Ecosystem services around the Mediterranean Basin

Soutenance de thèse de Ana Paula GARCIA NIETO, vendredi 14 Décembre 2018 à 10h00

Bâtiment Cerege
Technopôle de l’Arbois-Méditerranée
13545 Aix-en-Provence

Membre du jury

Ariane WALZ   Professeur, University of Potsdam
Marc METZGER Professeur, University of Edînburgh
Virginie BALDY Professeur, Aix-MarseîlleUniversité
Rutger DEWIT Directeur de Recherche, CNRS
Wolfgang CRAMER Directeur de Recherche, CNRS
Directeur de thèse
llse GEIJZENDORFFER  Chargée de recherche,
Co-directrice de thèse
Tour du Valat

Global change, through the impact of human activities on the processes that regulate the functioning of the Earth system, poses important challenges to society. The acceleration of human pressures during the last decades has had profound impacts on Mediterranean socio-ecological systems including the reduction of important contributions from nature to human well-being, referred to as ecosystem services (ES). For the coming decades, there is growing concern about how pressures of social-ecological systems, in particular urbanization, land management practices and nature conservation policies, will affect the supply of ES in the Mediterranean Basin and how the associated vulnerabilities could be reduced. Sustainable supply of ES is a key prerequisite to the achievement of many Sustainable Development Goals (SDGs), but knowledge on how this could best be achieved is sparse, in the Mediterranean Basin but also elsewhere. This lack of knowledge is not confined to issues of scientific understanding, but also to the fact that research efforts are more limited in Northern African countries as compared to Europe. There is a particular need to elucidate trends, trade-offs and synergies between ES under the influence of pressures and management in the wider Mediterranean basin.

The main goal of this thesis is to analyze how ES flows in the Mediterranean Basin area, and the trade-offs between them, are affected by drivers of change. To this end, a multidisciplinary assessment perspective - from biophysical to socio-cultural factors, covering multiple spatial scales from the local to the Mediterranean Basin - has been used to analyze changes in ES supply and demand. The core results are presented on three independent studies. In the first one (chapter 2.1) I assess land cover and ES capacity supply trends in Mediterranean peri-urban areas due to urbanization using spatial open data sources. In the second sub-chapter (2.2), I present a literature review to identify the impact of conservative management practices on ES. In the third subchapter (2.3), I explore the impact of the role of stakeholders in environmental management decisions on their perception of ES patterns using collaborative mapping workshops.

In the peri-urban zones around 12 Mediterranean cities I found a general decrease in the overall capacity to supply ES due to land cover changes (1990 – 2016) (chapter 2.1). In the European peri-urban areas, expansion of the urban surface has occurred at expense of agricultural land loss, whereas in North African experienced an increase of irrigated agricultural land. In chapter 2.2, a selection of alternative management options positively impacts the supply of regulating ES in Mediterranean agro-ecosystems. In contrast, crop yield was increased using management options such as no tillage and mulching, but decreased under mulching among others. Chapter 2.3 demonstrated that the spatial scale of influence of stakeholders on ES management affects the recognition of contributions from specific or wider landscape elements (e.g. protected areas) to ES supply.

The revealed impacts of urbanization and commonly applied agricultural management systems negatively impact the supply of ES which may hinder the progress Mediterranean countries strive for within the frame of the SDGs. Better management of land use systems along the rural-urban gradient and the engagement of stakeholders could help to assure progress towards the SDGs. The chosen methods and data affect the results with regards to ES trends, synergies and trade-offs detected. In this thesis I recognize the need to apply integrated ES assessment to provide the estimation of trends, and the existence of shared knowledge within stakeholder groups that can provide the much needed link between theory and practice. This thesis evidence that the inclusion of diverse dimensions of the social-ecological systems can improve the understanding of ES flows and changes therein.