The distribution of micro-fungi in organic horizon of pine (Pinus densiflora) forests was examined by soil dilution plate method.
Samples were collected from nine localities (TABLE 1). Organic horizon was divided into L, Fand H layers.
Numbers of fungus colonies are shown in TABLE 2. Total numbers of fungi are fewer in fresh litter layer than in more decomposed layers.
Frequency of isolation and maximum number of each fungus are shown in TABLE 3. In general, the greater the frequency of isolation is, the greater the maximum number of any one fungus is. The most dominant fungi occur constantly in each layer but less dominant ones occur more frequently in some layer. Its tendency accords with the patterns of vertical distribution of micro-fungi.
The dominant fungi in A_0 horizon are shown in TABLE 4. Except in several cases, the fungi such as Penicillium, Trichoderma, Mucor ramannianus, Cephalosporium sp. Wl which are most frequently isolated from soil by dilution plate method are dominant. In this respect the fungus flora of the forest soil seems to be cosmopolitan.
The patterns of vertical distribution of micro-fungi in A_0 horizon of pine forest are summarized in TABLE 5. The fungi which belong to TYPE I are subdivided into two groups, i. e. TYPE L and TYPE L-F, the former is more dominant in upper part of L layer, and its vertical distribution is restricted, the latter is dominant in lower part of L layer and its distribution is wider than the former. The fungi which belong to TYPE II are subdivided into three groups, i. e. TYPE F, TYPE F-H, and TYPE H. The fungi of TYPE F and TYPE H are characteristically most dominant in each layer but ones of TYPE F-H distribute more widely.
These patterns of vertical distribution in A_0 horizon seem to indicate some aspects of fungus succession in the decomposition of litter.