World Congress of Soil Science Logo 18th World Congress of Soil Science
July 9-15, 2006 - Philadelphia, Pennsylvania, USA
International Union of Soil Sciences

Tuesday, 11 July 2006

This presentation is part of 28: 1.2A Spatial, Societal and Environmental Aspects of Pedodiversity - Theater

Unique and Rare Kinds of Soils on Samarskaya Luka (Middle Volga, Russian Plain).

Evgeniy V. Abakumov, Elvira I. Gagarina, and Natalia A. Rudenko. Saint-Petersburg State University, 16-line, 29, V.O., Saint-Petersburg, 199178, Russia

Russian steppe and forest steppe zones characterizes by a maximum degree of agricultural impact, strongly expressed arable land degradation and very low portion of undisturbed natural soils. Samarskaya Luka is the natural reservation with relatively undisturbed soil and vegetation cover. This territory is one of the biggest protected area (155 000 ha) in Middle Volga Region of Russian Plain. Investigated territory is unique macro landscape formation in the east part of Volga Upland presented by a peninsula surrounded by Volga river and artificial water reservoirs. There are two protected areas on investigated territory: Jiguli State Reserve and National Park “Samarskaya Luka”. Samarskaya Luka can be divided to three landscape parts: Northern mountain complex, Middle Uplands and Southern Plain with flat relief. These landscapes are known as refuge of rare and unique soil types and plant communities. The glaciations impact on relief formation was indirect, connected only with climatic changes. That is why soil cover and plant communities continuously develops during all Holocene period. The complicated history of landscapes development, weathering, tectonics movements, and transgressions of Caspian Sea leads to very big diversity of Quarternary substrata and parent materials, diversity of relief types and, consequently, strongly expressed differentiation of climatic conditions, especially in northern part. These factors causes a very big diversity of soils on investigated territory, formation of untypical soil combinations and complicated soil spatial distribution. Northern, mountain part is occupied by Rhendzic Leptosols under Pine forests with steppe gross cover. Limestone hinders the intensive changes in soil properties under the climatic fluctuation and therefore assists to stable existence of plant communities. Steppe communities under the forest canopy on the weak developed lime-containing soils are the most ancient type of landscapes on Samarskaya Luka. On the Northern foot slopes the typical soils is Cambisols. Its formation caused by climatic specifics on the slopes exposed to the Volga River. The thermoregulation effect of river and increased humidity assist to intensive weathering of soil mineral part and formation of humus with big portion of fulvic acids. Cambisols of Samarskaya Luka is unique for the conditions of continental climate eastern part of Russian Plain. Another type of soils in mountain region is Albi-Luvic Phaeozems, formed on the western and eastern slopes. These relief expositions characterizes by more dry and contrast climatic conditions. Soils shows evident features of clay illuviation, less degree of in-situ weathering, and increased intensity of organic matter humification. The Middle Upland plain shows the very untypical combinations of soils, caused by big diversity of bedrocks and parent materials. Umbric Albeluvisols and Gley-Histic Albeluvisols alternates with Albi-Luvic Phaeozems. Albeluvisols forms under the birch forests, Phaeozems are typical for linden forests. Albeluvisols spreaded on the acid clays and loams, meanwhile Phaeozems are usual soils for lime-containing loams, which cover the limestones and its debris. Luvic Chernozems are characteristic for meadow steppes and alternates with Umbric Podzols under the birch forests. Such unusual combination of soils is caused by properties of parent materials. Thus, Chernozems forms on loess-like loams developed from derivates of limestones. Podzols develops on acids sands wedged by little plots in cover of lime-containing parent materials. Typical steppe communities with Haplic and Glossic Chernozems occupy the Southern Plain of Samarskaya Luka. Here, the Haplic Chernozems occupies the loess-like loams, meanwhile Glossic type of Chernozems spread on the lime-containing sediments of Caspian transgression. Summarizing, we can conclude that on relatively small territory of isolated landscapes on Samarskaya Luka there is a very high diversity of soil types, caused by specific of geogenic factors. The relief influence is maximally expressed in mountain part, upland and plain territories shows more expressed influence of parent materials type on soil spatial distribution. Geogenic factors leads to differentiation of soil cover and formation of very contrast soil types, e.g. Podzols and Chernozems, Cambisols and Phaeozems, Albeluvisols and Phaeozems. In usual conditions of Russian Plain climosequence such combinations of soil types is unusual, that is why we can conclude that the geogenic factors is most important and leads to the correction of soil formation potential, i.e. all factors of soil formation became modified by relief and parent materials. Now investigated territory is partially protected. Northern mountain part is protected strongly, but the Southern territories are more antropogenically influenced and partially involved in agriculture. All landscapes of Samarskaya Luka need to be strongly protected not only in sense of flora and fauna, but also in direction of soils and soil cover, which can be classified as refuge of rare soils and natural etalon of Phaeozems and Chernozems for Middle Volga Region. The saving of investigated soil cover is very urgent for sustainability of nature in Middle Volga Region. Also there is a unique natural soil museum on the border of forest-steppe and steppe zones, which are characterizes by very intensive anthropogenic soil degradation.

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