Erosión y desertificación.-Contenido en carbono orgánico como indicador del proceso de desertificación en suelos desarrollados de material parental volcánico en la Región de Murcia

Abstract

RESUMEN Soil Organic Carbon (SOC) is an essential component of the global carbon cycle, especially in soils developed from volcanic rocks, due to these soils does not have inorganic carbon. In arid and semiarid areas mineralization of organic carbon is very intense due to climatic conditions, causing soils depletion and therefore desertification. The objective of this study is to determine the content of OC, as a first step in the assessment of desertification processes affecting this area of the southeast of Spain. In this study we selected 14 volcanic outcrops where 10-14 samples were taken and total organic carbon content determined. In some of them, samples from sedimentary parent material were taken for comparing the SOC contents. The results indicated that most of the outcrops show percentages of organic carbon moderately high; this is because of high plant colonization in this outcrop generating a significant content of SOC. Soils developed on volcanic rock showed percentages of SOC higher than the adjacent soils developed on sedimentary material. This could be due to several factors, firstly, the vegetation that colonizes volcanic soil is higher than in sedimentary soils; secondly, the erosion of the sedimentary material produce a loss of topsoil and therefore a decrease in organic carbon content. A third factor could be the stabilizing action exerted by the amorphous materials released during alteration of volcanic rocks.