ARCHI theme - Diversity and Plasticity of Growth Forms and Architectural Features

Description

Background

The Architectural approach examines the differentiation and organization of axis systems at the scale of the entire plant and during its development. Many studies carried out in the past have made it possible to accumulate a broad knowledge of the mechanisms that establish and organize axes on a wide variety of plants and in many environments (tropical and Mediterranean in particular). Our work on the architectural plasticity of trees and shrubs at the structural (spatial) levels has shown response strategies that may depend on the growth form. Many of these architectural characteristics are modulated by environmental factors and directly influence the ability of plants to persist, migrate or even become invasive. At a finer scale of understanding, the mechanisms of plant construction, the processes of organogenesis and elongation are not all influenced at the same time by environmental factors. It is also interesting to consider cambial reactivation (xylogenesis), because although it is well studied in its relationship to climate, it remains poorly analyzed in terms of primary processes and even less in terms of its expression in the overall architecture of plants and in terms of dynamic mapping and the root-stem organisation.

Objectives

  •  Define the strategies and mechanisms for reiteration involved in the construction, ageing and reactivity of the architectures of the different forms of growth;
  •  The temporal dimension (phenology) of the fundamental processes (elongation, branching, axis thickening) recently addressed in temperate and tropical zones shows very promising capacities of architectural analysis as a key to reading and predicting the interactions between environment and plant structures. Begin to explore these relationships in the root component of plants, which remains a little discussed topic.
  •  Studies in community ecology, biogeography and taxonomy use selected morphological and functional traits to characterize their fitness or competition between organisms as well as assessing phylogenetic relationships between species. How are architectural characters distributed in plant groups? What is the explanatory role of these characteristics and their plasticity in these questions?
  •  The effectiveness of the approaches depends on the relevance of the features selected, which must be both representative of the problem studied and easy to study. Determining the level of architectural responses, global versus specific, according to the factor of the environment considered and the form of growth is a major challenge in analysing and understanding the contribution of architectural features in the ecology of species and communities;
  •  By understanding the ordering of growth and branching processes, we contribute to modelling approaches that take into account the construction and reaction of plant architectures, such as how plant architecture affects plant production and biomass?

Expected Results

  •  Phenotypic diversity and variability: Acquire data on (1) the mechanisms of construction of various growth forms, (2) the genetic variability of architectures, (3) the variability during ontogeny, (4) the modalities and variability of expression of reiteration;
  •  Plasticity: Describe the overall response of different architectures to changes in the environment. How are primary vs. secondary growth priorities managed in response to environmental changes?
  •  Develop stochastic structure-function causal models to simulate interspecific structural variability and relative plasticity related to environmental conditions.
  •  Architectural features: They should be defined according to the plant's organizational levels and the ecological functions concerned. And to adapt this information according to the intended field of application.
  •  Dissemination: Establish and make available practical methods for describing and dating plant architecture. Archive and organize, in databases, information on plant architecture to provide access to the architectural characteristics of each species.

Significant events

  •  Creation of a set of digital educational resources: « Plant growth architecture and production dynamics » (http://greenlab.cirad.fr/GLUVED) ;
  •  Publication of two reference works capitalizing on more than 40 years of research on plant modelling, published by QUAE (Barthélémy et al. 2016, de Reffye et al. 2018). An extended version is available in epub (https://doi.org/10.19182/quae/00001) ;
  •  Philippe de Reffye obtained the gold medal of the Académie Française d'Agriculture (June 2016).

Main funded projects

Acronym Title Duration
IDROPimagerie Intelligente par DRone pour la gestion des écosystèmes forestiers trOPicaux2018 - 2021
PIXIESBordered pits provide a mechanistic understanding of embolism resistance in branch and leaf xylem of tropical rainforest trees from French Guyana2018 - 2019
DIAGARCHI2Outils pour le diagnostic architectural2017 - 2019
TERRETERRE: Training Engineers and Researchers to Rethink geotechnical Engineering for a low carbon future2015 - 2019
DIAGARCHIOutils pour le diagnostic architectural 2015 - 2016

Thèses soutenues

  •  Lehnebach, R. 2015 Study of the ontogenic variability of the sapwood/duramen profile in some tropical forest species in French Guiana. Thesis ED Gaia, University of Montpellier (Dir E. Nicolini, CIRAD Allocation). Become: Post-doctoral fellowship Univ. gent, Belgium ;
  •  Buissart, F. 2015. Modelling the direct and delayed effects of climate change on primary growth and architecture of Mediterranean conifers. Thesis Univ. Aix-Marseille (Co-Director E. Nicolini & M. Vennetier, IRSTEA Research Grant) Become: Medical school.
  •  Millan, M. 2016. Analysis of the variability of architectural features of growth forms in plant communities. Thesis ED Gaia, University of Montpellier (Co-Director C. Edelin & N. Rowe, TAFER Project). Become: Post-doctoral fellowship Univ. Witwatersrand, South Africa
  •  Tondjo, K 2016. Analysis and Modeling of structure-function relationships in teak (Tectona grandis) plantation in Togo. Thesis Univ. Lomé, Togo (Dir T. Fourcaud, CIRAD Research Grant). Become: Univ. teacher-researcher Lomé, Togo

Theses in progress

  •  Levionnois, S. 2016-2019. Plasticity of tree functioning and hydraulic architecture in the face of drought: case study in Guyana's tropical rainforest. Thesis Univ. Guyana (Co-Director E. Nicolini & P. Heuret, LabEx CEBA Research Grant).

Main scientific production (ACL only)

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