To identify and describe the forest communities of the Green Book of the Bryansk region, the habitats of 10 natural monuments have been surveyed. Forest communities are represented by formations of oak forests and ash forests. Thanks to biomonitoring work followed by analysis of syntaxonomic diversity, observation bases have been created for 6 associations and one subassociation. The presence of biocenoses of the rare subassociation Mercurialo perennis - Quercetum roboris carpinetosum betuli Bulokhov et Solomeshch in Bulokhov et Semenishchenkov 2015 in the nature monument “Lyubin Khutor” of the Novozybkovsky district, and the rare association Ulmo laevis - Fraxinetum excelsioris Bulokhov et Semenishchenkov 2008 for the “Ancient Park in Lyalichi” in Surazhsky district have been cited for the first time. The differentiation of habitats, presence of buffer zone, size of protected area stage of demutation restorative post-anthropogenic successions determines the diversity of the ecological-phytocenotic structure of the studied forest communities. The cenotic and structural characteristics of rare and reference forest communities correspond to the model descriptions in the Green Book. A new subassociation involving Sanicula europaea L. is justified by the method of ecological-floristic classification of J. Braun-Blanquet (1964). This allows to identify the heterogeneity of biotopes and the favorable phytocenotic environment of a regionally rare species. The existence of valuable biotopes of the system EUNIS-ESy system (2020): category T - Forest and other forest lands with four types: T1B, T19, T13, T1E is established as criteria by means of units of ecological-floristic classification of forest biocoenoses. The experience gained during long-term community research of the unique environmental catalog of the Green Book will be used in the preparation and publication of similar lists that will contribute to solving the problems of protection of plant communities in Russia.