Know more

Our use of cookies

Cookies are a set of data stored on a user’s device when the user browses a web site. The data is in a file containing an ID number, the name of the server which deposited it and, in some cases, an expiry date. We use cookies to record information about your visit, language of preference, and other parameters on the site in order to optimise your next visit and make the site even more useful to you.

To improve your experience, we use cookies to store certain browsing information and provide secure navigation, and to collect statistics with a view to improve the site’s features. For a complete list of the cookies we use, download “Ghostery”, a free plug-in for browsers which can detect, and, in some cases, block cookies.

Ghostery is available here for free: https://www.ghostery.com/fr/products/

You can also visit the CNIL web site for instructions on how to configure your browser to manage cookie storage on your device.

In the case of third-party advertising cookies, you can also visit the following site: http://www.youronlinechoices.com/fr/controler-ses-cookies/, offered by digital advertising professionals within the European Digital Advertising Alliance (EDAA). From the site, you can deny or accept the cookies used by advertising professionals who are members.

It is also possible to block certain third-party cookies directly via publishers:

Cookie type

Means of blocking

Analytical and performance cookies

Realytics
Google Analytics
Spoteffects
Optimizely

Targeted advertising cookies

DoubleClick
Mediarithmics

The following types of cookies may be used on our websites:

Mandatory cookies

Functional cookies

Social media and advertising cookies

These cookies are needed to ensure the proper functioning of the site and cannot be disabled. They help ensure a secure connection and the basic availability of our website.

These cookies allow us to analyse site use in order to measure and optimise performance. They allow us to store your sign-in information and display the different components of our website in a more coherent way.

These cookies are used by advertising agencies such as Google and by social media sites such as LinkedIn and Facebook. Among other things, they allow pages to be shared on social media, the posting of comments, and the publication (on our site or elsewhere) of ads that reflect your centres of interest.

Our EZPublish content management system (CMS) uses CAS and PHP session cookies and the New Relic cookie for monitoring purposes (IP, response times).

These cookies are deleted at the end of the browsing session (when you log off or close your browser window)

Our EZPublish content management system (CMS) uses the XiTi cookie to measure traffic. Our service provider is AT Internet. This company stores data (IPs, date and time of access, length of the visit and pages viewed) for six months.

Our EZPublish content management system (CMS) does not use this type of cookie.

For more information about the cookies we use, contact INRA’s Data Protection Officer by email at cil-dpo@inra.fr or by post at:

INRA
24, chemin de Borde Rouge –Auzeville – CS52627
31326 Castanet Tolosan CEDEX - France

Dernière mise à jour : Mai 2018

Menu Logo Principal AgroParisTech

Welcome to ECOSYS

UMR ECOSYS - Ecologie fonctionnelle et écotoxicologie des agroécosystèmes

2013-2016 CALSIF

Calcif
CALSIF

Funding :

ANR Blanc

Contact EcoSys :

Michaël Chelle

Abstract :

Vegetation plays a fundamental role in the functioning of land surfaces. A better understanding of the interactions between vegetation and atmosphere that would allow predicting the response of vegetation to future climate change is mandatory to design mitigation strategies. In this framework, remote sensing of vegetation mainly focused on the analysis of reflected sunlight in the optical domain to derive canopy biophysical variables, such as leaf area index, the fraction of reflected (albedo) or absorbed (fAPAR) radiation, or the content in chlorophyll pigments.

Chlorophyll fluorescence is considered as a complementary observation compared to others based on reflectance. It is very promising since it is widely used to characterize the functioning of photosynthesis, which is a key parameter of the carbon cycle. Fluorescence emission occurs by a mechanism reverse to the absorption that directly competes with the photochemical conversion. This is the reason why fluorescence yield is closely linked to photosynthetic efficiency. Fluorescence yield variations can be directly monitored by active methods, because illumination conditions are well controlled. However, remote sensing of fluorescence with active techniques has been limited by the power of available excitation sources. During the last decade, a passive technique for measuring the sun-induced fluorescence (SIF) has been developed, and successfully applied for quantifying the fluorescence from space in the GOSAT mission. This technique is based on the analysis of the spectral absorption bands in the red and far red. Recently, ESA has selected the FLEX mission dedicated to fluorescence remote sensing. However, if the feasibility of measuring fluorescence from space has now been demonstrated, the interpretation of canopy fluorescence in terms of eco-physiological status still remains unclear.

The purpose of this proposal is to develop the experimental and theoretical tools that will remove this bottleneck. We propose to develop a new instrument for measuring simultaneously the sun-induced and the laser-induced fluorescence (LIF) on the same target. LIF will enable the assessment of changes in the fluorescence yield, which is the true variable directly linked to photosynthesis efficiency, thus filling the gap between SIF and physiological status. In addition, the instrument will also measure: (i) vegetation reflectance spectrum to derive leaf area index, fAPAR or chlorophyll content, and (ii) the canopy vertical structure by monitoring the backscattered laser pulse. In parallel, we propose to develop a canopy fluorescence model to interpret sun-induced and laser-induced fluorescence measurements.

Experimental studies will be carried on crops with different carbon metabolism (C3, C4). The obtained relationship between canopy fluorescence and photosynthesis will be tested against natural vegetation during airborne experiments. At the end of the project, the tools allowing to accurately measure and simulate canopy fluorescence signal will be made available to the scientific community. The outcomes of the project will from a strong scientific basis for the interpretation of fluorescence from space with data from FLEX, GOSAT or OCO-2. 

Project website