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:

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:, 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

Google Analytics

Targeted advertising cookies


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 or by post at:

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

Dernière mise à jour : Mai 2018

Menu Logo Principal IN-SYLVA France ONF FCBA CIRAD CNPF OFB Université de Rouen

Home page

GRAL Network (Altitudinal gradients)

Network name
GRAL Network (Altitudinal gradients)
Coordination :
Network description

Altitudinal gradients provide opportunities for the study of tree adaptation to environmental variations in highly contrasted climatic conditions.

The GRAL Network groups together experimentations on natural populations, provenance tests and reciprocal transplants along altitudinal gradients.

It includes five experimental sites (Pyrenees, Ventoux, Issole, Vésubie, Briançonnais) for four species (oak, beech, larch and silver fir). It includes three types of installations:

  • natural populations (both plots and transects) distributed along altitudinal gradients,
  • provenance tests distributed at different altitudes,
  • reciprocal transplants along altitudinal gradients (Transplants).

In-situ gradients:

  • Larch: 4 plots of 200 mature trees distributed along a gradient of about 1000 m (1350, 1700, 2000, 2300 m) with a weather station in each plot. Phenotypic (microdensitometric profiles 1967-2007) and genetic data (microsatellite markers and SNPs) are available.
  • Oak and Beech: 10 populations per species distributed along two Pyrenean valleys ranging from 100 to 1600 m in elevation. Each stand is equipped with a temperature sensor. Phenological and ecophysiological monitoring are featured.
  • Beech on the Mont Ventoux: 5 populations on the Ventoux gradient from 995 to 1485 m in elevation. Each plot has a temperature sensor. Phenotypic and genetic data are collected.
  • Fir: 15 populations spread over 3 gradients (Ventoux, Issole, Vésubie), from 995 to 1550 m in elevation. Each plot has a temperature sensor. Phenotypic and genetic data are collected.
  • Oak provenance tests: 3 common gardens composed of 10 oak populations are installed at 3 different elevations, 0, 800 and 1800m, for 1000 to 3000 trees per test site.


  • Larch: 120 clones from four different elevations(30 clones each for 1350, 1700, 2000 and 2300 m). Installations of clone comparison tests (5 ramets per clone) planted at the same four altitudes, in 2014 and 2015, near the plots where the multiplied adult trees are located.
  • Oak and Beech: 5 reciprocal transplant sites installed along the Pyrenean altitudinal gradient from 100 to 1600 m with three different populations per species.
  • Silver fir: 9 reciprocal transplant sites are located at low, medium and high elevations along 3 altitudinal gradients (Ventoux, Issole, Vésubie). At each of the sites, 57 families from continuous sampling along each altitude gradient are represented.
  • Beech: 2 reciprocal transplant sites are located at low and high elevation on the Ventoux altitudinal gradient. At each of the sites, 60 families from three populations along the gradient (low, medium and high elevations) are represented.
Services offer

Access to available data

Access to experimental sites for new measurements and observations



Work description

These experimetal sites are particularly intended for the study of local adaptation and phenotypic plasticity. Access is determined according to the specific objectives and interests of each study. In all cases, access is supervised and researchers are assisted by the persons in charge of each experimental site.

Access unit and cost

Costs are determined on a project-by-project basis.


For larch only, each clonal test plots has a mini weather station managed by Agroclim (INRAE). Other devices for monitoring environmental conditions and trees will be installed as soon as possible (probes, cameras, dendrometers).