Pedodiversity and global soil patterns at coarse scales (with Discussion)

Several algorithms for analyzing the diversity of the world pedosphere are reviewed and employed. Special emphasis has been laid on indices based on the Theory of Information. We study the diversity and distribution of major soil groups by continents and climatic zones on the basis of data compiled by the FAO at the scale 1: 5,000,000. Major soil group-distribution model relationships on a world level seem to follow more equitable patterns than those established for biocenoses and soil patterns at fine scales. At a continental level, the pedosphere's diversity is characterized by similarities rather than differences. Differences in diversity by climatic zones are more marked. Evenness (Pielou's index) and diversity (Shannon's index) tend to be greater in the climatic zones of intermediate latitudes than in circumequatorial and circumboreal latitudes. The climatic zones closest to the Poles could be the planet's most uniform soil patterns at small scales. Mountain areas, in general, achieve the highest pedorichness and lowest values of diversity. Global soil pattern distribution was also analyzed using multivariate techniques. At a continental level, it is possible for the structure of the global pedosphere to be determined by the continent's geological, tectonic and climatic histories. Soil patterns of different climatic zones are linked in a very well-defined latitudinal gradient.