Thématiques de recherche

Disantangling the effects of habitat loss and fragmentation
on biodiversity

Habitat loss is arguably the greatest threat to the world’s biodiversity. As human activities involve increasing transformed areas, options to preserve large extents of natural habitats get reduced. The spatial organisation of the remaining habitats (configuration) and the potentiality for organisms to move among habitat remnants in the landscape (matrix permeability) thus appear as critical variables. But the window of opportunity offered by the management of theses variables (configuration and matrix permeability) along with the amount of habitat has been the subject of debate among scientists since the 1970s, thus limiting the possibilities for decision support in spatial planning. The EU-funded SCALED project aims to solve this debate by combining modelling and empirical approaches at various spatial scales and for multiple organisms.

Modeling the impact of climate and land use change in a fragmented landscape

Anthropogenic land use change, caused by increasing needs for energy and resources, is driving dramatic changes in biodiversity, ecosystem functioning and consequently ecosystem services, such as water quality or crop pollination. New quantitative tools are needed to refine our understanding and projections of these processes into the coming century. My current research aims at developing such a tool by adapting and coupling BIOMOVE (Midgley et al. 2010), an existing landscape modelling shell, to North America cold temperate forests in order to simulate landscape and biodiversity dynamics in the Monteregie (a case study region in south west Quebec), a biodiversity-rich area with a highly fragmented landscape.
More info can be found on this project here.

Intraspecific trait variability

Intraspecific functional variability is a highly timely issue in functional ecology. Deciding whether it has to be accounted for in trait-based studies is an open debate. While analysing the trait dataset I collected on alpine plants, I found strong intraspecific trait variability (ITV). This variability was lower than the interspecific one, but not negligible, and resulted partly from environmental effects and could be explained by species distribution models ; ITV also strongly altered the calculation of functional diversity indices. From my results that are published in Biology Letters, Journal of Ecology, Functional Ecology, Oikos and PPEES. I conclude that ITV should be considered more often to strengthen current trait-based approaches.

Development of a modelling shell

BIOMOVE is a landscape modelling shell that simulates, in a spatially and temporally explicit frame, plant species’ geographic range shifts in response to climate, habitat structure and disturbance, at annual time steps. How to couple models (hybridize) for more accurate assessments of vegetation dynamics (species’ ranges) occupied a large part of my past research (Albert et al. 2008a, Thuiller et al. 2008, Midgley et al. 2010, Gallien et al. 2010). The development of such hybrid models is crucial towards the development of biodiversity scenarios in the context of global changes as they provide outstanding tools to overcome past limitations of predictive models (e.g. species distribution models).

Sampling in Ecology

Sampling is a key issue in ecology. Using virtual simulations (collaboration with N.G. Yoccoz), I’ve demonstrated the inefficiency of common sampling designs (e.g. random) to estimate models or complex parameters that are common in ecology (e.g. response curve estimation). I’ve also revealed the importance of selecting appropriate sampling space (e.g. geographic vs. climatic space) and sampling design, and the value of using prior knowledge of the study system (e.g. response-surface methodology) to reveal underlying ecological patterns. These results are published in a special issue of Ecography ; subsequently I was invited to develop these ideas in a book chapter about sampling in landscape genomics. I believe that these findings are crucial for the establishment of strong sampling in ecology and for the development of new theoretical tools aimed towards finer description of ecological patterns.

Vertical Ecology

In collaboration with Patrick Saccone, Sébastien Ibanez, Sébastien Lavergne, Julien Roy, Hanna Secher-Fromell, Roberto Geremia, Jean-Christophe Clément & the Parc National des Ecrins.

High altitude (> 3000 cliffs shelter specific biotic communities that are organized around cushion plants (key-stone species such as Androsace helvetica) and include plant, insect and micro-organisms species. These communities established in climatically extreme habitats (broad temperature range, high levels of solar radiation, violent winds…) are characterized by fragmented populations (only on high summits) and are self-sustained ecosystems (the soil on which they grow essentially comes from their own biomass decomposition). The Vertical Ecology project aims at better understanding the functioning of this interesting system. Our research is organized around two main questions : (1) What is the colonization history of high altitude populations of cushion plants in the Alps since the last glaciation ? (2) What is the consequence of the genetic differentiation between populations on cushion ecosystem functioning (associated biodiversity & biochemical cycles) ?

See the TV reportage here
and the project’s page on the Parc National des Ecrins’ web site.