Combined effects of deforestation and biodiversity loss on species coexistence and ecosystem functioning
Human activities are profoundly impacting life on Earth and increasingly threatening the functioning of ecosystems, with severe consequences for human well-being. In particular, recent experimental studies have shown that deforestation and biodiversity loss are disrupting key ecosystem functions on which we rely. Yet, we have a limited understanding of the mechanisms underlying the impact of these major anthropogenic perturbations on the functioning of ecosystems. Modern coexistence theory highlights mechanisms of species interactions responsible for biodiversity maintenance, including niche differences and fitness differences. This project aims at disentangling the consequences of deforestation and biodiversity loss for species coexistence, and the role of coexistence mechanisms in mediating ecosystem functioning of forest communities. I plan to establish a new deforestation x biodiversity experiment using the herb layer of Mediterranean and tropical forests as a model system. The experimental design includes plant communities with different levels of species richness in the herb layer. I will manipulate plant species richness by sowing seeds from a pool of four plant species using native herbs in forested and deforested ecosystems in Mediterranean and Tropical climates. First, I will test the consequences of deforestation and biodiversity loss of herbs for species coexistence using state-of-the-art ecological models. Second, I will examine the role of coexistence mechanisms in mediating the effects of deforestation and biodiversity loss on ecosystem functioning, such as biomass productivity and reproductive potential of herbs. Evidence of these hypothesised synergistic effects of deforestation and biodiversity loss on species coexistence and of the role of coexistence mechanisms in mediating ecosystem functioning would be the first in ecological literature. Addressing these questions will fill a key knowledge gap in understanding the impact of human activities on ecosystem functioning via their effects on species coexistence.