Initial effects of prescribed fire on quality of soil solution and streamwater in the southern Appalachian mountains

Prescribed burning is being used in the Conasauga River Watershed in southeastern Tennessee and northern Georgia by National Forest managers to restore degraded pine/oak communities. The purpose of these burns is to restore shortleaf pine (Pinus echinata Miller)/mixed-oak forests with more diverse understories, which include native bluestem grasses (Andropogon gyrans Ashe and Schizachyrium scoparium (Michx.) Nash). Although burning might be an effective tool for restoring these stands to a shortleaf pine/mixed-oak/bluestem grass community type, it is not known whether these restoration burns will have a negative impact on water quality. Six subwatersheds (similar in vegetation, soil type, stream size and location, and disturbance history) were located within the Conasauga River Watershed. Four of the sites were burned in Mar. 2001, and two sites were designated as controls. To evaluate initial effects of prescribed burning on water quality, we measured soil solution and streamwater nutrient concentrations and streamwater sediment concentration (TSS; total suspended solids) weekly over a 10-month period. Consistent with goals of the land managers, all the prescribed fires resulted in low- to moderate-intensity and low-severity fires. Soil solution and streamwater NO(3)(-)-N and NH(4)(+)-N did not increase after burning on any of the sites. We found no differences in TSS between burn and control streams in any of the sample periods. In addition, we found no detectable differences between control and burned sites for concentrations of PO(4)(3-), SO(4)(2-), Ca(2+), Mg(2+), K(+), or pH in soil solution or streamwater. Thus, these prescribed restoration fires did not have a significant effect on soil solution and stream chemistry or stream sediment (TSS) concentrations. Our results suggest that low-intensity, low-severity fires, such as those in this study, could be used as a tool to restore vegetation structure and composition in these mixed pine-hardwood ecosystems without negatively impacting water quality.