Abstracts of Symposium 55 and some papers from other related Symposia.

Paleosoils: Indicators of Environmental Changes in the Holocene

Igor V. IVANOV. Institute of Soil Science and Photosynthesis RAS, 142292, Pushchino, Moscow region, Russia.

According to Dokuchaev V.V. "the soil is the mirror of landscape". The dependence between soil formation processes and climatic changes (thermal conditions, humidity) has been established. A particular significance in the soil formation is attached to biota, parent material, to a period of pedogenesis as well as correlation between the latter, denudation and accumulation processes. All of this well presented in the soil maps when determining natural zones, soil conformities and soil formations, soil-climatic facies, types and subtypes of soils. In a number of cases one can follow direct mathematic correlations between these dependencies. Diversity of modern pedogenic conditions and soils makes it possible to do such analysis for different natural conditions.

The determinal dependences soil-environment can be widely used for a detailed inspection of natural conditions in the Pleistocene and Holocene.

The experience gained on studying buried soils of Russia and the CIS countries in the Holocene shows that paleoclimatic conditions can be reconstructed by buried soils for various the Holocene chronocuts rather accurately. In thermal optimum of the Holocene due to the great temperature increase in respect to the rainfalls the optimal ratio between heat and humidity on the territory of the South Taiga and forest-steppe of Eastern Europe was lacking. In the steppe zone of Eastern Europe the ratio between heat and humidity was for formed to be optional due to increase of atmosphere humudification. The raise of subsoil waters in the non-drained semiarid and arid plains was observed. The time for short-term pluvial episodes in deserts was defined for Subboreal period. The subtropical zone in the deserts of the Middle Asia during the temperature optimum of the Holocene proved to be more extended. The steppe soils was established to suffer different pedogenesis and denudation for the last 5 millenniums. The rate of creep, peat accumulation and arid denudation was determined by changes in the soil properties for separate chronocuts. The VII-XIII centuries (Viking's time) were characterised by aridity intensification. The changes in properties of the soils buried under barrows enable us to elucidate the favourable and crisis epochs in the life of ancient tribes on the territory of Modern semiarid zone of Eurasia for the last 5 millenniums.

The work was done under support of Russian Fund for Fundamental Investigations and of International Science Foundation "Cultural Initiative".

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