Desert acridian fauna (Orthoptera, Acridomorpha): Comparison between steppic and oasian habitats in Algeria.

Through monthly samplings of grasshoppers taken from five sites in oases and two in steppes in the area of Biskra, 45 species could be recorded. Four assemblages of species can be defined, two in the oasian zones, one in the stony steppe and a last one in the sandy steppe. The two oasian assemblages are interpreted in the light of a gradient of salinity and humidity determined by the vegetation. In each type of steppe, there is a spring sub-assemblage and a summer-autumnal one, but such a distinction is not possible in the anthropised sites. The steppe stations are moreover characterized by a larger diversity determined by the Shannon index and a weaker density than in the oases, in spite of a comparable richness. The comparative analysis of species phenology between the different assemblages allows discussing their adaptation toward seasonal variations of dryness in these arid environments.