Fires occur naturally, yet increased drought due to climate change has increased fire frequencies across many regions of North America. Specifically, in the Southern Appalachian Mountains, wildfires with high severity occurred in 2016 due to increased drought. It is important to understand ecosystem responses to this disturbance and to learn how and if our environment is resilient, and capable of recovery. Soils were collected from two sites in the Great Smoky Mountains National Park (GRSM) in Tennessee and the Nantahala National Forest (NNF) in North Carolina, USA. Based on the Composite Burn Index, 8 plots were established within Control, Light, Moderate, and Severe burns and sampled for mineral subsoil (approximately top 15-cm). Soil samples were collected over 3 time points (5 months, 9 months, 1.5 years post fire) after wildfires were no longer smoldering at both sites and among burn severity plots. Soil samples were prepared for potential extracellular enzyme activities of beta-glucosidase (BG), cellobiohydrolase (CBH), beta-xylisodase (BX), beta-acetylglucosaminidase (NAG), leucyl aminopeptidase (LAP), and acid phosphatase (AP) using previously established high-throughput fluorometric assays. Soils were also extracted for microbial gDNA to quantitatively determine both bacterial and fungal population sizes across burn severity, site, and time since fire.
Results/Conclusions
Preliminary analyses (C and P-acquiring enzymes) for NNF indicate that substrate-specific carbon (C) acquiring enzyme production differed with wildfire severity 5 months after the burn event. CBH (p = 0.01) production was greater in Severe NNF plots whereas BG production did not differ among Severe and Control NNF plots (p = 0.47). Likewise, AP (p = 0.31) did not differ among Control and Severe NNF plots 5-months after the burn event. This is in congruence with other work that has demonstrated total C is significantly lower in Severe Burn plots in NNF and GRSM therefore soil microbial C-scavenging is predicted to increase. Additional data will reveal the temporal differences in potential EEA in GRSM and microbial population sizes in both sites across 9-month and 1.5 year time points. Future research goals are to continue examining these areas for five years and also observe the vegetation that recovers. This will help us better understand how Southern Appalachia environments recover after wildfires and provide critical information regarding soil microbial and vegetation recovery.