Mapping of reference area representativity using a mathematical soilscape distance

The applicability of detailed soil surveys limited to small reference areas to larger regions should be assessed using easily available data. This is done in this paper by computing at each site of the large region a mathemat ical distance between local soilscapes and those in the reference area. Soi lscapes are represented by a cover frequency vector of elementary landscape classes (combinations of soil-forming factor classes) calculated within an area defined around the site under consideration, The application of this technique to four reference areas located in the Herault-Libron-Orb valleys in the south of France demonstrated that: (1) the proposed soilscape dista nce was in good agreement with the degree of representativity of a referenc e area (i.e. percentage of soil classes already encountered in the referenc e area), (2) representative areas of different size and purity can be delin eated from a soilscape distance map by applying a distance threshold, (3) e xpertise in delineating a reference area has a strong influence on its perf ormances, i.e, size vs. purity of representative area. This suggests that t he soilscape distance tested in this paper could be integrated in a classif ication procedure defining the optimal size and location of future referenc e areas. (C) 2001 Elsevier Science B.V. All rights reserved.