In the study of the lichen-rock interface, light microscopy, scanning electron microscopy (SEM) in secondary emission mode and transmission electron microscopy are the most commonly used techniques. As these methods have some limitations, there is a need to explore other techniques for observation of the lichen-substrate interface. One of the most promising methods is the application of SEM in the back-scattered electron (BSE) emission mode.
The thallus of Aspicilia intermutans (Nyl.) Arn. growing on granitic rock was examined by SEM in BSE mode. The detailed preparation of transverse sections of the lichen-rock contact zone is presented. The BSE scanning images of the lichen-rock interface obtained present new insights into the ultrastructural features of the biological components, providing more information about the biogeophysical and biogeochemical weathering of rock.