Abstract
The sequence extends from an elevation of 10 m to 2200 m. All told, 220 soil profiles were studied. These soil profiles were grouped in the French classification system.The morphology of the profiles permitted definition of eight “referencelrd horizons. For these horizons, 58 pedogenetic variables were defined from the results of physical and chemical analyses.For each profile the following environmental variables were defined: vegetation level, vegetation formation and lithological type of calcareous parent material.The pedogenetic difference between two profiles was measured by a taxonomic distance based on the presence or absence of the “reference” horizons and on the differences between common horizons. The distance between every pair of profiles are summarized by a phenogram with a fitness which commonly is higher than 80%. The groups of the phenogram are in turn summarized and discussed at five levels of synthesis, each grouping explained by the discriminant power of the pedogenetic variables and by the discriminant power of the environmental characteristics. Furthermore, the agreement between the numerical classification and the French classification is measured by the discriminant powers of French classification groups and subgroups.The first and second level of synthesis show three large groups: 1.(1) Soils that are very weakly developed. These soils are very shallow. In this subdivision fall all the rendzina soils, part of the humic carbonates soils (sols humiques carbonatés) and part of the litho-calcic humiferous soils (sols lithocalciques humifères) of the French classification.2.(2) The soils without a calcareous reserve. Three subdivisions are present: 2.1.(a) The soils of the first group are in complete agreement with the fersiallitic soils without calcareous reserves, formerly called Mediterranean red soils (sols fersiallitiques sans réserve calcique) in the French classification. Their exchange complex is slightly to moderately unsaturated, their pH is neutral and they all are leached.2.2.(b) The second subdivision also consists of leached soils, but these have an acid reaction and their exchange complex is mainly desaturated. This subdivision is made up podzolized; it includes the largest share of the modal leached soils (sols lessivés modaux) of the French classification. The other subgroup includes soils that are slightly leached but more podzolized.2.3.(c) The third subdivision consists also of acid soils with an exchange complex very desaturated but they are not leached. This subdivision coincides with the modal brown (sols bruns modaux) and the acid brown (sols bruns acides) soils of the French classification.3.(3) The soils with calcareous reserve. This group has three subdivisions: 3.1.(a) The first one is made up of very organic soils of the humid mountain Subalpine and Alpine vegetation levels. These soils are subdivided in two subgroups which differ in the nature of organic matter.3.2.(b) The organic matter content of the second subdivision is lower. All of these soils are saturated and have a neutral pH in the A1 horizon. They correspond mainly to calcic brown soils (sols bruns calciques) of the French classification. The two further subdivisions of this group are one including soils with a calcareous (B) horizon and another with a calcic (B) horizon.3.3.(c) The last great subdivision coincides with the fersiallitic soils with calcareous reserve (sols fersiallitiques à réserve calcique) of the French classification (formerly red Mediterranean soils) found on hard limestone under Mediterranean conditions. All these soils are saturated to slightly calcareous and have an A1 horizon with alkaline pH. They are subdivided into typical fersiallitic soils and fersiallitic soils with a BCa horizon.Leaching (lessivage) of clays and of sesquioxydes occurs under very different conditions, and four are identified. Moreover, the environmental conditions on which the fersiallitic soils are found are indicated.
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