Diversity and distribution patterns of iand snaiis in the arid region of Batna (North East Aigeria)

摘要

The aim of the present study is to describe the diversity and to evaluate the pattern distribution of land snail populations that colonizing a natural environment in arid area of Batna region, in the North eastern part of Algeria. The species samplingwas performed weekly throughout the spring period of the year 2013, using Barber pots and sight hunting in parcels of spontaneous vegetation. The study area was represented by four sites, selected following the gradient of aridity; from the less arid tothe most arid. The sites are named, station 1 is Batna proximities, station 2 is Lambiridi, station 3 is El Ghadjatti and station 4 is Ain Touta These stations are a mosaic of landscapes including woody mormtain lands and in the vast majority, plains characterized by a variety of cultivated areas. The systematical study of 604 collected individuals revealed the presence of 11 species of terrestrial pulmonates belonging to four families: Helicidae, Zonitidae, Subulinidae and Sphincterochilidae. The occurrence frequency shows that the most constant species are: Helicigona lapicida (C = 71.43%) and the less constant species is Cantareus apertus (C = 3.57). The lowest similarities are noted between station 4 and stations 1 (57.14%); and 2 (47.14%). The total specific richness is highest in St 1 (8 species), while the St 4 is the least rich (5 species). It was found that the species of Zonitidae were predominant with (47.52 %) and the site 3 was the most diversified with H' = 2.27 bits. The ANOVA test shows that except four species {Cepaea hortensis, Cantareus apertus, Rumina decollata and Sphincterochila candidissima ), the others eight population dynamics varies significantly depending of the studied stations. However, the temporal variation of populations is statistically insignificant. We concluded that the diversity of land snails is influenced not only by the degree of aridity, but also by the type of habitat and the particular presence of limestone.