legume dominated community to one dominated by graminoids. Belowground bacterial and fungal abundance decreased with mammal presence. Additionally, belowground functioning, specifically potential extracellular enzyme activity, decreased with mammal presence. With this in mind, we examined whether these changes in above- and below-ground communities persist after a major disturbance such as fire. We hypothesized (i) burning would reset plant community structure to an early succession community between grazing treatments, (ii) burning would reset enzymatic activities between treatments, (iii) these ‘resets’ would be temporary and legacy effects of small mammals would be evident in both plant and soil communities later in the growing season, and (iv) soil community structure would not be altered by burning.
Observational results thus far show burning has reset the plant community to being comprised of primarily the same few species (Tridens flavus, Rubus argus, and Plantago lanceolata). Potential extracellular enzyme activity has increased significantly after burning but only b-gucosidase, showed an affect of treatment (F = 6.188, p = 0.022) and only NAGase showed a time x treatment affect (F = 5.88, p = 0.021). Taken together, our preliminary results suggest that the plant community has reverted to an early successional phase post-burn event and although we see an effect of time on enzyme activity, activities overall do not differ between treatments, indicating burning reset soil functioning to similar levels.