Features of recent mineral substance accumulation in oligotrophic bogs of the southof the forest zone of Western Siberia

There are practically no data on the rate of mineral substance accumulation (V_ac of MS) in the bogs of Western Siberia. However, its variation must be considered in geochemical, hydrochemical and ecological researches. Recent mineral substance accumulation was studied in 32 oligotrophic low-pine ericaceous dwarf shrub Sphagnum fuscum biocenosises (ryams) and swamp biocenosis of 9 bogs located in the southern taiga and subtaiga of Western Siberia. Peat samples were taken from 37 peat monoliths with the step of 1-3 cm. Analyses of macrofossils plant remains, peat decomposition degree, ash contents and dry bulk density were made in each peat sample. Monoliths were dated by Cs and ash content extremums, which correspond to the year of 1963. The recent average rate of MS accumulation was estimated for the last 40-45 years and its significant variation (30-166 mg/dm yr) was revealed. It was determined that maximum V_ac of MS (127-166 mg/dm yr) are characteristic for biocenoses of bogs, which bed on sand and have catchments, which were repeatedly exposed to fires. The dependence of recent V_ac of MS on the response of biocenoses to interdecadal climate changes was revealed. The degree and trend of the response depend on the initial water regime and define V_ac of peat and the activity of MS transferring from lower lying peat layers and its accumulation in roots of pines and dwarf shrubs. For ryams and swamps of the bogs, which bed on clay and loam, V_ac of MS varies mainly from 78 to 63 mg/dm yr. Higher V_ac of MS (96-126 mg/dm yr) is characteristic for most dried ryams with forest litter from Pleurozium schreberi; for ridges and hollows of flowing channels and primary lakes quagmires with more mineralized waters; for peripheral ryams, being final links of geochemical catena or recently passed to oligotrophic development stage. The minimum V_ac of MS (50 and 41 mg/dm yr) is characteristic for ryams with rare layer of dwarf shrub and low density and V_ac of peat; for regressive ryams with partial loss of aerosols; and for overgrown secondary pools (30 and 38 mg/dm yr) with low peatdensity and active loss of MS. Recent V_ac of MS in biogeocenoses of the investigated bogs depends on lithology of the surrounding territory, their location in bog massives and on a certain element of meso- and microrelief, which define the kinds and the ratio of mineral nutrition sources and intensity of MS loss, and also on initial species composition and structure of biogeocenosis and its response to the climatic changes, defining V_ac of peat and intensity of transfer of mineral substance from lower lying peat layers.

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