Ecological assessment of spatial dynamics of forest ecosystem indicators in megacity conditions

The condition and resilience of urban forest ecosystems are subject to increasing anthropogenic pressure associated with the growth of megacities. This study presents the results of long-term ecological monitoring (2018–2022) conducted on the territory of the Forest Experimental Station (LOD) of the Russian State Agrarian University – Moscow Timiryazev Agricultural Academy, a specially protected natural area in Moscow. Five key plots were established along an 800-meter transect with a 3° elevation gradient, differing in mesorelief position, dominant tree species composition, ground vegetation structure, and intensity of recreational load. Field and laboratory methods were used to assess tree stand condition, projective cover of ground vegetation, fractional composition and ash content of forest litter, soil moisture dynamics in the upper soil horizons, humus content, and indices of species richness and diversity. The Jaccard similarity coefficient, Simpson diversity index, and Menhinick species richness index were calculated for woody vegetation across all plots. The results demonstrate that mesorelief, soil moisture, and recreational pressure collectively determine the spatial distribution of organic matter in the soil and litter, the structure of the tree layer, and the projective cover of ground vegetation. Coniferous-dominated plots on the southwestern slope exhibited the highest humus (4.49%) and litter ash content (4.85%), while the most degraded plot - characterized by high soil compaction and proximity to the trail network - showed the lowest projective cover (10%) and canopy density (0.6). Even a minimal elevation gradient of 3° proved sufficient to generate meaningful differentiation of soil biogeochemical processes. The findings highlight the importance of considering topographic heterogeneity and stand species composition in urban forest management and underscore the need for regular long-term monitoring to prevent ecosystem degradation.