Macroscale perspectives on the past, present, and potential future of the European megafauna and its ecological impacts

During the late-Quaternary period, human activities have reshaped ecological processes at an unprecedented pace. Human alterations to the climate, biogeochemical cycles, and biodiversity have become increasingly relevant in the last millennia, with large portions of land cleared for farming or timbering and pollution resulting from industrial production and commerce. As the result of increasing demand in a world with developing economies, technological innovation and welfare have generated a loop with these processes spreading worldwide, with an impact magnitude potentially leading to a new geological era, the Anthropocene, dominated by uncontrolled demographic growth and the exploitation of natural resources. Modern human society developed alongside the collapse of megafauna, which are large and diverse species that play a vital role in structuring ecosystems and sustaining complex trophic networks, supporting the life of many other taxa. The decline of megafauna has resulted in functional impoverishment of ecosystems and potential threats such as climate instability, soil impoverishment, and species extinction with unpredictable long-term consequences. As humanity becomes increasingly aware of the challenges posed by the loss of megafauna, the demand for bold strategies of megafauna rebounding is growing. By examining the historical interactions between humans and megafauna during the development of modern society, practical strategies for reintroducing these animals can be formulated to restore ecosystem functionality in areas dominated by human activities. With this in mind, the aim of this thesis was to investigate questions such as the magnitude of ecosystem functions loss resulting from megafauna decline in Europe, the factors that regulate the availability of space for megafauna, and the feasibility of ambitious restoration strategies that balance ecosystem renewal with human-wildlife coexistence targets.