Some aspects of a multidimensional analysis of the evolution of ecological-geochemical soil state

Abstract

Soil saturation index and its calculating are demonstrating multicollinear correlations between ecological-geochemical soil state and environmental circumstances. There are wood ecosystems on the research area with Phaeozem, Luvisol, Retisol and Fluvisol. We have also studied the buried soil. Their burials occurred as a result of natural processes (about 5000 BP) and as a result of human impact (about 1000 BP). Age of separate genetic horizons (from 360±50 to 1870±160 ВР) indicates soils genesis during the last stage of the Holocene – Subatlantic. In our opinion the dynamics of the climate during last stage of the Holocene is the main cause of the complex structure of the soil cover on quite small area (5 km2). Second reason is difficult geomorphological environment (rough topography). On the basis of factor analysis proved efficiency of soil saturation index by trace elements: analytical work only with the indicated index reveals an unambiguous reduce the number of determining factors (up to two) and, thus, the proportion of the variance, which is determined by two factors is 100 %. While the using in the analysis of the total content, or a mobile forms of trace elements, or of some and the others together as a combined using of content mobile forms and their mobility will lead to an increase factor up to four and the simultaneous decrease in the proportion of the variance which is due to these factors to 74–88 %. We did not find decisive influence of any factor on saturation of studied soil types by trace elements. There is always a combination of processes that contribute to the accumulation of trace elements and processes of their migration. There are illuvial and lower transition to soil parent material horizons of the background content of trace elements for all investigated soil except Fluvisol (S-1). Belong to actual places of trace elements accumulation, which is generally quite small are some lower soil horizons both buried soils and lower transition to horizon of soil parent material (in soil R-3). Thus, the upper parts of the soils which were formed during the last centuries (780 years of age to today dated) are characterized by dissipation of most of trace elements. The genetic features of Fluvisol (S-1) have confirmed very high correlation. These features are the result of the genesis of this soil under the influence both soil and sedimentation processes. This is well illustrated in the analysis of the structure of the soil profile, which have characterized by stratification (during soil formation has not resulted in the development of any diagnostic subsurface horizon) genetic horizons and the presence of buried after the accumulation of alluvial material as a humus, as a transitional horizons. Perhaps, it is partly confirmed by the radiocarbon analysis, this soil should be regarded as younger age, which obviously explains persistent inflow of fresh materials. All other soils including the buried ones were formed under various elementary soil formation processes. These processes have replacing each other in time did not stop, and the normal evolution of the soil profile took place to bottom, in contrast to the fluvisol which evolution was to upper as have happened by the fresh alluvial and probably deluvial sedimentation. Recognizing of the «normal» soil genesis process as a basis for the formation of zonal soils in the Holocene, we are interpreting Factor 1, conducted by the context of factor analysis, as the environmental conditions for such soil formation. The results of factor analysis regarding to ecological-geochemical soil state Factor 1 should be considered as the basic parameters of soils (soil organic matter, pH, indicators of soil absorbing complex, mineralogical composition and particle size distribution). Under this condition Factor 2 is associated with the processes (fluvial, sedimentation, erosion) denudation, or transfer and accumulation of different material that would cause disturbance "normal" soil genesis. For that reason ecological-geochemical soil state is determined by soil formation factors for a specific time stage and dominant conditions for some processes.