My research interests span community ecology, functional ecology, and evolutionary ecology. I am interested in understanding how biological communities assemble in space and time, shaping biodiversity across different scales and influencing ecosystem functioning. My research combines a theoretical approach of community ecology and functional strategies with a quantitative empirical approach based on field observations and experiments. A plant ecologist at the core, most of my research is on vascular plants. However, I have started expanding my research to different interaction partners, lately working on plant-herbivore interactions. I have been working in a range of systems, from native forests to urban grasslands, with a specific focus on semi-natural rangelands.
Impact of alien plants on plant community structure
I have been working with Phil Hulme on assessing the impact of alien plants on plant community structure. Invasive aliens are expected to have a major impact on the resident community, e.g. by competing for resources with natives or modifying the environment. However, while reductions in species richness have been widely reported in invaded sites, the impact of invasive species on other aspects of community structure (e.g. functional richness, phylogenetic diversity) are rarely quantified. Moreover, although the impact of an invasive species is often expected to increase with invader abundance, impact studies tend to remain limited to contrasting invaded vs. non invaded sites, and only rarely explore gradients of invader abundance.
We have been investigating how community structure (e.g. species richness, functional and phylogenetic diversity) varies along gradients of invasions for over a hundred widespread exotic species across Banks Peninsula, in the South Island of New Zealand. Using null models and results from species distribution models, we quantified the significance and the size of the impact of these alien species in this landscape.
Plant community assembly along environmental gradients
My PhD project focused on understanding plant community assembly in dry calcareous rangelands of Southern France, situated on the Larzac Plateau. To do this, I studied how these herbaceous plant communities are structured along a natural gradient in soil resource. I used an integrative approach combining functional, phenological and phylogenetic characterizations of plant diversity both within (alpha scale) and among (beta scale) communities to try to detect the complex processes shaping community assembly in these rangelands. My main goal was to try to go further towards a general understanding of plant community assembly by testing, refining and contradicting a number of widespread hypotheses in community ecology.
Plant trait evolution
I am also interested in trait evolution and trait phylogenetic conservatism and diversification. I have investigated the phylogenetic signal of nine vegetative, reproductive and phenological plant traits across herbaceous species from the South of France (Bernard-Verdier et al. 2013, JVS). I am also currently working with Olivier Flores (Université de la réunion – CIRAD) and Eric Garnier (CEFE, Montpellier) on a larger project comparing the phylogenetic signal of different leaf traits using a global trait database covering thousands of vascular plant species.
Functional diversity and ecosystem functioning
Another aspect of my graduate research was to study the relationship between functional diversity and ecosystem functioning in Mediterranean rangelands of Southern France. Water limitations being the main constraint in this region, I focused on water-balance and productivity, investigating how these ecosystem functions may be related to community functional structure. More specifically, I tested whether a higher diversity of resource-use strategies coexisting in a local community was associated to a higher water-use efficiency at the community level. I explored the relationship between trait diversity and water exchanges at the community level for a number of plant functional traits, both in a mesocosm experiment and in the field (in collaboration with Karim Barkaoui).