Ecogeomorphological transect approach to evaluate the origin of gullies and badland-shaped morphologies in a high mountain environment: Sierra de las Nieves National Park (South of Spain).

Sierra de las Nieves National Park, located in South of Spain and mainly of built on calcareous rocks, is characterised by Mediterranean mountain climate (exceeding 1,000 mm y^-1 and humid and cold winter) and a long tradition of human activity in previous centuries. The experimental area is located in its upper part close to the highest peak (La Torrecilla, 1,919 m.a.s.l) forming a plateu-like relief between 1,600 and 1,700 m.a.s.l where calcareous hills are separated by valleys of lower slopes filled with marls and quaternary sediments. Vegetation corresponds to an opened-mixed vegetal formation of Quercus Faginea and Abies pinsapo Boiss. with typical high mountain shrubs and meadows. The current land use is natural protected area, though goat and sheep grazing is permitted if the number of cattle is low to reduce fire risk. Before the declaration as protected area, the grazing pressure was major. In addition, the deforestation had a huge impact in last centuries to provide materials for naval industry and charcoal.

Gullies and badland landscapes are commonly found in intra-basin mountainous areas in the Mediterranean region. However, the Sierra de las Nieves National Park (South of Spain) includes these one in high mountains environments over 1,500 m.s.a.l. The main factor to explain this is the existence of soft materials (marls, mainly) interbedded among massive calcareous rock formations. These materials are not very extended, but they are proned to the formation of gullies and badland morphologies when vegetation cover is low. This study aims to provide an approach to the main causes originating these morphologies, either climatological or human activity.

To do this an integrated approach from an ecogeomorphological perspective was applied. One transect was defined in one selected gullied-area including 15-sampling points and ecogeomorphology described: vegetation, soil surface conditions, and current geomorphic processes. In addition, soils were also sampled in depth at the same points and some properties analysed in laboratory: colour, texture, organic carbon, organic matter, pH, electrical conductivity, aggregate stability, and water holding capacity. The transect runs along the maximum slope line from one hill to the valley bottom and continue towards the top of the opposite hill. In the valley bottom, there was a fluvial Quaternary deposit covering and fossilising the marls formation. When outcropped, these marls were affected by concentrate water erosion forming gullies. In addition, its surface developed typical morphologies of Badlands: cracks and crusts in dry conditions, short and shallow mudflows in wet conditions, and popcorn in winter. The samples at 10, 20, 40, and 60 cm of depth taken from the alluvial deposit were dated by means C14 technique giving dates of recent years, 318±49, 1006±49, and 1767±48 before present. The sample from 60 cm depth corresponded to the lower part of the alluvial deposit in contact with the marl formation. Ecogeomorphology inventory, soil properties, and datations have been used to shed light on the age and origin of the formation of gullies and Badlands, but further investigations are required, especially those providing historical changes in vegetation species.