Assessment of soil degradation in the Canary Islands (Spain)

Abstract

In the Canary Islands a number of factors, both natural and induced by human activity, act on the fragile ecosystems and agricultural land to cause increasing problems with desertification and progressive degradation of soil productivity. The results of an assessment of soil degradation in the Canary Islands, the processes, causes and impacts, are presented in this paper. Although several processes and factors contribute to soil degradation in the Canary Islands, two have been found to exert a greater qualitative influence: (a) accelerated erosion (water and aeolian); (b) salinization-sodification (natural and induced by agricultural use).Approximately 40 per cent of the Canary Islands' land is undergoing rapid erosion. The factors involved may be grouped into: natural erosion-torrential rainfall, sparse vegetation, high soil erodibility, rugged relief; and erosion due to human activities-unsuitable management of arable soils on the steep slopes, overgrazing and deforestation. About 60 per cent of the surface of the archipelago, including areas given over to intensive agriculture, is affected by salinization. The main factors responsible are: natural-an arid climate and a regime of oceanic winds; and human activitiesoverexploitation of the aquifers, irrigation with water having a high salt and/or sodium content, intensive monoculture, and excessive and indiscriminate use of chemical fertilizers and other agrochemicals.

Soil Salinity and Sodicity in Drylands: A Review of Causes, Effects, Monitoring, and Restoration Measures

“…Another natural source of soil salinity and sodicity in arid and semi-arid regions is linked to volcanic activity, and specifically, to wind-blown ashes rich in sodium-rich minerals such as plagioclases and Na-pyroxenes (Rodríguez-Rodríguez et al, 1993). Secondary volcanic activities, like fumaroles and thermal springs, are sources of chlorine and sulfur components that increase the salinity of groundwater and soils (Di Liberto et al, 2002).…”

Evidence of historic infilling of valleys in Lanzarote after the Timanfaya eruption (ad 1730–1736, Canary Islands, Spain)

“…At the end of the last century, the Department of Soil Science of Universidad de La Laguna (ULL) began studying soil characterization on the eastern Canary Islands, including the processes of degradation (soil erosion and salinization), resulting in several publications (Fernández-Caldas et al, 1987; Hernández et al, 1991; Rodríguez and Arbelo, 2009; Rodríguez et al, 1993, 1998, 2006; Tejedor et al, 1995). However, soil degradation, a serious environmental problem in the arid lands of Canary Islands, has not only occurred during recent times.…”

Tendencias poblacionales recientes de la avutarda hubara en las Islas Canarias: análisis metodológico y estado de conservación

“…ej., unas 125.000 y 36.400 cabras respectivamente en 2010; Gobierno de Canarias http://www.gobcan.es/agricultura/). El sobrepastoreo por cabras ha sido identificado como un problema de conservación preocupante en Canarias, debido a que erosiona el suelo, reduciendo la biomasa vegetal, la disponibilidad de alimento para muchas especies y la biodiversidad animal (Rodríguez et al, 1993;Rodríguez et al, 2000;Martín & Lorenzo, 2001;Gangoso et al, 2006). Además, hay evidencias de que una elevada densidad de ganado tiene un efecto negativo sobre la hubara debido a molestias y disminución del éxito reproductivo (Lavee, 1988;ver también Pavel, 2004 para su generalizado efecto sobre otras especies), de manera que se ha detectado en la hubara una clara evitación de las áreas con mayor carga ganadera de cabras y ovejas (Le Cuziat et al, 2005b).…”