Field experiments on the transport of rock fragments by animal trampling on scree slopes

Qualitative observations in an area with steep scree slopes in Turkey suggested that trampling by goats and sheep may contribute significantly to the downslope movement of rock fragments in these environments. Therefore, a series of field experiments was set up to determine the rate of rock fragment transport caused by trampling. The experimental results allowed the calculation of a unit displacement distance from each trampling experiment, which may then be used to extrapolate the measured transport rates over longer time periods and larger areas. Although such extrapolations should be interpreted with great caution, the results demonstrate that trampling contributes significantly to rock fragment transport in such environments, as calculated yearly displacement distances are equal to, or higher than, those reported in the literature for other geomorphic processes. The observed travel distance distributions are not well described by a negative exponential distribution. Trampling causes a weak downslope sorting (the coarsest clasts move farther) but has a significant effect on vertical sorting and is one of the factors which can explain the layered structure of the scree slopes in the area.