Dynamics of the ground vegetation cover during successional recovery of wood sorrel spruce forest on fallow land in the Lisinsky Nature Reserve (Leningrad Region)

The study examines the dynamics of ground-cover vegetation parameters in aspen-dominated communities with tree layer ages of 10, 20, 55, and 65 years, formed within the Lisinsky Nature Reserve (Tosno District, Leningrad Region). The investigated plant communities, located within a single forest tract, were considered as a spatial-temporal series representing the secondary succession of Oxalis-type spruce forests on abandoned agricultural land. Ground-cover vegetation was surveyed with sample plots of 0,1 m², where were recorded total projective cover of the herb-shrub and moss-lichen layers, species-specific vascular plants projective cover, total species richness, projective litter cover, and maximum herb layer height. For these parameters, basic statistical characteristics were calculated. Based on the species composition and cover values of vascular plants, Pielou’s evenness index and Simpson’s diversity index were used to assess dominance and distribution evenness within the herb-shrub layer. The results show that, with increasing age of the tree layer, species richness, total projective cover, herb layer height, and litter cover tend to decline. Diversity indices indicate the absence of dominant species and a high degree of spatial heterogeneity in the herb-shrub layer. Floristic similarity with meadow community in both species composition and species participation remains noticeable for up to 20 years after initial colonization of abandoned land by aspen.