Since the work of the USDA in the 1940s, it has been widely accepted that vegetation cover is a key control on the rate of overland flow runoff and soil erosion relative to rates on bare soil. This was confirmed empirically in South Africa, experimentally at Purdue and digitally by Kirkby and Neale. In fact it has become commonplace to attribute catastrophic erosion almost universally to vegetation removal. Conversely re-vegetation, and in particular afforestation has been seen as a universal solution to Land Degradation. Because agricultural crops commonly leave the ground poorly protected during critical rainfall periods, Silsoe College developed an inventory of the crops most suitable for good conservation practice. The â€˜Ruinationâ€™ of the Mediterranean has been widely attributed to â€˜overgrazingâ€™, often many centuries old, although this hypothesis has recently been questioned by Rackham and Grove and the whole dynamic of grazing and erosion has been investigated by Thornes. New models are now emerging to simulate the dynamics of grazing behaviour and its impact on erosion.
The time is now ripe for a major review of these issues in the light of fresh experimental, practical, theoretical and historical work.. Contributions are invited in all these fields to improve our theoretical and empirical understanding of the spatial and temporal relationships between vegetation, runoff and erosion, particularly but not exclusively for semi-arid areas including the Mediterranean.
Publication. We should seek a revised version of Vegetation and Erosion from Wiley to To be edited in honour of John Thornes.
This text was written down by Professor John Thornes May 2nd 2008 and submitted to the SSS Division of the EGU
David Dunkerley. Monash University. Victoria. Australia
David Montgomery. USA
José Carlos González Hidalgo. Universidad de Zaragoza. Spain