Contrasting the effects of environment, dispersal and biotic interactions to explain the distribution of invasive plants in alpine communities.
Despite considerable efforts devoted to investigate the community assembly processes driving plant invasions, few general conclusions have been drawn so far. Three main processes, generally acting as successive filters, are thought to be of prime importance. The invader has to disperse (1stfilter) into a suitable environment (2ndfilter) and succeed in establishing in recipient communities through competitive interactions (3rdfilter) using two strategies: competition avoidance by the use of different resources (resource opportunity), orcompetitive exclusionof native species. Surprisingly, despite the general consensus on the importance of investigating these three processes and their interplay, they are usually studied independently. Here we aim to analyse these three filters together, by including them all: abiotic environment, dispersal and biotic interactions, into models of invasive species distributions. We first propose a suite of indices (based on species functional dissimilarities) supposed to reflect the two competitive strategies (resource opportunity and competition exclusion). Then, we use a set of generalised linear models to explain the distribution of seven herbaceous invaders in natural communities (using a large vegetation database for the French Alps containing 5,000 community-plots). Finally, we measure the relative importance of competitive interaction indices, identify the type of coexistence mechanism involved and how this varies along environmental gradients. Adding competition indices significantly improved model's performance, but neither resource opportunity nor competitive exclusion were common strategies among the seven species. Overall, we show that combining environmental, dispersal and biotic information to model invasions has excellent potential for improving our understanding of invader success.
Univ. Grenoble Alpes, Laboratoire d'Ecologie Alpine (LECA), F-38000 Grenoble, France ; CNRS, Laboratoire d'Ecologie Alpine (LECA), F-38000 Grenoble, France ; Swiss Federal Research Institute WSL, 8903 Birmensdorf, Switzerland.
Laure
L
Gallien
Univ. Grenoble Alpes, Laboratoire d'Ecologie Alpine (LECA), F-38000 Grenoble, France ; CNRS, Laboratoire d'Ecologie Alpine (LECA), F-38000 Grenoble, France.
Florent
F
Mazel
Univ. Grenoble Alpes, Laboratoire d'Ecologie Alpine (LECA), F-38000 Grenoble, France ; CNRS, Laboratoire d'Ecologie Alpine (LECA), F-38000 Grenoble, France.
Sébastien
S
Lavergne
Univ. Grenoble Alpes, Laboratoire d'Ecologie Alpine (LECA), F-38000 Grenoble, France ; CNRS, Laboratoire d'Ecologie Alpine (LECA), F-38000 Grenoble, France.
Julien
J
Renaud
Station Alpine Joseph Fourier, CNRS, Univ. Grenoble, F-38000 Grenoble, France.
Rolland
R
Douzet
Univ. Grenoble Alpes, Laboratoire d'Ecologie Alpine (LECA), F-38000 Grenoble, France ; CNRS, Laboratoire d'Ecologie Alpine (LECA), F-38000 Grenoble, France.
Wilfried
W
Thuiller
alien species; competitive exclusion; dispersal; environmental filtering; niche model; resource opportunity