Forest Diversity of the Malaya Laba River Basin in Сonditions of Intensive Influence Wild Animals in the Northwestern Caucasus

Abstract

The article presents the species and structural diversity of coniferous-broadleaved and broadleaved forests of the Malaya Laba River valley and its tributaries under conditions of intensive grazing of wild animals, mainly bison (Bonasus bonasus montanus Rautian, Kalabashkin, Nemtsev, 2000). Most of the described forest types according to the ecological-cenotic classification belong to the nitrophilous-tallgrass group. In the altitudinal profile of the study area, 8 forest types were identified and described: willow-birch tall-herbreed-grass sparse forests, rhododendron-reed-grass pine forests with birch, beech nemoral herb forests, polydominant broadleaf nitrophilous tall herb forests, hornbeam nitrophilous tall herb forests, black alder nitrophilous tall herb forests, maple-ash nitrophilous tall herb forests and willow-gray-alder nitrophilous tall herb forests. In the study area, as a result of nibbling and trampling by wild animals, the undergrowth of dark coniferous species (Abies nordmanniana, Picea orientalis) is heavily damaged, which hinders the restoration of dark coniferous forest types. The undergrowth and generative individuals Ulmus glabra, large ferns (Athyrium filix-femina, Dryopteris carthusiana and Dryopteris filix-mas) are strongly suppressed. In the described areas, 217 species of vascular plants and 72 species of mosses and liverworts were identified. The highest index of species saturation was noted for polydominant broadleaved nitrophilous tall herb forests. The ecological-cenotic core of the flora of coniferous-broadleaved and broadleaved forests of the Malaya Laba River valley is represented by nemoral, meadow-forest-edge and boreal plant species. The greatest number of ecological-cenotic groups was noted for the polydominant broadleaved nitrophiloustall-grass forest type (9 groups), the least for birch-pine rhododendron-reed grass forests (5 groups). In the determined forest types, 10 species of earthworms of the family Lumbricidae were identified, belonging to four morpho-ecological and three chorological groups. Epigeic and endogeic species were found everywhere. Anecic worms lived only in well-drained soils, epi-endogeic ones are largely confined to forest types with easily decomposable litter. The highest diversity rates of lumbricofauna are noted in broad-leaved forests of the nitrophilous tall herb group with the presence of fallen deciduous trees and formed in conditions of intensive grazing of wild animals, which largely supports the populations of epigeic and epi-endogeic earthworm species.