Spanish mountains have been affected by the expansion of shrubs and forests since the mid‐20th century. This secondary succession in vegetation has some positive effects, but also drawbacks, such as an increase in fire risk, loss of diversity in land use, a reduction in landscape and cultural value, less water available in river channels and reservoirs, constraints on livestock farming, a reduced number of local species and loss of biodiversity. This paper analyses the potential for grazing domestic goats to help control the spread of several species of shrubs such as the common broom (Cytisus scoparius), red raspberry (Rubus idaeus) and roses (Rosa sp.) that are commonly found in degraded pastures in the Cantabrian Mountains of northern Spain. Using experimental plots, the effects of two levels of stocking density (4·5 and 9 goats ha−1 y−1) are compared with other land management systems used in the region: burning, mechanical clearing and trimming. The combined use of goats with support from burning, clearing and trimming controls the spread of shrubs. The most efficient treatment was found with nine goats ha−1 y−1. Goat grazing also changes the distribution of shrubs, transforming a dense and continuous coverage into separate clumps and thereby enabling livestock to graze more easily. Maintaining a mixed structure of shrubs and pastures is the best treatment due to the low population density of the Cantabrian Mountains, as this enhances the biodiversity, controls fire risk and enriches the landscape; it also allows extensive livestock grazing as a main economic resource. Copyright © 2013 John Wiley & Sons, Ltd.

A total of 206 glacial cirques have been identified in the high valleys of the Aragón and Gállego rivers, Central Spanish Pyrenees, in order to study the environmental factors explaining their distribution (altitude, aspect, lithology) and diverse morphometric features (area, width, length, L/W relations, etc.). The use of bivariate and multivariate statistical analyses confirms that a part of the morphometric variability of the glacial cirques is explained by the environmental factors considered here, but their influence is relatively limited. Altitude is identified as the most important factor, affecting both the length and the degree of over-deepening of the cirques. The role of lithology is less obvious because of its interaction with altitude.

On the evening of the 7 August 1996 an intense storm occurred over the Ara s catchment near Biescas in the central Pyrenees. Eighty-seven people were killed as a result of the subsequent¯ood, which hit a campsite located on the alluvial fan at the outlet of the 18 . 8 km 2 catchment. This paper presents the main results of a hydromorphological study of the event. The Bete s subcatchment received the most intense rainfall, estimated at somewhat in excess of 250 mm, which resulted in a peak¯ow from this tributary of 300 m 3 s À1 . Just downstream from the Bete s river junction,¯ow in the main channel reached 400 m 3 s À1 , increasing to around 500 m 3 s À1 further downstream. Rainfall in the larger Aso tributary was less intense, and in the head reaches¯ow remained within-bank, representing a one in two-year return period event.Flow from this tributary did not exceed 100 m 3 s À1 , indicating that the Bete s subcatchment supplied some 75% of thē ow from just 28 . 7% of the catchment area. The extreme¯ows caused the collapse of a series of sediment trap dams in the Ara s channel downstream of the Bete s junction. This resulted in the addition of 68 000 m 3 of sediment to an already disastrous event. Data from other rain gauges in the area showed both the extremely local nature of the event, and the problems of return period analysis for such storms, whose peaks are rarely observed at gauges. Together with the high geomorphological risks of the zone, this leads to the conclusion that a new method of spatial and temporal risk analysis is required for infrastructure planning.

Until the middle of the 20th Century, Pyrenean rivers were characterized by braided channels, unstable sedimentary structures and an almost complete lack of plant cover in the alluvial plain, due to the high sediment yield in hillslopes and the occurrence of frequent and intense flooding. This was probably related to strong demographic pressures, including the cultivation of steep slopes, frequent fires, deforestation and overgrazing. Depopulation and farmland abandonment resulted in plant recolonization in formerly cultivated areas, causing a decrease in runoff and sediment yield. As a consequence, most Pyrenean rivers tend to reduce the width of the alluvial plain and to replace the braided pattern with an incised, somewhat meandering pattern, involving the construction of new terrace levels and the stabilization of fluvial bars.

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