Comparative study of structural and ecophysiological features of lichens of different ecological groups in rocky forest communities of northernmost boreal zone (Karelia, Russia)

The anatomical (thickness of layers of fungal and algal symbionts) and ecophysiological parameters (the content of photosynthetic pigments) of two lichen species (Hypogymnia physodes and Umbilicaria hyperborea) from rocky forest communities of northernmost boreal zone (North-West of Russia) were studied. H. physodes is a lichen with foliose thallus morphology and circumpolar distribution which colonizes almost every substrate. U. hyperborea is strictly epilithic lichen with umbilicate type of thallus morphology and arcto-alpine distribution. Despite the fact that the photobiont in two species are closely related taxa (unicellular green algae of the genus Trebouxia) a high variability of photosynthetic pigments content in H. physodes thalli has been revealed, whereas in U. hyperborea, the mycobiotic showed high structural variability. It can be concluded that both mycobiont and photobiont contribute to their adaptation to environmental factors. In the present study it was obtained that the proportion of variation in anatomical structures and the content of photosynthetic pigments probably less depends on taxonomic position of photobiont and more determined by the plasticity of the individual components of the symbiotrophic organism