On the analysis of cenopopulations of the epilithic lichen Rhizocarpon geographicum on the territory of the Northwestern White Sea

We studied cenopopulations of the epilithic lichen Rhizocarpon geographicum on boulder formations (pits, heaps) - archaeological sites, which are located in forest communities of the northern taiga zone in the north of the Republic of Karelia and in the south of the Murmansk region. Two approaches to the allocation of an intrapopulation unit for lichens were used in the work: a separate individual (thallus) and a monoid spot were considered as a functional unit when small thalli merge or when their fragments grow, as within a spot it is impossible to unambiguously identify the boundaries of individual thalli. Synusiae involving Rh.geographicum were analyzed in the field, they were photographed relative to the measuring standard. 127 photos were obtained, in which the areas of thalli and rhizocarpon spots were determined in triplicate using ImageJ program. For each object, the average values of the area of Rh. geographicum thalli or monospecific spots were calculated, and variation series were constructed. Analysis of the distribution of individual thalli and monoid spots in the coenopopulations of the two study sites revealed similar features. Distributions in variation series are described by a logarithmic function (R2...0.78-0.95). In coenopopulations, individual thalli were detected almost three times less than monoid spots. General patterns were identified. Monospecific spots may be smaller in size than individual thalli. Small thalli in the sinusia do not reach the sizes described by the logarithmic function as a result of competitive relationships. Large spots significantly exceed the values of the equations. It was revealed that monoid spots of Rh. geographicum formed at early stages behaved like individuals, which allows considering them as a functional unit of the coenopopulation along with discrete thalli. Monoid spots change structurally over time, and can form from thalli and smaller spots at different periods of their development. The largest spot is not the oldest in the coenopopulation, which makes it impossible to use this approach in lichenometry.