SUBFOSSIL ORIBATID MITES IN THE PEAT DEPOSITS OF THE EUTROPHIC MIRE: SOUTHERN TAIGA OF WESTERN SIBERIA

The remains of subfossil oribatid mites have been investigated in nine peat layers of the eutrophic mire, located in the southern taiga ecological zone of Western Siberia. In total, 17 taxa have been revealed. Hydrophilic mites Limnozetes sp. and Hydrozetes sp. dominated all assemblages, which reflects an increased surface wetness of the mire during the entire period of its development (8,850 yr). Fluctuations in the surface wetness are expressed through changes in both the species composition and the relative abundances of species of oribatid mites. Decreases of surface wetness are accompanied by a decrease in the proportion of Hydrozetes sp., an increase in the proportion of Limnozetes sp. and in the number of species in the assemblage. DOI: 10.21684/0132-8077-2017-25-2-171-17

Late Glacial and Holocene vegetational changes on the Ulagan high-mountain plateau, Altai Mountains, southern Siberia

Three well-dated pollen diagrams from 1985 m, 2050 m, and at the tree line at 2150 m asl show the vegetational succession in the central Altai Mountains since 16 cal ka BP. Pioneer vegetation after deglaciation was recorded first at the lowest site. Subsequently, dense dry steppe vegetation developed coincident with the change from silt to organic sediments at the two lower sites, but silt lasted longer at the highest site, indicating the persistence of bare ground there. Forests of Pinus sibirica, Pinus sylvestris, Picea obovata, Larix sibirica, Abies sibirica, and Betula pendula started to develop about 12 cal ka BP with the change to a warmer and wetter climate at the beginning of the Holocene. Results indicate that the timberline did not rise above the highest site. Mesophilous dark-coniferous forests were fully developed by 9.5 cal ka BP. The role of Abies and Picea decreased by about 7.5 cal ka BP suggesting cooler climate, after which the forests changed little until today. The vegetational development in this portion of the central Altai Mountains is compatible with that described in neighbouring areas of the Altai, southern Siberia, Mongolia, and Kazakhstan