アカマツ林土壌における糸状菌の分布に関する研究(第7報) : 鉱質土層の糸状菌集団の性質

The characteristics of the composition of the fungus population in pine forest soil and some factors affecting the fungus population of mineral soil such as relief, soil types and macro-fungus ( Tricholoma matsutake) were investigated by dilution plate method.
The composition of the fungus population was discussed with frequency of isolation of each member in relation to the patterns of vertical distribution. Data were obtained on 94 samples for organic horizons and on 67 samples for mineral soil horizons. Results shown in Table 1 and Fig. 1 indicated that the micro-fungus population of mineral soil was composed of fungi which belonged to TYPE II and TYPE III of vertical distribution patterns, whereas that of organic horizon was composed of TYPE I and TYPE II. Then, the fungus population of the mineral soil could be analysed with quantitative relationship of these two types.
The survey of horizontal distribution of micro-fungi in a stand indicated that although the distribution of fungi was heterogeneous among positions sampled, there existed apparent differences in fungus populations between the upper and the lower part of the slope. Fungal counts of TYPE III were greater in the upper than in the lower part of the slope (Table 3, Fig. 3 and 4).
The drfferences of the micro-fungus populations in soil types were also shown on the examination of black soil and brown forest soil (Table 5 and 6). TYPE II was more dominant in black soil, whereas TYPE III is in brown forest soil (Fig. 5).
Moisture conditions of the soils could be an important factor contributing the observed phenomena.
The fairy ring of Tricholoma matsutake markedly affected on the fungus populations (Table 7 and 8). Almost all fungi were restricted in fungal zone and inside of it where soil was drier than normal soil. The rhizosphere of pine roots in fungal zone were poor in microfungus population, whereas rhizosphere effect was apparently observed in normal soil.