On the contribution of air-borne salt to the gradient character of the Voorne Dune area

The distribution of air-borne salt in a distinctly zonated coastal dune area has been investigated by means of 27 simple measuring instruments, placed in 4 transects, perpendicular to the coastline: two in a northwest-southeastern line, the other two in a southwest-northeastern line. The pattern of distribution proved to be determined by wind velocity, distance from the sea, wind direction, height above N.A.P. and shelter by surrounding vegetation. Most salt was deposited during high wind velocities. The influence of rainfall was difficult to establish because periods of high rainfall usually coincide with those of high winds. It is stressed that the income of nutrient elements from sea-spray is only half of the significance of air-borne salt as a contributor to the gradient system of the dune environment. For the existence of gradients in space and time and thus for biological diversity the leaching by rain and any other decrease of these elements is just as essential.