El impacto de la ganadería y la agricultura en los ecosistemas terrestres.-Tras Timanfaya: superpoblación y erosión de suelo en el norte de Lanzarote

Abstract

ABSTRACT The eruption of Timanfaya (1730-1736) has been the most important volcanic activity on Canary Islands during historical times (after XV Century). The lave flows and piroclastic layers buried at least ¼ of Lanzarote’s surface. Overall the island we can see artificial crosssections showing ash layers, overlapping paleargids soils or interbedded between alluvial sediment on the bottom of infilled valleys. Sedimentological analysis has been applied on four cross-section located along the island. These data, together with historical information and pottery remains, allow conclude a very recent age for many of this layers, produced by a strong erosion input started by the overgrazzing produced by the concentration of livestock during the volcanic crisis. All the field and sedimentological data defend an alluvial origin of the acumulation - during historical times in opposite with a peridesertic löess origin in the Lower Holocene defended by other authors.