Effects of Prescribed Burning on Soil Microorganisms in a Minnesota Jack Pine Forest

Abstract

Soil dilution plate counts on selective media for bacteria, streptomycetes, and fungi were made at intervals before and after two prescribed burns on 10—acre jack pine tracts. Carbon dioxide determinations were also made. These tracts were compared with similar tracts cut and unburned and uncut and unburned. Three—year results are given. The number and activity of most microorganisms decreased immediately after fire but rose abruptly to a very high level after the first rainfall following burning. This increase is believed caused by the leaching of ash minerals. Depth and extent of the effects were influenced by intensity of fire and moisture conditions. Number and activity of organisms were generally lower in burned soil the second growing season after fire. Some effects were still noticeable the third growing season. Streptomycete populations were greatly increased the third growing season. Rainfall also caused a fluctuation of microbial populations on the unburned tracts.

Wildland fire in ecosystems: effects of fire on soils and water

“…No differences in microbial population sizes were found 133 days after heating soil to 1,110 °F (600 °C) when compared to unheated soil. Similar responses are common in field studies (Ahlgren and Ahlgren 1965, Theodorou and Bowen 1982, Deka and Mishra 1983 Reenen and others 1992, Staddon and others 1998), whereas some controlled soil heating experiments have found longer delays in recolonization (Dunn and others 1979, Diaz-Ravina and others 1996, Acea and Carballas 1999. Differences between field and controlled-environment studies suggest the importance of wind-or animal-transported inoculum for recolonization.…”

Effect of fire on soil C, N and microbial biomass

“…Degradation of soil, which takes place after fire events, is driven by the deterioration of the soil structure [4,16,21], the loss of soil organic matter content [9,12,20,34,40] and the loss of soil mineral nutrients [10,13,14,26]. Soil microbial biomass is also affected through size reduction, impoverishment of speciographic spectra and reduction in catalytic capabilities [1,18,25].…”

Fire Effects on Soils in Lake States Forests: A Compilation of Published Research to Facilitate Long-Term Investigations

“…An early study of soil microorganisms showed that burning reduced microbial numbers and activity up to three growing seasons following fire, however, these effects were minor and were reduced by precipitation events [58]. Litter decomposition increased over the short term (two weeks) following the 1976 wildfire at Seney National Wildlife Refuge [42], whereas no effects were reported following the 1971 Little Sioux Fire in the Boundary Waters Canoe Area [78].…”

“…Our results indicate that several key areas of opportunity exist to expand our current knowledge of fire effects in the Lake States region. Few of the reviewed publications reported fire temperatures [48,50,58,96], and the level of detail provided for fire behavior information varied from qualitative statements that a fire was "severe" or "intense" to plot-specific measurements of fire intensity and forest floor reduction [57] or field-based assessments of fire severity [55]. Detailed measurements of fire temperature, behavior and severity or fuel consumption must be included in future studies to accurately interpret fire effects on soil or other ecosystem components (e.g., [105]).…”

“…Most studies reported soil nutrient stocks rather than nutrient fluxes or estimations of recovery rates for nutrient pools; this latter data would be valuable for understanding impacts on ecosystem processes that contribute to long-term forest productivity. Nutrient flux data would also be complemented by data on microbial community composition to allow evaluation of relationships between soil ecosystem structure and function by forest type; however, only one study presented both types of information [58]. Of the 63 publications reviewed, only one investigated fire effects on soil macrofauna [53].…”