Kaszab Zoltán (szerk.): A Magyar Természettudományi Múzeum évkönyve 68. (Budapest 1976)
P. Verseghy, K.: Quantitative investigation of xerothermophilous lichens of sandy soil
the phytomass is quite evident within a single growing season, however the seasonal changes of the phytomass of the slow-growing dwarf lichens are all the more difficult to explain. On the basis of path-analysis summer and winter are clearly distinct in their effect in both associations. In winter and during autumn and early spring productivity is positive. The sequence of importance of the primary active factors in the case of Festucetum vaginatae is global radiation, humidity, precipitation and radiation minimum. In contradistinction the "other" factors not examined by us are the most important in the summer period, and this may be in connection with the growth of flowering plants and their effects upon lichens. Precipitation has a positive, while humidity has a negative influence. In the course of three summer investigations, from the total productivity values of twelve months, eight were negative, indicating that it is during this period that the deterioration, disintegration process is dominant over the reproductive one in lichens. In the case of the one-year-old, open Brometum the "other" factors are primary •during the winter period, while in summer they come fourth. In winter the lichens have unrestricted dominance over grassland ; the factors primarily affecting their productivity have not been examined by us (the so-called "other" factors) and are, therefore, unknown to us. The radiation minimum ranks first in summer and second in winter as a déterminent ; global radiation is second in summer and third in winter. It is an interesting phenomenon that humidity, considered to be crucial in the case of lichens, comes either fourth or fifth in place throughout the year in these grasslands (Table 1). If we are to rank the climatic factors, the order of their relevance to the two dominant species of lichens (Cladonia magyarica and Cl. furcata) of the two associations is as follows: g/m 2 Fig. 3. Total production of lichens in Brometum tectorum association in g/m 2 .
