Interior of saxicolous lichens on different types of rocks as a habitat for microfungal communities in Upper Galilee, Israel

Abstract

We examined the diversity and composition of fungi from the interior of saxicolous (rock inhabiting) lichens covering basaltic and chalk rocks at the Alma–Har-Ben-Zimra area of Upper Galilee, Israel. We also compared the composition of lichen-associated and soil microfungal communities inhabiting the two contrasting soil types in the area to trace possible sources of formation of endolichenic fungal assemblages. In the course of the study, 39 fungal species were isolated from the interior of 13 lichen species. Species richness of the endolichenic fungal communities was associated, to some extent, with the growth form of lichens, being higher in those lichens with thick, warted, and wrinkled thalli. Species composition of the communities was characterized by the dominance of melanin-containing microfungi with large, multicellular, and thick-walled spores that significantly increased in abundance in the summer. Dominant species were also known as endophytes and phylloplane-inhabiting fungi; at the same time, typical soil-borne species were extremely rare components of the isolated endolichenic communities. Some endolichenic melanized microfungi were comprised by coprophilous species prevailing in some lichen thalli; this observation was probably due to a long period of use of the studied area for cattle grazing. Protective morphological features are important for fungi inhabiting the interior of lichen thalli characterized by limited nutrient sources, low-water availability, and restricted aeration. In addition, endolichenic fungi should resist the activity of various extracellular secondary metabolites produced by their host lichen species.