The genesis and development of badlands is controlled by bedrock lithology, topography and climate. The development of badlands in the Central Spanish Pyrenees is favoured by the presence of marls and a climate with a marked seasonality; the combination of these factors results in active hydrosedimentological processes. The aim of the present work was to study the dynamics of badlands in the Central Pyrenees, with a focus on the temporal and spatial patterns of the dominant weathering processes. The study area was a small mountain catchment, and we focussed on the continuous observation of a number of physical parameters that control regolith development and weathering processes. Samples collected from different depths at sites with different aspects enabled temporal comparisons of the factors involved in the development of surface regolith that can be considered as indicators of the weathering of the marls. These indicators were then related to environmental variables (moisture and temperature). Atterberg limits were established and related to moisture content to explain slope dynamics and related processes. Finally, analyses of carbonate content were performed in the laboratory. The results validate the employed methodology, supporting our description of weathering processes, the established chronological sequence and the relation of these processes to climatic and topographic parameters. The results obtained since January 2004 show that the chosen indicators are sensitive to seasonal dynamics, variations in temperature and water supply, and slope aspect. The development and dynamics of regolith on north-facing slopes is more active than that on south-facing slopes. Freezethaw is the main weathering process on north-facing slopes, while south-facing slopes are dominated by the development of crusts associated with wetting-drying processes. Washing effects and lower temperatures upon north-facing slopes mean that the dissolution of carbonates is more pronounced in such areas compared with south-facing slopes, especially within the upper layers of the regolith. favoured by lithology, topography and a climate that is characterized by strong seasonal contrasts in temperature and rainfall distribution. Badlands are characterized by features such as the absence of vegetation, steep slopes and a highdensity drainage network, and hence tend to be among the most significant areas of erosion in the world. This fact is demonstrated by high concentrations of sediment in such areas, as in the Spanish Pyrenees (Valero-Garcés et al., 1999;Beguería, 2005) and the French Alps ('Terres noires'), which can exceed 1000 g l −1 (Descroix and Mathys, 2003). Badlands developed in sub-humid mountain areas are subjected to higher rates of denudation and more active dynamics compared with similar landscapes in arid or semiarid areas (Gallart et al., 2001;Regüés and Gallart, 2004). Rapid and deep weathering (Schumm, 1956), together with intense soil erosion, explain the occurrence of very high erosion rates in badland areas; in some cases...

An exceptional rainfall and hydrological event occurred on 19-21 October 2012 in the central western Pyrenees and was particularly significant in the Upper Aragón River basin and its tributaries, mainly the Irati River. Analysis of historical records showed that, considered separately, the event of 19 and 20 October ranked between the second and fifth highest most extreme daily precipitation events. For the two days combined (with a total between 200 and 260 mm), the precipitation event was the most extreme 2-day event among all observation stations but one. The consequent flood destroyed part of an urban area, and a long stretch of a national road triggered landslides, enlarged the alluvial plain and caused generalised soil erosion in cultivated fields cropped with winter cereals. Badlands in the marls of the Inner Depression yielded high volumes of sediment. The floods in the tributaries were relatively moderate (return periods of 14-42 years), whereas in the Upper Aragón River, the flood corresponded to a return period of approximately 400-500 years and to 142 years at the end of the Yesa reservoir, although difficulties in estimating the discharge increased the uncertainty of these values. The Yesa and Itoiz reservoirs considerably reduced the intensity of the flood in the middle and lower Aragón River and confirmed the importance of the water level in the reservoirs when such rainfall events occur. The water storage in the Yesa reservoir increased from 16% to 53% as a consequence of the event. More integrated studies are necessary to decrease the risks associated with flood hazards. This is particularly the case in mountain areas, where the steep slopes and longitudinal gradients of the rivers shorten the concentration time of floods and increase the energy that erodes channels and riverbanks.

Runoff connectivity depends on topography, rainfall, man-made elements (terraces, trails, roads and drainage systems) and vegetation. In this study, we quantified the effects of 70 years of human activities on runoff connectivity in the mountainous Araguás afforested sub-catchment (17·2 ha; Central Spanish Pyrenees). The IC index of hydrological connectivity was chosen to perform this metric over six land use scenarios at high spatial resolution (1 × 1 m of cell size). The current scenario (year 2012) was simulated with three flow accumulation algorithms (MD, MD8 and D8). MD8 was linked with the most frequent hydrological response of the sub-catchment (rainfall intensity and stream flow during 7 years) and generated the most representative pattern of connectivity, especially in the linear landscape elements (LLE). This algorithm was chosen to simulate five past scenarios (1945, 1956, 1973, 1980 and 2006). In all scenarios, the highest connectivity appeared related to trails and roads, as well as to streams and gullies, whereas the lowest appeared related to stonewalls in 1945 and 1956 to hillslopes in 1973, and the following afforestation. Changes in connectivity mainly depended on the changes in the vegetation factor and in a minor way in the total length, spatial location and type of LLE. Afforestation promoted lower and more stable connectivity at both local and catchment scales.

In this study, we investigated rainfall, run-off, and sediment transport dynamics (414 runoff events and 231 events with sediment information) of a humid mountain badland area -the Araguás catchment (Central Pyrenees, Spain)-from October 2005 to September 2016. Use of this long-term database allows characterization of the hydrological response, which consist of low-magnitude/high-frequency events and high-magnitude/ low-frequency events, and identification of seasonal dynamics and rainfall-run-off thresholds. Our results indicate that the Araguás catchment, similarly to other humid badlands, had high hydrological responsiveness (mean annual run-off coefficient: 0.52), a non-linear relationship of rainfall with run-off (common in Mediterranean environments), and seasonal hydrological and sedimentological dynamics. We created and validated a multivariate regression model to characterize the hydrological variables (stormflow and peak discharge) and sedimentological variables (mean and maximum suspended sediment concentrations and total suspended sediment load). In summer and at the beginning of autumn, the response was mainly related to rainfall intensity, suggesting a predomination of Hortonian flows. In contrast, in spring and winter, the responses were mainly related to the antecedent conditions (previous rainfall and baseflow), suggesting the occurrence of saturated excess flow processes, and the contribution of neighbouring vegetated areas. The multivariate analysis also showed that total sediment load is better predicted by a multivariate regression model that integrates preevent, rainfall, and run-off variables. In general, our models provided more accurate predictions of small-magnitude/high-frequency events than high-magnitude/low-frequency events. This study highlights the high inter-and intra-annual variability response in humid badland areas and that long-term records are needed to reduce the uncertainty of hydrological and sedimentological responses in Mediterranean badland areas.

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The European Mediterranean highlands have undergone a sharp economic decline from the mid-20 th century, causing heavy environmental impacts and loss of ecosystem services. These mountain areas have limited opportunities to integrate into in the current financial system, which demands high productivity from workers and a very competitive product. Extensive livestock farming is one of the few activities able to survive in this context, as it needs little labour and can make use of poor grazing resources. In the north-west Iberian Range, northern Spain, the Leza valley (La Rioja) is showing a growing interest in developing extensive livestock farming. To this end, the regional Government is implementing a pasture regeneration plan for clearing shrubland. Since 1986, almost 30% of the shrubs have been cleared, mainly abandoned fields recolonized by Genista scorpius on lime substrate, and Cistus laurifolius on siliceous substrate. This has increased the available pasture, as the average production in G. scorpius areas has risen from 4566 Mj ha -1 yr -1 (δ ± 1271) to 10,167.3 Mj ha -1 yr -1 (δ ± 2850.3), and on C. laurifolius areas from 2435 Mj ha -1 yr -1 (δ ± 492) to 7628.6 Mj ha -1 yr -1 (δ ± 1428.2). The livestock numbers show an upward trend, going from 1833.9 LU in 1972 to 7207.8 LU in 2017, with a simultaneous increase in the size of farms (27.6 LU in 1972 and 115.2 LU in 2017). In addition, new livestock farms established by people from outside the study area (41.7% in 2017). Finally, there is a discussion on the environmental benefits provided by extensive livestock farming. El desbroce de matorrales como estrategia para fomentar la ganadería extensiva en la montaña mediterráneaRESUMEN. La media montaña mediterránea europea sufre un acusado proceso de marginación económica desde mediados del siglo XX con importantes impactos ambientales y pérdida de servicios ecosistémicos. Estas áreas de montaña tienen escasas posibilidades para integrarse en el sistema económico actual, que exige elevada productividad del trabajador y alta competitividad del producto. Lasanta et al. 488 Cuadernos de Investigación Geográfica 45 (2), 2019, pp. 487-513Entre las pocas actividades capaces de sobrevivir se incluye la ganadería extensiva, que necesita escasa mano de obra y es capaz de aprovechar recursos pastorales de escaso valor. En el valle del Leza (La Rioja, Sistema Ibérico noroccidental, norte de España) existe un creciente interés por el desarrollo de la ganadería extensiva. Para ello, el Gobierno regional desarrolla un plan de regeneración de pastizales a partir del desbroce de matorrales. Desde 1986 se ha desbrozado casi el 30% de la superficie de matorral, fundamentalmente campos abandonados recolonizados por aliagares (Genista scorpius) en sustratos calizos y jarales (Cistus laurifolius) en sustratos silíceos. Con ello se incrementa la oferta pastoral, ya que la producción media en los aliagares pasa de 4566 Mj ha -1 año -1 (δ ± 1271) a 10.167,3 Mj ha -1 año -1 (δ ± 2850,3) y en los jarales de 2435 Mj ha -1 año -1 (δ...

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