Effect of experimental trampling and off-road motorcycle traffic on soil and vegetation of stabilized coastal dunes, Israel

Coastal sand dunes are considered to be amongst the most fragile natural systems, however they may be subject to high-intensity recreational stresses. The aim of this study was to assess the response of soil and annual plants of stabilized Mediterranean coastal dunes in Israel to various short-duration pedestrian and motorcycle traffic intensities. A standard experimental procedure was used comprising of 0, 50, 100, 300 and 500 pedestrian passes, and 0, 20, 50, 100, 200 straight and 150 turn motorcycle passes. The response of annual plants was assessed by determining ground cover, height, species richness and diversity, and soil penetrable depth, organic matter and moisture content. The pedestrian traffic did not affect the cover of annual plants, however; mean annual height, species richness and species diversity were significantly but temporarily affected by 500 passes. Conversely, motorcycle passage had an immediate significant impact on annual plants at ail traffic intensities. The maximum effect on plants was observed in the wheel tracks and in the turn lanes. The mean annual ground cover and height were less sensitive measures than species richness and diversity far determining the overall impact of motorcycles on the area. Impact of pedestrian and motorcycle traffic bn soil was detected only as an increase in penetrable depth, which was significant at 300 and 500 pedestrian passes, and at 100, 200 straight and 150 turn motorcycle passes. The soil and herbaceous vegetation of Mediterranean stabilized coastal dunes is relatively resistant and shows recovery potential to recreational impacts.