TERRESTRIAL ISOPODS DIVERSITY RELATED TO IRRIGATION AND AGRICULTURAL PRACTICES IN NORTH-EAST OF TUNISIA

Abstract

Environmental factors and land-use affect soil biological communities and their functions. Terrestrial Isopods (woodlice) are detritivorous and reliable bio indicators of habitat quality and soil capacity production. In order to evaluate the effect of different irrigation practices, woodlice richness (S), diversity indices (H’ and J’) and their relative abundance (A) were studied according to 3 types of irrigation (drip, surface mode and sprinkler) in 16 plots and 9 different types of cultivation: market gardening (artichoke, tomato and melon); vegetable crop (alfafa, sorghum and maize) and fruit-trees (apple, pear and olive) in the Majerda low plain (North-East Tunisia). Pitfalls were used to collect woodlice during 3 weeks (from 22nd August to 09th September 2008). Physico-chemical analyses were performed from soil sampled in each plot. According to the type of irrigation, 7 species of terrestrial Isopods were listed and their richness (S) was very important in the case of sprinkler. The mean relative abundance of Porcellio laevis was very important when the surface mode of irrigation was used. For both Porcellio variabilis and Porcellionides sexfasciatus it was respectively with sprinkler and drip. Both Shannon’s diversity and Equitablity indices were higher with the sprinkler mode. According to the type of cultivation, species richness was higher in the alfafa and maize cultivation. Porcellionides pruinosus, Chaetophiloscia. elongata, Armadillidium sulcatum and Leptotrichus panzeri were the less abundant in each type of cultivation. The mean Isopods diversity revealed that their diversity was higher in the sorghum cultivation. Moreover, a relationship between the soil features and a relative abundance of terrestrial Isopods was described.