Early stages of vegetation cover formation in the nivationsnische of the Kuraiskiy ridge (South-Eastern Altai)

The studies which were carried out on the watershed of the Kuraiskiy Ridge in South-Eastern Altai at the headwaters brooks: the Ortolyk and the Kurayka (the basin of the Chuya), the Right Kubadru (the basin of the Bashkaus). The altitude of the Kuraiskiy ridge are close to the modern level of "snow line". This determines the existence of a large number ofsnowfields, which persistfor a part of or all warm period. As it is known, snow cover is one of the most important factors of exogenic relief forming in a high montane zone. The presence of snowfield leads to intensive washing out of small particles and their deposition down the hill. During the development (deepening) of Nivai-tonsnische, the mass of accumulated snow increases and the slope becomes less steep. As soon as the bed humidification becomes relatively constant, hygrophilous green mosses take up residence on the edges of many brooks. Among them dominates Cir-riphyllum cirrosum (Schwagr.) Grout which amounts up to 50% of moss turf. This moss, dominating in marginal parts, determines the rate of turf proliferation. Philonotis to-mentella Mоl. and Bryum schleicheri Schwaegr., the abundance of which is 20-25%, play an important role. In central most humid parts of turf along with Cirriphyllum cirrosum (Schwagr.) Grout. Together with them Brachythecium turgida (Hartm.) Kindb. and Calliergon trifarium (F. Weber & D. Mohr) Kindb are constantly encountered. In dry off parts, at strong oppression of Cirriphyllum cirrosum, take up residence Rha-comitrium canescens (Hedw.) Brid., Drepanocladus uncinatus (Неdw.) Wаrnst., Ce-traria cucullata (ВеНапИ) Ach., as well as in the most arid places - Scorpidium turge-scens (С. Jens.) Моеnk. Among flowering plants, aracolpodium altaicum (Trin.) Tzvel., Dichodon cerastoides (L.) Reichenb and Saxifraga sibirica L., which provide up to 95% of the projective cover, dominate. The first two species are very numerous and its thin and long shoots permeate practically all mossy turf. The involvement of other species of plants is insignificant. The continued growth of moss turfs leads to slower water runoff and an increase in its level; this initiates moss turf overgrowth broadwise. At this stage of Nivaiton-snische, the vegetation cover is a complex mosaic of incipient low power moss turfs and gravelly-sandy clay exposed areas, which are occupied by pioneering groups of flowering plants (Eritrichium villosum, Gastrolychnis apetala (L.) Tolm. et Kozhanczikov, Minuartia biflora (L.) Schinz et Thell., Cerastium lithospermifolium Fischer, Saxifraga sibirica, Cardamine bellidifolia, Chorispora bungeana, etc). The further flattening of the surface and overgrowth of moss turfs leads to the oversimplifying of the horizontal structure of vegetation cover and the strengthening of the role of tundra-moss-marsh coenotic complex plants.

Keywords

Authors

References