A survey of tracks and paths in a sand dune ocosystem. I. Soils. II Vegetation.
Bulk density and soil penetration resistance was linearly related to the log of the number of passages of a car, up to 256 passages, and of walkers, up to 1024 passages. It is concluded that short-term trampling compacts the surface layers of soil and that longer term trampling may compact the soil to a greater depth. A given number of passages by a car increased the soil bulk density by 30% and the penetration resistance by 100% more than did the same number of passages by walkers. The water content of compressed soil in dry areas was greater than the adjacent undisturbed soil; this could aid the survival of plants on tracks and paths. Compaction is likely to induce anaerobic conditions during the winter in wet areas, and increase the build up of organic material. The relative proportion of monocotyledonous species dropped and that of dicotyledonous species rose under moderate trampling levels. However, with increased trampling this relationship was reversed. A greenhouse experiment indicated that while damage to shoots by vehicles was detrimental to plants, soil compaction alone could be beneficial in the sand dune habitat. It is possible that control of the level of wear could be used to create aesthetically pleasing communities and diversify the vegetation in an otherwise undisturbed habitat.