CESAM and the Study of Biodiversity in Mediterranean Ecosystems

On the International Day for Biological Diversity, CESAM marks the occasion with an opinion article by João Carvalho, researcher at CESAM/DBIO, on the role of biodiversity and the functionality of Mediterranean ecosystems. The initiative is also accompanied by a small photographic showcase featuring images captured by CESAM researchers within the scope of the projects they are involved in.

While Pliny the Elder and, more recently, Edward O. Wilson suggested that nature reveals itself in the perfection of the smallest beings, John Terborgh reminds us that our vision is often incomplete when we overlook large creatures, including their indirect effects on ecosystems. This dichotomy reinforces the need to consider ecosystems as fully functional networks, where the precision of the micro and the magnitude of the macro are intertwined. It is within this interdependence — this array of sizes, shapes, colours, and functions — that biodiversity and evolution emerge as the greatest spectacle on Earth.

We are truly privileged to inhabit the Mediterranean Region, a biodiversity hotspot “between lands”, shaped not only by the force of geology and the harshness of climate, but also by the millenary influence of human activities. Although the resilience of Mediterranean landscapes and the organisms that inhabit them is remarkable, the impact of our actions is profound and calls for an increased sense of responsibility. Understanding, managing, and protecting biodiversity ultimately means preserving the functional balance of this region.

To achieve this, it is essential to decipher how different variables and pressures directly and indirectly affect biodiversity, shape ecosystem functionality, and impact the integrity of its various compartments, from soil to vegetation. This is where the role of the researcher lies. We work amidst environmental unpredictability, the interdependence of ecosystem compartments, the sensitivity of animal behaviour and, of course, against our own ignorance. On our side, however, are the fascination for the natural world and the power of the scientific method, which allow us to continuously improve our understanding of the world through the exploration of new ideas and hypotheses.

Under this premise, the rWILD-COA project – Ecological challenges and opportunities of the rewilding process in the Côa Valley – is based on the hypothesis that large herbivores have a significant impact on ecological and functional processes, positioning them as protagonists within a network of relationships that determines the dynamics of Mediterranean ecosystems and, consequently, their biodiversity. The rock engravings of the Côa Valley confirm the historical presence and ancestral connection of these animals to the territory. Taking the beautiful Faia Brava reserve as a true living laboratory, the project has shown that, as ecosystem engineers, the activities of these species influence soil functional processes and vegetation structure, contributing to a mosaic of habitats that shapes local biological richness, from small invertebrates to rodents, reptiles, and mesocarnivores. Additionally, large herbivores play an important role in biomass management, contributing to wildfire risk reduction and landscape resilience.

Aligned with CESAM’s thematic line “Socioecological Systems and Resources” (TL3), this project integrates knowledge from the Ecosystem Management and Conservation cluster (RC4) and the Soil Functions, Agriculture and Forests cluster (RC2). By deciphering how large creatures influence — and are influenced by — the diversity and abundance of smaller ones, we transform knowledge into management strategies. This knowledge, grounded in the relational network across different ecosystem levels, contributes decisively to maintaining or restoring the functionality of Mediterranean landscapes.

Article by João Carvalho, researcher at CESAM/DBIO.