Original paper

Sheep and goat erosion – experimental geomorphology as an approach for the quantification of underestimated processes

Ries, J. B.; Andres, K.; Wirtz, S.; Tumbrink, J.; Wilms, T.; Peter, K.D.; Burczyk, M.; Butzen, V.; Seeger, M.


The grazing of goats and sheep is regarded as an important factor for soil degradation in semiarid landscapes. Nevertheless, hardly any data can be found in literature. In the presented study, the process dynamics of material disaggregation and translocation directly caused by trampling animals was quantified by means of experimental methods on test plots. Gerlach troughs were installed in order to quantify material mobilization in different directions. The slope angle and the running speed of the animals were varied. Additionally, the amount of material that was loosened by the hooves of the goats was measured. The translocation rates were surprisingly high and slope angles as well as running speed turned out to be important influencing factors. In downslope direction, each goat translocated rock fragments from an amount of 0.6 g up to 6.5 g on each square meter, depending on slope. The maximum translocation rate in movement direction reached 4.5 g m–2 per goat for fast running and 1.3 g m–2 per goat for slow motion. Additionally, each goat could loosen 14 g of soil material per square meter; this material could easily be removed by wind or water. Experiments with marked rock fragments on slopes of 4° and 11° showed that a flock of 45 goats translocates rock fragments (∅ 3 cm) by a mean distance of 8.8 cm. While rock movement occurred in all directions, most often the rock fragments were kicked forward downslope. Net mean downslope translocation rates varied between 1.5 cm and 6.6 cm corresponding with slope and the total number of rock fragments moved.


erosionexperimental geomorphologymediterranean landscapessheep and goats