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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.

Germination and growth of 12 native herbs, shrubs, and trees were followed in five litter components characteristic of successional stages of the northeastern Minnesota forest. Various litter components stimulated or inhibited seed germination and seedling growth of some species. Germination and growth were not always similarly affected, suggesting that different factors may be involved. Inhibition and lack of inhibition of some species on certain litter components correlate with natural habitat preferences of these species and the nature of the litter in these habitats. This information can be of use in improving results of seeding for site reclamation and reforestation.

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