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Professeurs

Vincent Maire

Sciences de l’environnement

Université du Québec à Trois-Rivières


Téléphone : 819 376-5011 # 3318
Courriel : vincent.maire@uqtr.ca vmaire24@gmail.com
Lieu d'encadrement : UQTR
Habilitation : Habilitation à diriger

Résumé
Vincent Maire is an early-career Assistant Professor, specializing in soil-plant-climate interactions. After obtaining a doctorate in grassland ecology and ecophysiology (Blaise Pascal University), Maire conducted postdoctoral research at INRA Unité de recherche sur l’ecosystème prairial (France), and at Macquarie University (Australia). Over the past twelve years, Maire’s research focused on the influence of soil fertility on the functional strategies used by plants to adapt to their habitat and coexist within communities in a variety of ecosystems using local and large-scale studies. His research approach relies on the framework of plant functional traits, and, more specifically, leaf photosynthesis traits. His newly established research program at the UQTR is funded through the NSERC Discovery Grants and the FRQNT Établissement de nouveaux chercheurs universitaires programs. Recent publications from his postdoctoral research shed light on an alternative strategy of plants to use water or nitrogen to run leaf photosynthesis according to abiotic conditions and appeared in Ecology Letters and Global Ecology and Biogeography. The latter includes a publicly available Dryad trait data package associated with soil and climate variables.

Références
Contribution 1 – Using fundamental niche to predict plant species abundance within community [Articles A8, A11, A13-17]
Two assembling rules are usually depicted in order to understand how a structured community emerges locally from a regional pool of species: The habitat-filtering (HF) rule selects species from the regional pool because they possess a similar trait syndrome suitable for a given habitat, while the niche differentiation (ND) rule selects species based on their trait dissimilarity limiting the competition and favoring the coexistence between them. We showed that these two rules are not necessarily in opposition but can jointly be at play to explain the abundance of species within grassland communities. HF largely dominated ND under favorable environments, while the ND effect increased with environmental severity. The joint effect of HF and ND on the community structure was possible as each process operated on an independent functional trait. For instance, HF selected dominant species based on plant height under favorable environments, while ND selected coexisting species that displayed a difference in growth precocity with the dominant species. We highlighted the need to better describe the niche of species using a minimum of four independent traits, so that the structure of the community could be highly explained. This work lead to four publications, two of which I was the first lead author. Our theory is now used as a benchmark in my community (Kraft et al. 2014). The theory is now also being used to explain the assembling of anuran communities in animal ecology (VargasSalinas & Amézquita 2013) and even the coexistence of cancerous cells with healthy ones in cellular biology (Yang et al 2013).

Contribution 2 – Plant photosynthetic strategies at the global scale [Articles A2, A5-7, A9-10, A15-16]
Photosynthesis is the source of nearly all energy available to living things. Understanding its adaptation to the constraints of the environment is still one of the most discussed topics in ecophysiology. Collaborating with two international teams, I have extended the development of two theories of photosynthesis through the use of two datasets to better understand its spatial and temporal adaptation by several hundred plant species (TRY & Globamax). Through the theory of the coordination of photosynthesis, we demonstrated that the photosynthetic machinery is actively co-regulated by its two main biochemical limitations (nitrogen and light), when one considers the average environmental conditions experienced by plants during the lifetime of Rubisco. I was the leader of this work (A15). Through the least-cost theory of photosynthesis (A10), we have demonstrated that in opposition to the coordination theory, its biochemical and biophysical (CO2 and H2O transfers between leaf and atmosphere) limitations are completely decoupled, making room for two photosynthetic strategies. The first strategy relies on the different ways of transporting and using water into leaves. The second strategy relies on the different ways of capturing and keeping nitrogen into leaves. The aridity, temperature and elevation of the habitat determine which N or H2O strategy is best suited to maximize carbon fixation for plants. I contributed to this work as a first author publication and as collaborator for different aspects of the theory. Both theories have been included into next-generation models of vegetation dynamics (A16; Wang 2013, 2016), making progress towards a better prediction of the carbon dynamics at community scale and at the global scale.

Contribution 3 – Biotic and abiotic mechanisms of the soil organic matter decomposition [A3, A12, A18]
The soil stores more carbon into soil organic matters (SOM) than is contained in the atmosphere or in the living biomass. We discovered two universal mechanisms, one biotic, the second abiotic, that are able to decompose SOM and release carbon back into the atmosphere in important quantities. Regarding the abiotic mechanism, we showed that endoenzymes released from dead organisms can be stabilized in soil particles and have access to suitable substrates and co-factors to permit a production of CO2 over several months. This result was remarkable, because until then, the CO2 production under ambient atmosphere had always been regarded as intrinsically linked to living cells. This study reveals a 'soil memory' from past microbial communities. This result rapidly generated a debate in literature (e.g. Blankinship et al 2014), but our results were strictly confirmed (Kéraval et al 2016) and the ‘extracellular respiration’ is now measured routinely in soil ecology studies (Sinsabaugh et al 2015). Regarding the biotic mechanism, we have identified a fungal functional strategy that derive the energy obtained from fresh litter to decompose recalcitrant soil organic matter in return for nutrients. The intensity of this mechanism depended on soil fertility. The supply of nutrients obtained from soil organic matter decomposition may help synchronizing plant nutrient requirements. This work is very well cited in the soil ecology community (> 30citations an-1). A second article has been submitted [A3]. My role was that of an academic supervisor for N. Perveen and T. Shazhad, PhDs with S. Fontaine.