Some aspects of the regional variation in the amount of available sediment produced by isopods and porcupines, northern negev, israel

A recent study conducted in the Sde Boqer experimental site drew the attention to the possible influence of the burrowing and digging activity of some desert animals on the spatial variation of erosion rates over arid limestone slopes. Such activity provides loose soil aggregates which are easier to remove by shallow overland flows, than is the compacted and crusted loessial soil. In order to study the regional extent of available sediment amounts produced by the biological activity, six plots were selected in the northern Negev in the range of 65 mm to 310 mm average annual rainfall amount. All plots had the same, north facing, aspect and the same lithologic composition. Their size varied from 1110 m² to 5470 m². Available sediment produced was found to vary from 3 g to 70 g/m², increasing with rainfall amount. The distribution of available sediment within each plot was not spatially uniform depending greatly on the spatial distribution of bedrock surfaces and soil cover. The overall possible influence of the biotic activity on short term cycles of soil erosion over limestone arid slopes in the Negev is discussed.