ABSTRACT
158The Soil Science Department of the French National Institute for Agronomic Research is currently undertaking a test to better understand and formulate the arrangement of soils in landscapes, no longer done solely on soil definitions according to various taxonomies or referentials, but based on the relationships between the main components of the soil cover. Our approach stresses a three-dimensional and spatial view of the soil cover. We introduce the concepts of Soilscapes and Soil-systems and discuss their usefulness in landscapes where the functions of the soil cover can be detemined. The first part of the paper reviews the concepts of Soil Cover and Soilscape, followed by comments on recent developments in taxonomic and cartographic fields, stressing the introduction of modern techniques. We then summarize the most current ideas of French pedologists on the use of spatial analysis in pedology. This is based on the analysis of successive organizations of soil components in the continuum of the Soil Cover in the landscape, leading to the notions of “soil typological units,” “soil mapping units,” “soil functioning units,” and “spatial organization models of soils.” We also discuss the feasibility and advisability of classifying different soil sequences on the basis of the dominant pedogenetic factors involved in their differentiation (e.g., relief for toposequences, parent material for lithosequences, time for chronosequences). Finally, we detail an approach that progressively builds an actual typology of the main Soilscapes in the French territory. Priority was given, for perhaps the first time, to toposequences within catchments in which the functions of the soil cover can be at least partly determined, and which can be considered as Soil-systems. Three examples from representative areas of the French territory are described: a loessic region of the Paris Basin, a detritic zone of the Centre, and a mountainous granite area of the Vosges Massif. These examples represent a first application of a new typology of French Soilscapes, which could therefore be based, in the first instance, on geomorphological and lithological parameters. An attempt to extend the representativeness of the three presented Soil-systems has been carried out. The basis has first been a delimitation of watersheds with DEM, combined with dominant parent materials selected from the Geographical Soil Database of France. The present work remains to be completed and validated. However, this general approach is being applied to other important natural regions of the French territory. In conclusion, the definition of Soilscapes and Soil-systems makes it necessary to consider all of the parameters used in soil taxonomy. There is a strong linkage between the proposed approach and the different soil classification systems.
