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31326 Castanet Tolosan CEDEX - France

Dernière mise à jour : Mai 2018

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GRAL network (Altitudinal gradients)

Network and its devices names
GRAL network (Altitudinal gradients)
Coordination :
Network description

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

The GRAL network groups together devices such as 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 pectinated fir). It includes three types of installations:
  • natural populations (plots and transects) distributed along altitudinal gradients
  • tests of provenances distributed at different altitudes (tests of provenances)
  • reciprocal transplants along altitudinal gradients (Transplants).

In-situ gradients:
  • Larch: four plots of 200 mature trees distributed along a gradient of about 1000 m (1350, 1700, 2000, 2300 m). A meteorological station in each plot. Phenotypic (microdensitometric profiles 1967-2007) and genetic data (microsatellite markers and SNPs)
  • Oak and Beech: 10 populations per species distributed along two Pyrenean valleys ranging from 100 to 1600 m altitude. Each population is equipped with a temperature sensor. Phenological and ecophysiological monitoring.
  • Beech on the Mont Ventoux: 5 populations on the Ventoux gradient (from 995 to 1485 m.) Temperature sensor in each plot. Phenotypic and genetic data
  • Fir: 15 populations spread over 3 gradients (Ventoux, Issole, Vésubie), from 995 to 1550 m altitude. Temperature sensor in each plot. Phenotypic and genetic data
  • Oakprovenancetests: three common gardens installed at 3 different altitudes, 0, 800 and 1800m and composed of 10 oak populations from the altitudinal gradient, i.e. 1000 to 3000 trees per test.

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

Access to available data

Access to devices for new measurements and observations



Work description and access modalities

These devices are particularly intended for the study of local adaptation and phenotypic plasticity. Access modalities are to be determined according to the specific objectives and characteristics of interest of each study. In all cases, access will be supervised and assisted by the persons in charge of each device.

Access unit and cost

Costs determined according to each project


Larch: each of the clonal tests of the transplant device has a mini meteorological station managed by Agroclim (INRAE). Other facilities for monitoring environmental conditions and the state of the trees will be installed as soon as possible (probes, cameras, dendrometers).