Calibrating the link between demography and functional traits

Functional traits are easy to gather and are increasingly being available in open databases. Thus, they potentially constitute a great source of information about species demography (growth rate, carrying capacities, pairwise interaction coefficients etc…) and could potentially be used to improve community models. However the link between demography and functional traits is not clear.
As a post-doctoral researcher in the Laughlin lab, I am currently improving the Traitspace model by incorporating a flexible formulation of biotic interactions among species to improve local species abundance predictions.  I am further analyzing experimental datasets to access the influence of functional traits on plant growth in various environmental conditions.

Main collaborators: Florian Hartig, Daniel Laughlin, Loïc Pellissier, Daniel Stouffer.

Communities assembly rules : going forward

Impact of intra-specific trait variability and spatial scale

In community ecology, species are often thought as homogeneous entities with little functional trait variability. It is however known that plant species that display important trait variability along gradients. Another important feature is the spatial scale at which communities are studied. This is because the impact of some ecological processes such as micro-environmental variability or neighbors competition or facilitation is expected to be blurred at large spatial scales.

During my PhD, I conducted an important field survey in Valloire (France), to study these two features by sampling communities of individuals (rather than species) at various spatial scales. We accessed the contribution of intra-specific trait variability on community diversity to understand the fine ecological processes that are acting between co-occuring individuals depending on the spatial scale.

Refs: Siefert, Violle, Chalmandrier et al. 2015; Chalmandrier et al. 2017

Developing methodologies for diversity patterns analyses

Building expectations – The link between a pattern of diversity and an assembly rule is far from being straightforward. Various ecology processes can explain a diversity pattern making it difficult to interpret its origin. Using a model of community assembly built on strong theoretical hypotheses, I access the efficiency of various statistical methodologies to disentangle assembly rules.

Developing new methodologies – When analyzing the diversity structure of a community or a meta-community, a community ecologist need (at least) two things: a diversity index and a null model. There is however here a (very, very) wide array of possibilities to choose from. A big part of my PhD was to understand the literature on the subject and to come up with new methodologies to use them to capture multiple features of the diversity structure of communities.

Refs: Chalmandrier et al. 2013; Chalmandrier et al. 2015; Ohlmann, Mazel, Chalmandrier et al. 2018

Main collaborators: Laure Gallien, Sébastien Lavergne, Tamara Münkemüller, Marc Ohlmann, Wilfried Thuiller