Les peuplements de Fourmis et les peuplements d’ Acridiens du Mont Ventoux. II. Les peuplements de Fourmis

Abstract

The composition of the ant communities and the relative frequency of each species are described, as well as their ecological and altitudinal amplitudes. The richness and/or the composition of the communities differs from one vegetation zone to another. All the communities show a very hierarchical structure. The Shannon eaver index of evenness is roughly equal in all communities. The communities are very varied, but three species are predominant over the mountain : Lasius niger, Tetramorium caespitum and Formica lemani. Of the environmental features, temperature is the most important, producing a marked altitudinal zonation of species and communities. The effects of aridity are important among certain species, leading to vertical discontinuities in their ranges. The vegetation cover affects species dependant on particular plants ; these species have been considerably affected by reafforestation, especially on the lower parts of the southern slopes, leading to a notable increase in L. niger. At the summit, the main limiting factor is temperature on the northern slope ; and the dessicating effects of the winds on the southern slopes.