Soils represent an essential natural, practically non-renewable resource that provides many critical ecosystem services necessary for life. Furthermore, soils play a critical role in maintaining the balance of the carbon cycle, acting as the largest terrestrial carbon pool which made them crucial in mitigating climate change. Understanding the complexity and dynamics of soils is, therefore, apart from preserving and managing this valuable natural resource, critical for the benefit of current and future generations. However, the changing climate and increasing intensity of agricultural production pose significant threats to the sustainability and role of soils, mainly by contributing to a depletion in soil organic matter (SOM) and altering its dynamics. Indeed, Mediterranean soils face these threats in a more severe way due to their geographic location, particular climate and inherent low content of SOM. It is critical to shedding light on this respect by combining different analytical procedures and providing complementary and valuable information on processes that regulate the accumulation, decomposition, and transformation of SOM. The main objective of this thesis was to investigate and deepen our knowledge about the two main threads affecting carbon dynamics in Mediterranean soils i.e., climate change and intensive agricultural practices. For this, advanced analytical techniques appropriate for the study of complex matrices such are soils were tested and combined to study SOM in two distinct and representative Mediterranean soils, in terms of extension and ecosystem relevance: Mediterranean savannahs, commonly known as “dehesas” (Section I) and agricultural soils (Section II).

El presente trabajo se ha realizado en el marco del proyecto titulado “Intercambio y flujos de carbono en suelos de ecosistemas mediterráneos naturales y manejados (bosques, dehesas y cultivos” (INTERCARBON, CGL2016-78937-R), así como en colaboración activa con el proyecto titulado “Las dehesas frente al cambio global: una aproximación multi-funcional (DECAFUN, CGL2015-70123-R)”. Ambos proyectos han sido financiados por el Ministerio de Economía y Competitividad (MINECO), así como el contrato predoctoral de Layla Márquez San Emeterio dentro del proyecto INTERCARBON como parte del Programa Estatal de Promoción del Talento y su Empleabilidad en I+D+I para la formación de doctores (FPI, BES-2017-07968). La Unión Europea ha colaborado con el aporte de fondos de cohesión (FEDER) a los anteriores proyectos y mediante los proyectos MAXRoot-C y MIXRoot-C. European Joint Programme EJP SOIL “Towards climate-smart sustainable management of agricultural soils” 2nd Internal Call topic: CM1 — Plant below-ground inputs to enhance soil carbon sequestration (Grant Agr. Nr. 862695).

Tesis doctoral para optar al grado de Doctora por la Universidad de Sevilla

Peer reviewed