Earthworm effect on invertebrate community under Olive tree ecosystem in Semi-arid Region of Algeria

The biodiversity of the invertebrate community in the soil is greatly influenced by the presence of earthworms, which are also influenced by variations in the physicochemical and biological characteristics of the soil as well as the climate and the entire ecosystem that surrounds it. Biodiversity under an olive tree growing in a cold semi-arid climate with specific agricultural practices is the subject of this study, while highlighting the particular effect of earthworms on invertebrates collected by naked eye and by the Berlese extractor from a soil volume of 30cm3, in ten sites under the adjacent periphery of olive trees randomly designated from an orchard of 45 years old in Ain Touta region in eastern Algeria in spring period of 2020 years. A large variability in the diversity and evenness indexes is recorded between the study sites. It reached a value of H'= 1.78 and E = 0.85 at site where there is a greatest abundance of earthworms. The dominance index is between C=0 and C= 0.12. The results show a greater number of earthworm with an average of (130.00 I/m2±69.10), and average biomass of (83.36 g/m2± 53.31). The percentage of juvenile is higher than adult worms. Pearson correlation matrix reveals a strong negative effect of adult worms on Acari with -0.90, then on the Carabids with -0.74. The principal component analysis allowed a finding of the significant effect of adult, the abundance worms and their biomass on Acari, Carabids and small Dipteran larvae.