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 sy stems, 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-durat ion 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 respo nse of annual plants was assessed by determining ground cover, height, spec ies richness and diversity, and soil penetrable depth, organic matter and m oisture 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, mot orcycle passage had an immediate significant impact on annual plants at all traffic intensities. The maximum effect on plants was observed in the whee l tracks and in the turn lanes. The mean annual ground cover and height wer e less sensitive measures than species richness and diversity for determini ng the overall impact of motorcycles on the area. Impact of pedestrian and motorcycle traffic on soil was detected only as an increase in penetrable d epth, which was significant at 300 and 500 pedestrian passes, and at 100, 2 00 straight and 150 turn motorcycle passes. The soil and herbaceous vegetat ion of Mediterranean stabilized coastal dunes is relatively resistant and s hows recovery potential to recreational impacts.