On agar plates more colonies and species of fungi developed from oak leaves from calcareous mull (loose mixed litter and mineral matter) than from those from mor (usually compact litter layer abruptly distinct from underlying soil; without free calcium). Fungal plate counts, mycelial growth and concentration from soil under calcareous mull were lower and plate counts of bacteria and actinomycetes higher than those from mor; those from acid mull were usually intermediate. The characteristics of the fungal flora seemed influenced by water and calcium content through the chemical composition of the vegetation and its litter, and secondly by the physical factors of soil, the saprophagous soil fauna and the non-fungal microflora. The numbers of micro-organisms and mycelial growth in the mineral soil were influenced by temperature, moisture and added fresh litter. Maximum mycelium concentrations in oak soils were in autumn or winter, but not in pine soils.Mycelium was decomposed almost equally fast in mull and mor. The mull had 4-10 times as much chitin-decomposing and mycolytic micro-organisms than mor; mor had more mycophagous oribatid mites, consuming individually 3 times as much in summer than in winter. Fruiting bodies of toadstools were most frequent (partly dependent on soil moisture content) about 2.5 months before mycelium reached maximum concentration. The toadstools were mostly humus and litter fungi in mull, and mycorrhizal fungi in acid mull and mor. Litter fungi occurred in all types.
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