Facilitation among plants in the tropics: revisiting the conceptual framework of plant plant interactions
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Actions thématiques
structurantes de
l’IRD
Workshop
Facilitation among plants in the tropics: revisiting the
conceptual framework of plant‐plant interactions
Participants (18, alphabetical order): Fabien Anthelme (AMAP, IRD, La Paz, Bolivia), Nicolas
Barbier (AMAP, IRD, Montpellier, France), Daniel Barthélémy (Dir. BIOS, CIRAD), Rob Brooker
(The James Hutton Institute, Aberdeen, Scotland), Lohengrin Cavieres (Université de Concepción,
Chile), Philippe Choler (LECA, CNRS, Grenoble, France), Pierre Couteron (AMAP, IRD, Montpellier,
France), Olivier Dangles (BEI, IRD, La Paz, Bolivia), Roberto Geremia (LECA, Grenoble), Sonia Kéfi
(ISEM, CNRS Montpellier, France), Pierre Liancourt (U. Pennsylvania), Ramiro Lopez (Universidad
La Serena (Chile) & U. San Andres, La Paz, Bolivia), Stéphanie Manel (Université Aix‐Marseille &
AMAP, Montpellier, France), Richard Michalet (EPOC, Université Bordeaux, France), François
Munoz (AMAP, Université Montpellier, France), Julien Roy (LECA, Grenoble), Florian Schneider
(ISEM, CNRS Montpellier, France), Marc‐André Sélosse (Muséum d’Histoire Naturelle de Paris,
France).Montpellier (France), 11‐13 June 2013
Context
Positive, non‐trophic interactions among plants (facilitation) are a major process in the organization
and the dynamics of plant communities. Since 10‐20 years, facilitation has been fully incorporated in
the conceptual framework of ecology, especially across the stress‐gradient hypothesis (SGH). This
hypothesis predicts that positive interactions will increase along with increasing environmental
stress. However, the multiplication of studies testing the SGH worldwide has recently evidenced a
few apparent discrepancies, among which (1) a possible reduction in the intensity of facilitation at
the end of aridity gradients, (2) the observation of intense facilitation in productive (thus not
stressful) environments, and (3) the hypothesis that facilitation may remain intense under the effects
of global warming in alpine environments. Because of their distinctive environmental characteristics
in comparison with extratropical ecosystems, tropical ecosystems are expected to display original
patterns and mechanisms of plant‐plant interactions, e.g. across different architectures in interacting
plants. Their characterization and their inclusion into theoretical ecology may help providing a better
understanding of patterns and mechanisms of plant‐plant interactions. Nevertheless, studies
focusing on facilitation in tropical environments are not frequent. Most of all, they are seldom
connected with the conceptual framework of plant‐plant interactions.
Aims of the workshop
Discuss the state of art of current knowledge on plant‐plant interactions in the (sub) tropics.
Incorporate this empirical knowledge into the conceptual framework of plant‐plant
interactions, across the redaction of a review paper.
Develop the North‐South and South‐South networks on the thematic of plant‐plant
interactions, especially in the Andes.
Some available results in the tropics
We showed at the end of an aridity gradient in the Sahara that the existence of intense
facilitation was caused by herbivores, not by aridity, providing a potential explanation to the collapse
of facilitation at the end of aridity gradients. In a wet tropical zone, we observed that facilitation
among plants was generated by the combined effects of deforestation and herbivory, evidencing that
these factors may generate intense facilitation in productive environments. In an Andean alpine
desert, we evidenced that the outcome of plant interactions was primarily driven by the architecture
of facilitating species, at both interspecific and intraspecific levels (Anthelme & Dangles 2012 in
Perspectives in Plant Ecology, Evolution, and Systematics). Such exploratory data suggest that the
stress‐interaction relationship is about to be strongly modulated by the architecture of interacting
plants. The results were obtained thanks to the specific environmental characteristics that shape
tropical ecosystems. They may permit, to a certain extent, to resolve some of the major the
discrepancies found in the SGH.Some research areas that urgently need to be investigated
Microorganisms, including mycorrhiza, are increasingly recognized as drivers of plant‐plant
interactions. Nevertheless, because of lack of data, it remains obscure to what extent this
assumption applies to tropical environments. Climate change is expected to affect tropical alpine
regions more intensively than extratropical alpine regions. However, the impact of this accelerated
warming on plant‐plant interactions remains virtually unknown in the alpine tropics (but see Cavieres
& Sierra‐Almeida 2012 in Oecologia). There is increasing evidence that positive plant‐plant
interactions impact the diversity of plants at genetic level (see, e.g., Butterfield et al. 2013 in Ecology
Letters). However, most data concern extratropical regions. Taking into account tropical regions and
their specific characteristics (e.g. the continuum of alpine habitats in the tropical Andes, but their
fragmentation when considering wetlands) will certainly help broadening our understanding on
these points.Detailed program
Tuesday 11 June
10:00 Extended morning session (HDR defence)
Inclusion of facilitative processes among plants in the Tropics into the conceptual framework
of plant‐plant interactions (IRD centre, Agropolis).
Fabien Anthelme, AMAP, IRD, Bolivia.
13:00 Lunch at CIRAD
14:00 Introduction to the workshop (batiment PS2 CIRAD)
Pierre Couteron, head of AMAP, IRD, France.
14:15 General insight on plant‐plant interactions
Including studies of plant‐plant interactions in the tropics into “global” conceptual
frameworks: the why and the how
Rob Brooker, the James Hutton Institute, UK.
14:45 (Sub)tropical dry environments
Facilitation, ecosystem functioning and indicators of degradation: comparison inside and
outside the tropics.
Sonia Kéfi, ISEM, CNRS, France.
Landscape‐scale spatially periodic patterns in the dry tropics: an outcome from plant‐plant
facilitation and competition?
Pierre Couteron & Nicolas Barbier, AMAP, IRD, France.
Plant‐plant interactions along environmental gradients in the Andean prepuna.
Ramiro Lopez, Universidad Mayor San Andres, Bolivia & Universidad La Serena, Chile.
16:15 Coffee break
16:30 (Sub)tropical alpine environments
Patterns and mechanisms of facilitation involving cushions in the subtropical Andes (33°S).
Lohengrin Cavieres, University of Concepcion, Chile.
Facilitation in a species‐rich insect community in the alpine tropics.
Olivier Dangles, UR BEI, IRD, Bolivia.
Wednesday 12 June9:00 Broadening our understanding on plant‐plant interactions in tropical regions (1) (batiment
PS2 CIRAD)
The mycorrhizal symbiosis as a network linking plants.
Marc‐André Sélosse, MNHN, France
Alpine cushion plants shape bacterial and fungal communities
Julien Roy, Roberto Geremia & Philippe Chole, LECA, CNRS, France.
10:00 Coffee break
10:20 Broadening our understanding on plant‐plant interactions in tropical regions (2)
Plant‐plant interactions and intraspecific biodiversity: the landscape genetics approach.
Stéphanie Manel, Université Aix‐marseille & AMAP, France.
Partitioning net interactions along altitudinal gradients in Alpine grasslands to study
community responses to climate change
Richard Michalet, EPOC, INRA, France.
11 :20 Synthesis of the presentations
12 :00 Lunch at CIRAD
13:00 Transport to Lauret (20 km north of Montpellier), at l’Auberge du Cèdre.
13:30 Drawing up a plan for a review paper on the inclusion of data on facilitation in the tropics
into the conceptual framework of plant‐plant interactions. Identification of teams (2‐3 people
each) in charge of the chapters of the paper. Teams will work together during the afternoon
and during the next few weeks.
17:30 Visit of a wine cellar in Lauret: le domaine de Cazeneuve
(http://www.cazeneuve.net/Presentation.asp).
20:00 Dinner at l’Auberge du Cèdre.
Thursday 13 June
9:00 Field trip in the « garrigue », typical ecosystem of the region of Montpellier (Pic Saint‐Loup
and Domaine de Restinclières (François Munoz & Pierre Couteron).
13:00 Closure of the workshop, return of participants (Montpellier, airport, train station).You can also read
