Ecology has a long history of studies on negative interactions, such as predation and competition. Although, numerous studies have highlighted the importance of positive interactions, such as facilitation. The integration of facilitation into modern ecological theory has nonetheless lagged behind. In particular, we had little evidences of the effects of positive interactions on community structure.
Facilitation has been extensively studied in plants. It happens when a plant (called nurse), increase the fitness of another plant (called beneficiary). We can distinguish direct and indirect facilitation. Direct facilitation arises when a nurse improves its surrounding environment by increasing amount of resources such as water and nutrients. Indirect facilitation occurs when there is at least a third species. When a nurse decreases the predation rate of an herbivore on plants, there is an indirect positive link from the nurse toward the beneficiary.
My PhD aimed to explore the effects of plant-plant interactions at the community scale, with a focus on indirect interaction and positive interactions. The main research question was: What are the effects of a nurse plant on the community of beneficiary ?
In the first place, we looked at the effects of different nurse strategies against grazing on the community structure of the beneficiaries (paper on filtering and on dominance and niche differentiation). In the other side, we examined the effects beneficiary community composition on the relationship that they had with the nurse (work still in preparation).