Аннотация:Applying the systems approach and GIS technologies for providing a framework for soil classification is discussed. According to the systems approach, soils can be considered in two ways: as self-sufficient systems consisting of genetically interrelated horizons, and as derived elements of systems of higher order - natural landscapes-systems (referred to below as 'landscapes') which are minimal structural units of the earth’s landscape envelope. Soils come into existence through the interaction of the basic landscape elements - rocks, air, waters, and organisms. This is an essential character trait of soils. All landscape elements are material substances with homogeneous properties. There are landscapes with and without soils. Soil-free landscapes are formed in cases when properties of one or more basic elements prevent soil forming processes. In our view, consideration of soils as derived elements of natural landscapes has paramount importance for their classification.
It is known that soil classification and mapping, primarily small-scale one, are closely interdependent. Soil mapping is the process of classifying soils. Soil classifications serve as a basis for legends of soil maps, at the same time they draw on and are corrected in accordance with the results of soil mapping. Adequate choice of soil classification criteria is possible only in the process of mapping. Therefore soil classification and mapping are inseparable and must be carried out simultaneously in a single process. This is especially the case for global multiscale soil mapping for the purposes of world soil classification. We have begun to test the systems approach to soil classification using traditional compilation method at first stage and GIS technologies on the next one. The territory of the European Russia (excluding mountains), the Saratov region (RF), and some of municipal districts and farm units of the Saratov region were chosen as pilot areas. Scales of geographical base maps are, and are to be, 1:7,500,000, 1:2,500,000, 1:500,000, 1:100,000, and 1:10,000. Then as far as possible mapping at scales of 1:20,000,000 and 1:5,000 or smaller/larger will be initiated. In the process of the research maximum possible quantity of available thematic and geographical maps (such as geological, Quaternary sediments, geomorphological, agroclimatic, landscape, soil, hypsographical, topographical, and maps of vegetation), text, and remotely sensed data sources are used. Criteria of a world soil classification based on the systems approach are separate or conditional basic landscape element properties which are directly responsible for the fundamental and conservative soil properties. Initial level of the classification is represented by the earth’s landscape envelope - a set of natural landscapes with and without soils. In the process of the classification all landscapes and, accordingly, soils are gradually divided into subdivisions of different hierarchical levels and branches of the classification tree unless reaching separate (individual) landscapes and soils with homogeneous properties. An illustrative list of possible criteria to be used at the higher levels of the classification system is the following: a vertical combination of landscape elements (according to this criterion landscapes and soils are divided into terrain and water bottom ones); type of megarelief - range of altitudes and slopes (the criterion allows to divide landscapes and soils into plain and mountain ones); location on the leeward or windward side of piedmonts; zonal vegetation in connection with macroclimate - effective heat sum and precipitation ratio; presence/absence of seasonal flooding from a river; forms and genetic types of macrorelief in connection with geological structure; genesis, lithology and texture of parent rocks; chemistry and salinity of ground water. Hierarchy of criteria and criteria themselves can vary for separate branches of the classification tree. The process of delineation of landscapes with soils is controlled using information on spatial distribution of soils and their properties. Mapping units in GIS are labeled by unit identification codes which serve as connecting links between them and the classification. For ease of use, the classification is created as interactive.
From the result of the research, the following two main conclusions can be drawn: (1) the systems approach gives directions for the construction of supra-national world soil classification as a part of world landscape classification; (2) the construction of world soil classification based on the systems approach is possible only in the process of multiscale GIS soil-landscape mapping.
Keywords: world soil classification, the systems approach, landscapes-systems
soils as landscape elements, world soil-landscape classification, multiscale GIS mapping