Erosión y desertificación.-Biophysical- and socioeconomic aspects of land degradation in the Guadalentin (SE-Spain): towards understanding and effective soil conservation

Abstract

ABSTRACT Desertification and land degradation have been widely studied in the Guadalentin basin (SE Spain) through various national and international research projects. Most important identified degradation types are due to soil erosion, soil surface crusting, aridity, soil organic matter decline and salinisation. On the one hand, political and socioeconomic drivers have caused important land use and management changes, which have formed an important driver for further land degradation. On the other hand, soil conservation practices were initiated by the government and by individual land users, although there is very limited knowledge on their effectiveness. The objective of this work is to provide an overview of previous studies that addressed land degradation in the Guadalentin and to present an integrated synthesis of the main biophysical- and socioeconomic factors identified in these studies as being responsible for land degradation, with a focus on feasible soil conservation strategies. In overall, there has been strong emphasis on the study of biophysical characteristics related to climate, vegetation, soil, flooding, hydrology, and partially on the socioeconomic and political drivers of land degradation. The latter especially focussed on the effects of agricultural subsidies on land use changes and land degradation. Most studies have concentrated on the headwaters of the Guadalentin and on areas with (semi-) natural vegetation. Important examples of issues that remain under-researched are: 1) costs of land degradation (on-site and off-site), 2) effects of different conservation strategies on the short- and long-term, on-site and off-site, 3) the effect of large-scale land conversion by land levelling and urban expansion, and 4) the future implications of land managers’ decisions on land degradation.