Historical geomorphic processes and human activities in the Central Spanish Pyrenees

In the Central Spanish Pyrenees there is a great diversity of geomorphic processes due to topographic and climatic heterogeneity and altitudinal gradient. Human activity during the last 4,000 years has contributed to the disturbance of the original landscape and its hydro-morphological dynamics. The upper forest belt was destroyed by fire during the Middle Ages in order to provide summer pastures to transhumant livestock. The hillslopes below 1,600 m were cultivated and frequently burnt to improve the soil and pasture quality, even on steep slopes. The most evident consequence of this has been the increase in the sources of sediment. In the subalpine belt, mass movements and dense rill networks have caused severe soil erosion and the expansion of gelifluxion terracettes; in the middle mountain belt overland flow has resulted in stoniness of the soil surface, and debris flows have occurred on hillslopes and along river channels. This paper discusses the effects of human activity on the geomorphic processes in the study area.