Short and Long Term Effects of Bioturbation on Soil Erosion and Soil Developmemt in an Arid Rocky Area

Abstract:

Short and long term effects of faunal activity on soil ersion and soil development had been largely overlooked by geomorphologists; especially in rocky arid areas. A study of hiillslope runoff and erosion processes, coducted in the Negev desert, indicated systematic differences in sediment concentration and erosion rates between rocky and colluvial surfaces.. Field observations drew attention to intense burrowing and digging activity of Porcupines and Isopods. Erosion rates were always higher over the rocky than over the colluvial areas. The monitoring of this activity, based on a grid system which consists of rows 5m wide, lasted ten years. Data obtained suggest a link between the spatial pattern of bioturbation and that of soil erosion. The study also examines, through feebback processes , the vregulatory role of bioturbation on soil erosion and soil forming processes. Due to bioturbation two distinct envirobments were recognized.The rocky, upper hilllsope areas, are characterized by a positive feedback process. High runoff and erosion rates remove salt from the soil, preventing thus salt accumulation. At the same time the colluviual slope sections absorb, at most storms, all runoff over the upper rocky slope sectioins leading, over time, tooil salinization