The diagnostic role of lichens associated with their indicator properties is reflected at different levels of the syntaxonomical hierarchy of psammophytic grass vegetation. The aims of this article are to characterise the diversity of the lichen groupings of psammophytic grass communities in the Southern Non-Chernozem zone of Russia and to evaluate the indicator and diagnostic capabilities of lichens in the classification of this type of vegetation. The authors used 106 releves for the analysis made within Bryansk, Kaluga, and Smolensk oblasts of Russia (between 52 degrees 00' and 54 degrees 50' N, 30 degrees 60' and 36 degrees 30' E). The climate of the oblasts is temperate continental with moderately cold winters and moderately warm summers. According to the botanico-geographical zoning, the territory of the study area is divided by conditional boundaries of three sub-provinces: ValdaiskOnezhskaya (Eurasian taiga zone), where broad-leaved-spruce forests on soddy-podzolic soils are zonal; Polesskaya (Eastern European broad-leaved forest zone) with zonal broad-leaved forests with spruce on soddy-podzolic and gray forest soils; Central Russian (Eastern European broad-leaved forest zone), where broad-leaved forests without spruce on gray forest soils are zonal. Vegetation classification was implemented using the J. Braun- Blanquet approach. The lichens with a coefficient value above 20 (p < 0.05) and constancy above 20% were assigned to the diagnostic species for the syntaxa. The ecological regimes of habitats of communities were assessed using the scales of H. Ellenberg and E. Landolt based on unweighted average values in the JUICE program. DCA- ordination is implemented using the R package (https:// www.r-project. org) integrated with the JUICE. The correlation of ordination axes with environmental factors was determined using the Kendall correlation coefficient in the PC-ORD 5.0 program. The differences in habitats of the established syntaxa according to the studied environmental factors were assessed by the Krusker-Wallace test. The releves used for the analysis belong to 3 associations within 3 alliances and 2 orders of the class of psammophytic grass vegetation of Europe Koelerio-Corynephoretea canescentis Klika in Klika et Novak 1941; and 5 more releves belong to non-rank 'communities' within the same class representing different stages and ecological and geographical variants of the settlement of psammophytic habitats. The terricolous lichen groupings of the examined psammophytic communities include 36 species and show considerable similarity with that in the pine forests of the region. The richness in lichens in communities from the subtaiga is twice as high as in the sample of releves from the broad-leaved forest zone. In watershed psammophytic communities of the broad-leaved forest zone, this indicator is the lowest, and the noted lichen species are mainly eurytopic and widespread. A trend towards a greater azonal nature of the terricolous lichen groupings of psammophytic communities was revealed in the broad-leaved forest zone, while in the southern subtaiga, the composition of lichens of such phytocoenoses has well- defined boreal features. A small number of lichens show high fidelity to individual syntaxa, determined on the basis of constancy indicators and values of the statistical f-coefficient. Not a single species is characterised by its high value, despite the high rates of constancy of some species in certain coenofloras. Therefore, in our opinion, it is inappropriate to include the listed species in the diagnostic combinations of the corresponding syntaxa. Using the DCA- ordination method, it was demonstrated that the gradients of lichen groupings parameters have the highest correlation at a statistically significant level with the complex gradient of the mineral nitrogen richness of the substrate and light.
