A method for a clearer arrangement of large amounts of data, in particular soil inventory data, is described. The method is based on the transformation of measured values into (e.g. 10) graduated classes, each of which is to contain about the same number of values. Each paramter of a complete soil profile is then assigned a number between 1 and 10 so that soils having a similar chemical composition can easily be clustered and different soil inventory systms can be compared without problems. in this paper the data obtained from the Austrian Forest Soil Monitoring System will be used to describe the principles of such a concept and to explain and substantiate the individual steps of a data condensation method. Two goals are to be pursued simultaneously: On the one hand, groups of sample plots characterized by maximum homogeneity, or uniformity, i.e. clusters, are to be selected from a totality of items, in this case from the totality of sample plots used in soil inventory systems. On the other hand, the position of our own results relative to other, similarly structured investigations is to be determined. The choice of an appropriate unit of distance or similarity, the form of the data transformation as well as the selection of the parameters, or combinations of parameters, to be computed will influence the quality of the results. The method will permit us to check sample plots or sites characterized by particular chemical properties and to present them in the form of maps. Sites which are uniform from a chemical point of view can then be compared to (individual or combined) results of other investigations (for example the mineral content of needles/leaves and/or the pollution situation). If, for instance, data specifying the concentrations of particular elements in needles have been transformed and computed in a similar manner, the soil and plant interactions should be particularly evident. It is expected that the use of this condensation method and its intermediate steps will facilitate the investigation of ecological interaction.
