Geo-ecological soil features and the vegetation pattern in an arid dune area in the Northern Negev, Israel

Soils are suggested to be an important factor influencing the vegetation pattern. In order to prove this hypothesis in an arid and sandy Negev ecosystem of longitudinal dunes and interdune corridors near Israel, the distribution of soil units and plant communities were compared on a very small-distance level. The Nizzana site has a size of nearly 100 ha. 250 soil pits with 3-5 horizons were mapped and sampled within the soil geographical monitoring. Soil water capacity and cation exchange capacity were estimated from the field data. In addition 176 plots of 100 m(2) were established around the soil pits with emphasis on plants, covering the environmental gradient across the dune ridges. Plant mapping plots mere arranged into groups with the same dominating perennial species and a key for the vegetation mapping was developed. In the investigated desert site topography, soil surface cist, soil texture and salt content partly can explain the distribution of plant communities. A soil classification proposal is based on these parameters and isa useful tool to indicate correlations between soil units and the vegetation pattern. Nevertheless, dependent on topography and surface and/or subsurface water flow as well as the occurrence of "fertile islands" the moisture and nutrient regimes influence the vegetation pattern with respect to plant growth to a greater extent than the soils themselves.