Kaszab Zoltán (szerk.): A Magyar Természettudományi Múzeum évkönyve 65. (Budapest 1973)
Bohus, G.: Soil acidity and the occurrence of fungi in deciduous forests
ANNALES HISTORICO-NATURALES MUSEI NATIONALIS HUNGARICI Tomus 65. Budapest 1973. Soil Acidity and the Occurrence of Fungi in Deciduous Forests By G. BOHUS, Budapest Abstract — Mycocoenological investigations, the measuring of soil acidity where fruitbodies occur, and the values of pH regulation by fruitbodies revealed that in 30% of the species studied the rate of soil acidity where fruitbodies occur and the pH values to which they regulate are in good concordance. In the case of members of "acidophilous species I.", soil pH is an "operationally significant" factor, and these species not only tolerate but prefer the pH interval 4-5. The It-value scale formed in 1967 is controlled and modified. Concerning flowering plants, there are more of less significant interconnections between the range of certain species and the rate of soil acidity, in climatically and floralhistorically uniform areas. Some species have very strict, others wide amplitudes, occasionally so wide indeed that they are designated as indifferent to the pH value of the soil. The behaviour of numerous plant species is regionally different, the cause frequently lying in the fact that the pH value runs parallel in certain localities with other factors which are important for the existence of the plant. It was also repeatedly contended that the role of soil pH is only apparent, with the leading role being played in essence by competitive forces (KNAPP 1953). Recognized pH values and the statistically established optimum interval considerably widens for most plants, so that only a few definitely ,, säur er stet" or „basenstet" species can today be recorded (ELLENBERG 1958). There exist, however, flowering plants which, in the various parts of the world, prefer invariably the same acidity intervals, e. g. the Ericaceae, etc. For these, soil acidity or the complex of its effects, are habitat factors of probably determining importance. The investigations of terricolous macro-fungi indicate, however, that the soil pH appears to represent one of the "operationally significant" factors, among the possible ones, for a greater quota of fungi than for the flowering plants. Such, at least, seems to be the case. In the course of mycocoenological investigations, conducted in 1951 -1972 in various deciduous forest communities in divers areas (BOHUS & BABOS 1960, 1967), we have obtained numerical data revealing that there exist a great number of species which occur only in deciduous forests (Quercetalia robori — petraeae) with highly acidic (below pH 5) soils, and only rarely in locally acidified sites of forests on soils of a weaker acidity (Table 1, and for comparison Table 2). Investigations concerning the role of pH seemed to call for a continuation for two reasons: 1. Field observations render information, according to ELLENBERG (1958) and other authors, on tolerance against and not on preference for certain pH values; this latter can be established by physiological experiments; 2. The order of precedence of the operative factors can be established, according to JUHÁSZ — NAGY (1959) and others, only by long field experience and an analysis of experimental data; after separating the most probable factor, the connections can be further analysed by more refined methods. Ann. Hist.-nat. Mus. Nat. Hung., 1973, 65
