Probabilistic Assessment of Contemporary Soil Evolution in the South of Western Siberia Based on Analysis of Soil Monitoring Data

Abstract

The aim of this article was to introduce a new general and theoretical approach to the probabilistic assessment of contemporary soil evolution (CSE) by analyzing soil monitoring data. The CSE is considered a continuous block process of change in soil conditions over a period extending from 10 to 100 years. The soil condition is considered as its position in the range of n soil properties in k soil horizons. As previous investigations have shown the essential intrinsic changeability of soil properties in this range, even in homogeneous objects, my proposed idea to assess CSE was to evaluate changes in the probability distribution functions (pdfs) of soil properties at different moments in time. Taking into account soil variability at different scales, I have introduced three categories for the spatial changeability of soil properties. Assessments of the variability of soil properties at the field level are of most importance for the evaluation of CSE. This variance is presented as the sum of variances induced by elementary soil processes, the micro- or meso-heterogeneity of factors of soil formation and elementary landscape processes, distinctions in the anthropogenous factor, and how the soil reacts to them. I developed a method that consists of (1) identifying the pdfs of soil properties, which means a quantitative evaluation of the kind and parameters of pdfs according to data samples resulting from soil investigations; (2) calculating probabilistic indicators such as the statistical entropy of pdfs as probabilistic characteristics of soil status and informational divergence that is a measure of pdf difference. A case study has been done on the large territory in the south of Western Siberia. New findings were the changes in the probability structure of Kastanozem soil properties during CSE under natural processes and anthropogenous influences. Distinctions in pdfs were evaluated from the values of informational divergence and increment in statistical entropy, which were quantitatively different for soils of different granulometric composition, that is, useful to point out the most vulnerable soils in the territory under investigation. It may be concluded that it is necessary to use probabilistic indicators to assess CSE from pdf alterations. They characterize a degree of influence of soil-forming factors and anthropogenous influences on the probability structure of the properties of a soil and its stability. Thus, they could be reliable indicators of environmental transformation, that is, important for land resources research, land use policy planning, and basic research.