Abstract:
The Normalized Burn Ratio and Composite Burn Index were used to classify burn severity in three sites that experienced lightning-ignited wildfire in the year 2000. The effect of burn severity (unburned, low, moderate, and high severity classes) was
investigated on vegetation and soil microbial community composition. Vegetation
communities showed a strong response to burn severity, with distinct communities associated with each burn severity class. Indicator Species Analysis was used to
identify plant species associated with each burn severity class; one interesting result
from ISA was that trembling aspen (Populus tremuloides) seedlings emerged as an
indicator of the moderate severity class. Species richness and tree seedling density
differed among burn severity classes. Soil microbial communities were analyzed using Phospholipid Fatty Acid analysis and showed moderate variation among burn severity classes and study sites. Total soil carbon and nitrogen did not differ with burn
severity. The C:N ratio, total soil S, and soil pH differed significantly among burn
severity classes. While the effect of burn severity is pronounced upon vegetation three
years post-fire, effects on soil microbial communities are less evident. This could be
attributed to the insulating properties of soils, the time elapsed after fire, or it could be an artifact of the sampling technique.
