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A dune area of 2 km' in the Negev (Israel) with an annual precipitation of 90 mm was mapped. The soils developed from eolic and fluviatile sediments were Arenosols. Calcisols. Solonchaks. Regosols and Fluvisols. The Arenosols of the dunes are more homogeneous in texture and salt content than the soils ofthe interdunal corridors: Besides the Fluvisols, also the Calcisols, Solonchaks and Regosols are stratified due to episodic flooding by a wadi, and are rich in salts and lime.The soils are of minor development. Aggregalion and enrichment of lime, enrichment and movement of salts. and the enrichment of organic substances are indications of soil formation.The distribution of salts within the profiles was calculated by their solubility. High and low soluble salts appear together in thin layers of Calcisols, Solonchaks and Fluvisols, while the most-soluble salts appear in deeper layers. The salts, therefore, must have accumulated by lateral movement, precipitation and temporal flooding. Influence of groundwater can therefore be excluded. The Arenosols also show the same sequence of salt types. indicating the accumulation due to precipitation and eolic mass movement. Abandoned arable land sites did not show any different soil characteristics from the unused soils.On the basis of the distribution of salts in the profiles and soil types genesis and classification of the soils is discussed.

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 Nizzaoa. 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 I00 ha. 230 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* were established around the soil pits with emphasis on plants, covering the environmental gradient across the dune ridges. Plant mapping plots were 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 C N S~, soil texture and salt content partly can explain the distribution of plant communities. A soil classification proposal is based on these parameters and is a 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.

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