Distribution patterns of plant communities along the Kholbon - Mogocha transect (Southeastern Transbaikalia)
I.G. BORISOVA, T.N. VEKLICH
Amur Branch, Botanical Garden-Institute, Far Eastern Branch, Russian Academy of Sciences, Blagoveshchensk, Russia
Keywords: plant communities, cartographic method, gradient analysis by ecological factors, zoning
Abstract
This study used the cartographic method of research and gradient analysis on environmental factors. A zoning of the transect into landscape-geomorphological areas has been completed. The following areas were identified: mountain light coniferous taiga (Berezovaya River - Mogocha), mountain subtaiga (Ulei River - Zhirekent - Aksenovo - Zilovskoe - Berezovaya River), and mountain forest-steppe (Kholbon - Nerchinsk - Chernyshevsk - Ulei River). They differ significantly in composition, structure and spatial combination of plant communities. Steppes are the predominant type of vegetation in the mountain forest-steppe. They occupy 60 % of the territory. Forests are represented by birch forests and occupy 12 %. Riverside thickets and meadows predominate in the valleys. Anthropogenically transformed vegetation occupies large areas. Light coniferous forests and their derivatives occupy more than half of the territory (64 %) in the area of mountain subtaiga. Pine and larch-pine forests are also common here in small areas. Steppes occupy steep southern and southwestern slopes (about 3 % of the study area). Shrub-birch-willow-shrub moss-grass thickets are characteristic communities of the site and occupy high floodplain terraces and long piedmont plumes (6 %). The riverine rows of plant communities become more complex. Forests occupy more than half of the site (53 %) in the mountain light coniferous larch taiga. Mari is widespread (30,9 %). Dry xerophytic-herbal communities with shrub grow on very steep and well-heated slopes. Their area is less than 0,5 %. Floodplain forests acquire a taiga character in the valleys. Characteristics of the habitat of plant communities according to the complex of ecotopic factors are given. These are heat supply, soil richness, soil moisture, soil carbonate content, and cryo-conditions of soils.
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