Effects of Prescribed Fire on Soil Biogeochemistry in a Mixed Grass Prairie
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Limited information exists regarding the effects of prescribed fire on soil biogeochemistry in the mixed grasslands of North America. This study investigated the effects of prescribed grassland fire on soil biogeochemistry over two growing seasons in the mixed grass prairies of Southern Saskatchewan. Spring burning was conducted in continuously grazed native and tame pastures. Soils were sampled (0-10 cm) 2, 3, 4 and 15, 16, 17 months after fire in burned and adjacent control plots. Investigation of soil biogeochemical changes include the analysis of soil total carbon (C), nitrogen (N), microbial biomass C (MBC), microbial biomass N (MBN), C stock, pH, electrical conductivity (EC) and characterization of the microbial community through phospholipid fatty acid biomarker extraction. Results indicate that the mixed grasslands in southern Saskatchewan are largely resistant and resilient to the effects of disturbance by fire. Slight changes in the microbial community structure were observed in both pastures; burning increased the homogeneity in microbial community composition. Attributed to a post fire nutrient flush, the tame forage pasture had an increase in soil fungi 2-4 months following fire and an increase in the ratio of Gram-negative bacteria to Gram-positive bacteria throughout the duration of the study. Temporal effects on soil biogeochemistry were stronger than fire effects. Pastures responded differently over time, likely due to differences in vegetation composition and abundance as well as land use history. This research shows that the use of prescribed fire is compatible with soil conservation principles, as negative effects on soil biogeochemistry were not observed. Reducing barriers to the use of prescribed fire in grassland management is important for the preservation and productivity of remnant grassland parcels, and the ecosystem services grasslands provide.
DegreeMaster of Science (M.Sc.)
SupervisorLamb, Eric; Arcand, Melissa
CommitteeCongreves, Kate; Stewart, Katherine; Kim Schneider Cheers, Eric, Kim
prescribed fire, soil carbon, soil microorganisms, mixed grass prairie,