Environmental determinants of the composition of desert-living rodent communities in the north-east Badia region of Jordan

Abstract

The spatial and temporal compositions of rodent communities in habitats of the Badia region of north-east Jordan were investigated between 1996 and 1997. Live grid-trapping and spot-lighting techniques were employed to estimate rodent densities. Sixteen environmental variables including soil content, vegetation cover and relief were recorded within the study sites. TWINSPAN was used to derive six habitat classes based on the similarity of their rodent communities. These were hammada, harrat, marab, wadi and two types of sand dunes. The derived classifications were similar to the original categorization of habitat types based on ground-truthed observations of the sites selected from satellite imagery. Multivariate statistical analyses (TWINSPAN and DECORANA) revealed three major rodent groups in relation to local habitat types: (1) petrophiles: Gerbillus dasyurus, Acomys russatus and Meriones tristrami; (2) open hammada-dwelling species: Jaculus jaculus, Gerbillus henleyi and Meriones crassus; (3) psammophiles: Meriones libycus, Gerbillus nanus and Gerbillus cheesmani. Species richness was highest in marabs and lowest in red sand dunes. Species diversity (Hill's index) was highest in sand dunes and lowest in red sand dunes. Rodent biomass was highest in sand dunes and lowest in wadis. CANOCO showed rodent community composition to be correlated with vegetation parameters and soil content. TWINSPAN grouping and DECORANA ordination of rodent species provides some evidence for habitat preference, size disparity and competition as mechanisms of resource partitioning facilitating coexistence.