Reforestation in post-agrarian areas of Western Transbaikalia
A.P. SIZYKH, V.I. VORONIN, V.A. OSKOLKOV, A.P. GRITSENYUK
Siberian Institute of Plant Physiology and Biochemistry, Siberian Branch, Russian Academy of Sciences, Irkutsk, Russia
Keywords: fallow land, grazing regimes, forest-steppe, steppe communities, forests, Baikal region
Abstract
The tendencies of forest formation on fallow lands of different years, currently acting as rangelands, in post-agrarian areas of Western Transbaikalia have been established. When assessing the nature of the restorative dynamics of forests on fallow lands, the typological and species composition of phytocenoses of the surrounding areas, not previously used for plowing, was taken into account as much as possible. In the forming herbaceous communities on fallow lands and steppe plots, the presence of woody species such as Scots pine (Pinus sylvestris L.), more rarely Siberian larch (Larix sibirica Ledeb.), and sometimes dwarf elm (Ulmus pumila L.) was established. It was determined that in plant communities removed from intensive pasture turnover, there occur a gradual restoration of layering, and an increase in species diversity of plants and in their abundance in communities. At the same time, an active introduction of pine to herbaceous (steppe) communities, consisting of plant species characteristic of the forest-steppe and steppe, was noted. It was found that the age composition of pine varies from 2-5-year-old individuals to 20-25-year-old trees represented by separate groups everywhere on fallow lands. It was noted that in the plots of fallows adjacent to a closed forest stand, there is a fairly closed undergrowth, regardless of the orographic features of the territory. A significant presence of plant species characteristic of zonal light coniferous forests was detected in the ground cover of such groupings. This is probably due to the early stage of formation of light coniferous taiga of zonal type. A restraining factor in the development of forests on fallow and steppe plots in the study area should be attributed to a possible increase in anthropogenic influences, mainly grazing regimes, due to the formation of farms. There are often periodic human-induced fires (“deliberate fires”) in order to preserve rangelands. Simple felling of pine undergrowth has also been noted, both in fallow lands and in adjacent territories. In many respects, this is of decisive importance for the possibility of formation and development of forests on post-agrarian territories in the near future.
|
