Effects of Prescribed Burn and Sample Storage Conditions on Microbial Community Structure in Missouri Prairie Soils.

Phospholipid fatty acid (PLFA) analysis is an increasingly popular method for assessing microbial community structure in soils. However, the effects of prescribed burns on prairie microbial ecology, and the importance of sample handling on PLFA biomarkers, are not fully understood. In March 2015, soil samples were collected from the 0-5 cm depth layer at three landscape positions from Golden Prairie (Barton Co.) and Stark Prairie (Hickory Co.) in Missouri. Samples were collected immediately prior to a prescribed burn and immediately following the burn, and a suite of soil health analyses were conducted, including PLFA analysis. In addition, the effects of sample processing and handling were evaluated by comparing the PLFA profiles from soil freeze-dried within 24 hours of collection, oven-dried at 105C, air-dried for 7 and 14 days, and stored field moist at room-temperature for 7 and 14 days. Significant differences were found between the PLFA profiles from the two prairies, probably due to differences in soil type, vegetation, and restoration. No significant differences in PLFA profiles were detected between the pre- and post-burn samples for any of the microbial groups or for total PLFA. Oven-drying had the most dramatic effects on PLFA biomarkers, resulting in a 38% reduction in total PLFA and an 82% reduction in fungal biomarkers. Air-dry storage and field-moist storage at room temperature resulted in similar reductions (~10 – 15 %) in total PLFA. Field-moist storage, however, demonstrated a greater decline in fungal biomarkers than air-dry storage conditions. This study highlights the influence of site characteristics on microbial community structure and emphasizes the importance of proper handling of soil samples for PLFA analysis.