PhD position OT-28983
Understanding the relation between photosynthesis and sun-induced chlorophyll fluorescence (SIF) of forests
54000
INRAE presentation
The French National Research Institute for Agriculture, Food, and Environment (INRAE) is a major player in research and innovation. It is a community of 12,000 people with 272 research, experimental research, and support units located in 18 regional centres throughout France. Internationally, INRAE is among the top research organisations in the agricultural and food sciences, plant and animal sciences, as well as in ecology and environmental science. It is the world’s leading research organisation specialising in agriculture, food and the environment. INRAE’s goal is to be a key player in the transitions necessary to address major global challenges. Faced with a growing world population, climate change, resource scarcity, and declining biodiversity, the Institute has a major role to play in building solutions and supporting the necessary acceleration of agricultural, food and environmental transitions.
Work environment, missions and activities
Photosynthesis is unfortunately not measurable directly on scales greater than a single plant. The lack of predictability of future photosynthesis is thus one of the largest uncertainties in climate projections (IPCC, 2021).
Chlorophyll fluorescence is an afterglow of photosynthesis and hence tightly linked to Gross Primary Productivity (GPP). Sun-induced chlorophyll fluorescence (SIF) has become the quasi-reference in studies of the carbon cycle and the response of GPP to environmental cues, on the simple basis that remotely-sensed SIF from satellites correlates well with GPP estimated on eddy covariance flux towers on a weekly to monthly scale. Several satellite missions that target SIF are to be launched in the near future such as ESA’s FLEX mission scheduled for 2026. Large-scale GPP can otherwise not be measured directly and not be determined from satellite observations. However, the correlation between GPP and SIF breaks down completely for daily and diurnal observations and the simplified concepts to describe SIF from forest canopies are not valid anymore on such short timescales.
Objective: The PhD project will use model-data fusion to understand mechanistically the observed signal of SIF above forest canopies and its link with GPP of the ecosystem. It will measure for the first time active and passive SIF within a forest canopy, making it possible to describe mechanistically other loss processes in the photosynthesis apparatus. The PhD will model photosynthesis and SIF mechanisticallyand with a radiative transfer within the canopy with different optical properties for photosynthetically active radiation and for SIF. By teaming up with the research project FLORES, which will codevelop the first drone-based SIF instrument for proximal remote sensing, the project will be able to upscale local above-canopy SIF observations to the whole ecosystem and link it with ecosystem GPP. This will make the fast variations of SIF available to study ecosystem photosynthesis and its responses to fast environmental changes such as heat waves.
Detailed information: PhD_SIF_long_en.pdf
Training and skills
We are seeking a motivated candidate that likes to combine biology with physics, i.e. combining biochemical modelling at the leaf level with physical modelling at the canopy scale. All quantitative analyses will use mechanistic modelling with MuSICA so strong computer skills and an aptitude for physics will be required. As the project uses model-data fusion, active participation in two measurement campaigns will be essential. There should be an interest in research related to climate change and an affinity to work with international partners.
The thesis will take place for three years at the UMR Silva on the campus of INRAE near Nancy (54280 Champenoux) from autumn 2026 onwards.
INRAE's life quality
By joining our teams, you benefit from (depending on the type of contract and its duration):
- up to 30 days of annual leave + 15 days "Reduction of Working Time" (for a full time);
- parenting support: CESU childcare, leisure services;
- skills development systems: training, career advise;
- social support: advice and listening, social assistance and loans;
- holiday and leisure services: holiday vouchers, accommodation at preferential rates;
- sports and cultural activities;
- collective catering.
How to apply
To apply, please send a cover letter, a CV, the transcript of grades of the master (or of the 3 years of engineering school), a contact information of an academic reference, as well as a résumé (300 words) of the master topic (or of the end-of-study internship) to Matthias Cuntz – matthias.cuntz@inrae.fr
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