Papers by Philippe CHOLER
Arctic, Antarctic, and Alpine Research, Jan 1, 2005
Biogeosciences, 2010
Modelling leaf phenology in water-controlled ecosystems remains a difficult task because of high ... more Modelling leaf phenology in water-controlled ecosystems remains a difficult task because of high spatial and temporal variability in the interaction of plant growth and soil moisture. Here, we move beyond widely used linear models to examine the performance of low-dimensional, nonlinear ecohydrological models that couple the dynamics of plant cover and soil moisture. The study area encompasses 400 000 km 2 of semi-arid perennial tropical grasslands, dominated by C 4 grasses, in the Northern Territory and Queensland (Australia). We prepared 8-year time series (2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008) of climatic variables and estimates of fractional vegetation cover derived from MODIS Normalized Difference Vegetation Index (NDVI) for 400 randomly chosen sites, of which 25% were used for model calibration and 75% for model validation.
Proceedings of The National Academy of Sciences, 2003
Understanding what causes the decreasing abundance of species at the margins of their distributio... more Understanding what causes the decreasing abundance of species at the margins of their distributions along environmental gradients has drawn considerable interest, especially because of the recent need to predict shifts in species distribution patterns in response to climatic changes. Here, we address the ecological range limit problem by focusing on the sedge, Carex curvula, a dominant plant of high-elevation grasslands in Europe, for which two ecologically differentiated but crosscompatible taxa have been described in the Alps. Our study heuristically combines an extensive phytoecological survey of alpine plant communities to set the niche attributes of each taxon and a population genetic study to assess the multilocus genotypes of 177 individuals sampled in typical and marginal habitats. We found that ecological variation strongly correlates with genetic differentiation. Our data strongly suggest that ecologically marginal populations of each taxon are mainly composed of individuals with genotypes resulting from introgressive hybridization. Conversely, no hybrids were found in typical habitats, even though the two taxa were close enough to crossbreed. Thus, our results indicate that genotype integrity is maintained in optimal habitats, whereas introgressed individuals are favored in marginal habitats. We conclude that gene flow between closely related taxa might be an important, although underestimated, mechanism shaping species distribution along gradients.
Oikos, 2004
Plant communities have traditionally been viewed as either a random collection of individuals or ... more Plant communities have traditionally been viewed as either a random collection of individuals or as organismal entities. For most ecologists however, neither perspective provides a modern comprehensive view of plant communities, but we have yet to formalize the view that we currently hold. Here, we assert that an explicit re-consideration of formal community theory must incorporate interactions that have recently been prominent in plant ecology, namely facilitation and indirect effects among competitors. These interactions do not support the traditional individualistic perspective. We believe that rejecting strict individualistic theory will allow ecologists to better explain variation occurring at different spatial scales, synthesize more general predictive theories of community dynamics, and develop models for community-level responses to global change. Here, we introduce the concept of the integrated community (IC) which proposes that range from highly natural plant communities individualistic to highly interdependent depending on synergism among: (i) stochastic processes, (ii) the abiotic tolerances of species, (iii) positive and negative interactions among plants, and (iv) indirect interactions within and between trophic levels. All of these processes are well accepted by plant ecologists, but no single theory has sought to integrate these different processes into our concept of communities.
Journal of …, Jan 1, 2009
Arctic, Antarctic, and …, Jan 1, 2002
Basic and Applied Ecology, Jan 1, 2008
Plant Ecology, Jan 1, 2009
Journal of Vegetation Science, Jan 1, 2002
Journal of …, Jan 1, 2007
Annals of botany, Jan 1, 2008
Journal of …, Jan 1, 2006
Journal of …, Jan 1, 2006
Journal of Vegetation …, Jan 1, 2007
Diversity and Distributions, Jan 1, 2008
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Papers by Philippe CHOLER