ABSTRACT The aim of our work was to establish the dependence of species composition, features of ecosystem distribution in the space and wood-destroying activity of xylotrophs on the functional type of forest, and the cause and degree of its violation. Changes in species composition, spatial distribution and wood-destroying activity of xylotrophic fungi, and disruption of “woody plant xylomycobiont”, “substrate category – xylomycobiont,” were revealed. Changes in xylotrophic diversity in stands were evaluated by diversity indices. Forest and taxonomic characteristics of stands, the reasons and the degree of degradation of forest ecosystems were taken into account. The ability of 37 species of xylotrophs to be indicators of deciduous and coniferous forests in green areas of cities due to recreation, construction and quarrying of granite has been substantiated. The principles of application of the mycoindicators system for improvement, a technique of estimation of character and degree of forest ecosystem anthropogenic transformation, are defined.