A historical ecological assessment of arid aeolian sedimentary systems responses to long-term land uses in the Canary Islands

Resumen

In recent decades, coastal areas have been under significant human pressure due to the increasing process of littoralization that is taking place. However, many of these areas, such as the arid aeolian sedimentary systems, behaved as socio-ecological systems even before the arrival of tourism, that is to say, the influence of human activities has determined its natural dynamics for centuries. In this context, the general aim of this thesis is to analyse the anthropogenic alteration of the coastal arid aeolian sedimentary systems of the Canary Islands, and to determine, their environmental consequences in the natural dynamics. It is also intended to analyse the natural responses of these ecosystems to human alterations and the social relevance of such changes. The main results of this doctoral thesis show that traditional land uses (exploitation of vegetation for use as fuel, grazing, cultivation, etc.) produced important changes on vegetation, aeolian landforms and, therefore, in the natural aeolian sedimentary dynamics. These changes are still visible and determine the landscape on which the tourism industry is based, which has become the main activity of these ecosystems. These changes have also severely affected the populations that depended on them for their subsistence. The alteration of the historical provision of ecosystem services produced by land uses caused the population to change and adapt management measures to guarantee the productivity of these services by the ecosystem. However, other important results of this doctoral thesis are related to the response capacity of ecosystems to historical alterations. It has been observed that these systems do not return to the conditions prior to human disturbances; on the contrary, they adapt and reorganize based on different factors such as the volume of available sediment, topography or the capacity of the vegetation to colonize the areas transformed by historical and current land uses. Finally, the results obtained in this doctoral thesis can serve as a tool to improve the management of not only the analysed beach-dune systems but also similar systems in other parts of the world.