Individual-based modelling of tropical forests :
role of biodiversity and responses to drought
Amazonian forests are critical for providing, supporting and regulating global ecosystem services. However, empirical evidence for their vulnerability to climate change has been accumulating over the past decade. In particular, the 2005 and 2010 droughts over the Amazon illustrated this phenomenon. Such droughts have been predicted to increase in frequency and intensity. It is thus critical to better quantify and model tropical forests ability to withstand or adapt to these changes.
Until now, the diversity of species and their interactions and responses to environment has been poorly accounted in vegetation models such as Dynamic Global Vegetation Models. However, the high functional diversity that could result from the high species diversity of tropical forests could enhance their ability to answer and adapt to environmental stresses.
The broad aim of my PhD project is to analyze and model a tropical forest dynamics, and in particular under water stress, taking into account the wide functional and species diversity that these ecosystems shelter.
In a first part of my PhD, I aim at documenting and quantifying the physiological drought resistance (tolerance or avoidance) of Amazonian trees and its diversity. This work benefits from great collaboration with Megan Bartlett and Lawren Sack (UCLA), funds from the LabEx CEBA and field work at the Nouragues station, French Guiana. You could find here a little home-made 8-min movie about one of our field session.
This exploration feeds a second part of my PhD, in which I aim at developing a spatially-explicit and individual-based model of tropical forests. This is a mechanistic-based model, with species-specific parameters. This work is based on a model initially developed by Jérôme Chave.
Maréchaux I., Rodrigues A.S.L., Charpentier A. (in press). The value of coarse species range maps to inform local biodiversity conservation in a global context Ecography
Maréchaux I., Bartlett M., Gaucher P., Sack L., Chave J. (2016). Causes of variation in leaf-level drought tolerance within an Amazonian forest. Journal of Plant Hydraulics 3:e004.
Maréchaux, I., Bartlett, M. K., Sack, L., Baraloto, C., Engel, J., Joetzjer, E., & Chave, J. (2015). Drought tolerance as predicted by leaf water potential at turgor loss point varies strongly across species within an Amazonian forest. Functional Ecology 29 : 1268-1277.
A podcast interview about this study is available on the website of Functional Ecology or at this link.
In 2012, I worked with Ana Rodrigues and Anne Charpentier at the CEFE-CNRS, in Montpellier, France. We explored the following topic :
"From thinking gloabally to acting locally, how to make the best use of limited available biodiversity data in identifying priorities for conservation ?"
In 2013, I worked with Florent Taberlet from the WWF-Guyane, French Guiana and Audrey Coreau from AgroParisTech, Paris, France. With a social science approach (using the framework of Strategic Environmental Management), we explored the following topic :
"Guyanese forests adaptation to climate change : who can act and why ? From the emergence of an environmental issue to its place on the agenda."
More information on this project is available here and here.
Before my PhD, I made undergraduate studies in mathematics and physics, at Ecole Polytechnique, near Paris, France, and then passed a master degree in ecology, evolution and conservation sciences in Paris, France (Paris VI-ENS-AgroParisTech-MNHN).