Contribution à l’étude des peuplements lombriciens du Djebel Bou Taleb (Sétif, Algérie)

Abstract

Earthworms, key soil engineers, remain poorly documented in the semi-arid environments of Algeria. This study addresses the demoecology of earthworm communities of Djebel Bou Taleb (Sétif, Algeria), a transitional massif under an upper semi-arid bioclimate with a cold variant. The aim is to characterise the structure and species composition of the community across three stations (Aras, Aïn Bebe, Aïn Aneb) and to relate its distribution to soil physico-chemical properties. During the semihumid period, six pits (30 × 30 × 30 cm) were hand-sorted; moisture, porosity, bulk density, pH, electrical conductivity and total carbonate were measured. Thirteen individuals were collected, with half of the pits empty. Identification, restricted to the five adults, revealed three species — Octodrilus complanatus, Aporrectodea rosea and Lumbricus terrestris — i.e. two anecic species and one endogeic, with no epigeic; the eight juveniles (61.5 %) remained undetermined. The anecic species are confined to Aras, on the most calcareous and least conductive soils; the endogeic occupies an alkaline pit at Aïn Bebe; and Aïn Aneb, the most saline station, is devoid of worms. After correction, densities reach 22–67 ind/m² and biomass 18–37 g/m². Species distribution follows an edaphochemical gradient, calcium availability and low conductivity favouring the calcicole anecic species. Despite a limited effort precluding statistical inference and an identification restricted to adults, the study provides a novel faunistic contribution for an unexplored massif and confirms the bioindicator value of earthworms in semi-arid environments, calling for multi-seasonal monitoring and molecular barcoding.