Habitat relationships of the lizard fauna in the Ramon erosion cirque, Negev Highlands (Israel)



Lizards were censused in the Ramon erosion cirque (Central Negev. Israel) in 1994 on 24 one-ha plots. Fifteen quantitative habitat variables, describing soil and vegetation structure, were measured at 25 points of each plot. Data were analysed to examine a classification of habitat types based on lizard species composition and the sets of environment variables influencing density of each lizard species. Three hundred and fifty three individuals of 14 lizard species were recorded on the sampling plots. Of these species, only one (Acanihodactylus boskianus) was abundant, eight (Plyodactylus gultatus, Stenodactylus sthenodactylus. Mesalina guttulata, M. olivieri, Ophisops elegans, Ablepharus kitaibellii, Chalcides ocellatus, Eumesces schneiderii) were common, and five (Laudukia stellio, Pseudotrapelus sinaitus, Trapelus pallidus, Hemidactylus turcicus, Tropiocolotes steudneri) were rare.

Four main habitat types and two sub-types were distinguished: wadis among loess hills (I); rock outcrops among loess hills (II); rock outcrops among gravel plains (III); wadis among gravel plains (IVa); open gravel plains (IVb), and sand dunes (IVc). Lizard density and biomass were greatest (15-19 ind./ha; about 200 g/ha) in IVb, and IVc, and least (3.7 ind./ha; 38 g/ha) in III. Lizard species richness and diversity were low (three species) in IVc and higher and similar (6-10 species) in all other habitat types.

Among common and abundant species, densities of three (A. boskianus, O. elegans, A. kitaibellii)were highly (30-60% of density dispersion) affected by habitat variables and densities of six (P. guttatus, S. sthenodactylus, M. guttulata, M. olivieri, C. ocellatus, E. schneiderii) were weakly (13-30% of dispersion) affected. Densities of S. sthenodactylus, A. boskianus, and M. guttulata were determined mainly by soil structure, of M. olivieri and O. elegans mainly by structure of annual vegetation, and of C. ocellatus, A. kitaibellii, and E. schneiderii mainly by the structure of shrub vegetation. Density of P. guttatus was determined by both soil and annual vegetation structure.