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Jabot F.,CNRS Biological Evolution and Diversity Laboratory | Jabot F.,Laboratoire dIngenierie pour les Systemes Complexes | Chave J.,CNRS Biological Evolution and Diversity Laboratory
American Naturalist | Year: 2011

The neutral theory of biodiversity challenges the classical niche-based view of ecological communities, where species attributes and environmental conditions jointly determine community composition. Functional equivalence among species, as assumed by neutral ecological theory, has been recurrently falsified, yet many patterns of tropical tree communities appear consistent with neutral predictions. This may mean that neutral theory is a good first-approximation theory or that species abundance data sets contain too little information to reject neutrality. Here we present a simple test of neutrality based on species abundance distributions in ecological communities. Based on this test, we show that deviations from neutrality are more frequent than previously thought in tropical forest trees, especially at small spatial scales. We then develop a nonneutral model that generalizes Hubbell's dispersal-limited neutral model in a simple way by including one additional parameter of frequency dependence. We also develop a statistical method to infer the parameters of this model from empirical data by approximate Bayesian computation. In more than half of the permanent tree plots, we show that our new model fits the data better than does the neutral model. Finally, we discuss whether observed deviations from neutrality may be interpreted as the signature of environmental filtering on tropical tree species abundance distributions. © 2011 by The University of Chicago. Source


Rolland J.,Ecole Polytechnique - Palaiseau | Cadotte M.W.,University of Toronto | Davies J.,McGill University | Devictor V.,Montpellier University | And 11 more authors.
Biology Letters | Year: 2012

The 2011 meeting of the European Ecological Federation took place in Ávila, Spain, from 26th September to 29th September. The French Ecological Society (SFE) and the Foundation for Research on Biodiversity (FRB) sponsored a session entitled 'Evolutionary history, ecosystem function and conservation biology: new perspectives'. We report on the main insights obtained from this symposium. © 2011 The Royal Society. Source


Mathias J.-D.,Laboratoire dIngenierie pour les Systemes Complexes | Bonte B.,Laboratoire dIngenierie pour les Systemes Complexes | Cordonnier T.,IRSTEA | Cordonnier T.,University Grenoble alpes | de Morogues F.,Grenoble Institute of Technology
Environmental Management | Year: 2015

Greater demand for wood material has converged with greater demand for biodiversity conservation to make balancing forest ecosystem services a key societal issue. Forest managers, owners, or policymakers need new approaches and methods to evaluate their ability to adapt to this dual objective. We analyze the ability of forest owners to define sustainable forest management options based on viability theory and a new flexibility index. This new indicator gauges the adaptive capacity of forest owners based on the number of sustainable actions available to them at a given time. Here we study a public forest owner who regulates harvest intensity and frequency in order to meet demand for timber wood at forest scale and to meet a biodiversity recommendation via a minimum permanently maintained volume of deadwood per hectare at stand scale. Dynamical systems theory was used to model uneven-aged forest dynamics—including deadwood dynamics—and the dynamics of timber wood demand and tree removals. Uneven-aged silver fir forest management in the “Quatre Montagnes region” (Vercors, France) is used as an illustrative example. The results explain situations where a joint increase in wood production and deadwoodretention does not reduce the flexibility index more than increasing either one dimension alone, thus opening up ecological intensification options. To conclude, we discuss the value of the new flexibility index for addressing environmental management and ecological intensification issues. © 2015 Springer Science+Business Media New York Source

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