Kaszab Zoltán (szerk.): A Magyar Természettudományi Múzeum évkönyve 65. (Budapest 1973)

Bohus, G.: Soil acidity and the occurrence of fungi in deciduous forests

Table 7. Regulation by mycelium in the solution series Goprinus piraceus Final pH of culture solution Initial pH of unbuffered 30 ml solution pH value after incubation for 1 hour 3.2 4.6 4.0 5.8 6.2 5.2 6.0 6.0 6.0 7.1 6.2 7.9 6.8 Results 1. The fruitbodies and mycelia of terricolous macro-fungi alter after a short time the acidity of unbuffered solutions in nearly every case. A shift in pH fails to occur only when the grade of acidity of the solution agrees with the pH value regulated by the species in question. Some examples of complete series (pH 3 -8), studied in our investigations, are given in Table 8. The fungi effect in general a change in pH from some tenths of degree to 2.5 (Tables 8-16). It can be established on the basis of data obtained that, as will be seen also below, for a part of the species (about 30% of the investigated fungi) the grade of acidity of the soil at their growing site and the pH value to which they regulate are in good concordance. 2. The "acidophilous" species, growing almost exclusively in strongly acidophilous (below 5 pH) forests, can be subdivided into two groups as to pH regulation. The species relegable to the group "acidophilous species I" regulate 4 and 5 pH solutions, not rarely even those with pH 6, to between the pH values 4-5 (Table 9, 10). The acidity value set by the second group, the "acidophilous species II", falls between pH values 5-6 (Table li). The circumstance that in the case of „acidophilous species I" occurrence and regulation falls in the same pH interval implies that of the possible factors the soil pH is an operationally significant factor for them, further that the values between the interval 4-5 pH are not only tolerated but preferred by the same species. 3. On the basis of mycocoenological investigations, conducted until 1965, a first attempt to formulate the Jl value scale was published. The grades of the M value scale, modified surveys made since that time, the measuring of soil pH at the growing sites of fruitbodies, as well as the study of regulation by the fruitbodies, are as follows (with ELLENBERG'S and WALTER'S characterizations, respectively, for the flowering plants in brackets) : R±: (Species occurring exclusively on highly acidic soils). This characterization holds verbatim also for fungi. The number of species assignable to this grade is significant. There are two subgroups: 1. "Acidophilous species I" occur in the pH interval 3.5-5.0, with the fruitbodies regulating pH under 5.0 (5.1) (Table 9); the character species of strongly acidophilous deciduous forests are relegable to mainly this subgroup. 2. "Acidophilous species II" occur in the pH interval 4.0-5.0, with the fruitbodies regulating pH over 5.0 (Table 11). R%: (Species occuring on acidic soils, occasionally advancing also to neutral substrates). In fungi, the members of this grade fructify both on strongly and on