Reconstruction of regional dynamics of forest cover on dry lands of the central Sym-Dubches interfluve in the middle and late Holocene

Abstract

The successions of the species composition of the dry land forests as well as the climate of the central part of the Sym-Dubches interfluve were reconstructed on the base of the layer-by-layer spore-pollen and radiocarbon analyses of bog sediments in two profiles. The analysis of the species composition of tree pollen and its percentage ratios in the spectrum made it possible to distinguish palynological zones and based on them to reconstruct the main stages (phases) of forest cover in the Middle and Late Holocene. It was established that in the second third of the Atlantic period the pine and birch forests mixed with spruce Picea A. Dietr. were developed on dry lands, and at the end of the period – the pine and birch forests with fir Abies Mill. and spruce were developed. During subboreal period change in the species composition of the tree stands as well as the development of pine-Siberian stone pine-birch and spruce forests took place. In the Subatlantic period the zonal taiga forests with dominance of two species – pine Pinus L. and Siberian pine Pinus sibirica Du Tour – grew on dry lands. Birch, spruce and fir species had a subordinate importance in forest formation. It was established that the regional features of the study area substantially leveled out the paleoclimate parameters what resulted in smoothing out the thermal maxima and minima, which are specific for the Western Siberia. We assumed that the successions of forest ecosystems occurred not only as a result of the Holocene climate fluctuations, but also as a result of their self-development.

Keywords

• peat deposit
• spore-pollen analysis
• radiocarbon dating
• reconstruction
• palynozones
• phases of forest cover
• successions of dry-land forests