Why most agricultural terraces in steep slopes in semiarid SE Spain remain well preserved since their abandonment 50 years go?

A large part of the agricultural terraces in mountain environments are abandoned, like those from the Filabres range in Almería, SE Spain. While many of such terraces show signs of soil erosion (wall disruptions, surface crusts, pipes and gullies), others in steep slopes remain well preserved after 50 years since their abandonment and still seem to play an active role against soil erosion. In order to know both magnitude of soil erosion and controlling factors in different types of abandoned terraces, a rainfall simulation campaign with a portable sprinkler was carried out in 45 representative microsites. Runoff, derived-infiltration and sediment production were measured and their relationships to basic soil parameters (particle size distribution, pH, EC, organic matter content, aggregate stability), geomorphic position, and ground cover, were examined. Under the average applied rainfall intensity (48 mm/h, which represents a precipitation with a return period of 5 years in the area), narrow bench terraces from steep hillslopes, have larger infiltration values and deliver less sediments than large bank terraces in alluvial plains. The presence of stony pavement sieving crusts on narrow-bench terraces and also on un-terraced alluvial fans, play an essential armouring effect against soil erosion while favouring water infiltration. Considerations are made about the evolution of the different types of traditional terraces in the area under both past agricultural and present abandoned status, and also about possible uses under a sustainable land management policy. Una gran parte de las terrazas agrícolas en zonas de monta a están abandonadas, como las de la Sierra de los Filabres en Almería, SE de Espa a. Si bien muchas de dichas terrazas muestran se ales de erosión hídrica (destrucción de muros, encostramiento superficial, piping y cárcavas), otras en laderas con pendientes acusadas siguen bien conservadas tras 50 a os de abandono y da la impresión de que todavía juegan un papel activo contra la erosión del suelo. Con la finalidad de conocer tanto la magnitud de la erosión como sus factores causantes en distintos tipos de terrazas abandonadas, se llevó a cabo una campa a de simulación de lluvia con un aspersor portátil en 45 sitios representativos de la vertiente Sur de la Sierra de los Filabres. En cada simulación se midió la escorrentía y la producción de sedimentos, se calculó la infiltración y se determinaron las relaciones de dichos parámetros con los del suelo (granulometría, pH, CE, materia orgánica, CaCO3 y estabilidad de los agregados), con su posi