Habitat fragmentation and species interactions
Forest edge habitats, resulting from habitat fragmentation, often expose the organisms inhabiting them to a set of environmental conditions in the surrounding matrix that are different from the natural environment in the forest interior, less disturbed, habitats. These new environmental conditions may affect the ecology of some species, such that variations in ecological processes, including species interactions and the outcomes of such interactions may be observed along a gradient of forest edge to interior habitat. In a previous research, for instance, Razafindratsima et al (2018) showed that forest edge creation, as a result of habitat fragmentation, poses a threat to the phylogenetic and functional diversity of highly diverse tree communities.
We are interested in exploring how habitat fragmentation influence plant-frugivore interaction networks, by comparing the structure and strength of these networks in edge vs. interior habitats. We also aim to investigate how changes in frugivore community from a gradient of forest-edge to interior habitat influence the rates of seed dispersal and seedling recruitment dynamics.
PhD student associate Nancia Raoelinjanakolona has recently been awarded a Rufford Small Grant and a National Geographic Society Early-Career grant to conduct some of the objectives related to this topic in the rainforest of Ihofa as part of her PhD at the University of Antananarivo.
Biological invasions impacts on ecological communities
Biological invasions of native communities by exotic species are among the top ecological problems the world is facing today. In forest ecosystems, invasion of introduced plant species can pose serious threats to biodiversity and ecosystem function. Thus, understanding the mechanisms that facilitate their spread and their impacts at the community-level can provide important insights for control and management.
In Madagascar's rainforests, one of the major conservation concern is the highly invasive strawberry guava (Psidium cattleianum). In a recent collaborative research, we found that its invasion decreases the taxonomic and functional diversity of Madagascar's rainforests (DeSisto et al. 2020). Further, at a local scale, its presence was associated with an increase in frugivore species richness. It has indeed become a major food source for many endangered lemur species. The findings highlight the complexity of invasive species management as this species is important for both native fauna and human communities who commonly use it for food, medicinal purposes and construction materials. We are thus working on unraveling these complex interactions to provide tools for forest managers for an holistic approach to address the management of this species.