PARENT SESSION
Poster Session # 11: Disturbance Ecology.

Tuesday, August 5 Presentation from 5:00 PM to 6:30 PM. SITCC Exhibit Hall B.

Spatial patterns of fuel loads, fire intensity, and microbial biomass in a longleaf pine forest.

Kennard, Deborah^*,1, Outcalt, Kenneth², Lockaby, Graeme³, Governo, Robin³, ¹ USDA Forest Service, Southern Research Station, Auburn, AL² USDA Forest Service, Southern Research Station, Athens, GA³ Auburn University, Auburn, AL

ABSTRACT- Characterizing spatial patterns of fire intensity, as well as patterns of soil resources following burning, is a potentially important and rarely considered means of understanding mechanisms of regeneration following fire. Fire intensity can vary at fine spatial scales depending on local differences in fuel loads, moisture, and wind. This spatial variation in fire intensity, i.e., patchiness, is a characteristic feature of most fires, and provides a critical mechanism to alter spatial patterns of regeneration. We characterized spatial patterns of pre-burn fuel loads, fire intensity, post-burn soil microbial biomass, and post-burn fuel accumulation in a longleaf pine forest in the coastal plain of Alabama. These variables were measured at 100 spatially referenced points within a 10 ha plot. Pre- and post-burn fuel loads were estimated using percent cover and height of live and dead fuels, and point intercept counts of down-woody fuel. Maximum temperature during the prescribed burn, which served as an indicator of fire intensity, was measured using heat-indicating paints. Soil microbial biomass was measured on soil sampled 6 weeks following the burn and analyzed using the chloroform fumigation-extraction method. Geostatistical analysis showed that variability of fuel loads, maximum fire temperature, and soil microbial biomass indicators exhibited strong spatially explicit structures; 77-95% of their sample variance was spatially dependent. However, the scale of this spatial dependence differed from 2 m (microbial biomass C), to 13 m (fire intensity), to 33 m (fuel loads). These results suggest that fire behavior can change significantly over relatively small scales and that patterns of fire intensity can only partially predicted by pre-burn fuel loads.

Key words: geostatistics, fire intensity, microbial biomass, long leaf pine