ORPHEE (France)

The ORPHEE tree species diversity experiment was established in south-western France in 2008 to investigate biodiversity and ecosystem functioning under the influence of a changing climate. The research focuses on the importance of leaf phenology, using 5 tree species of 2 functional groups (deciduous vs. evergreen).

aerial photo of the ORPEE site 2012
Aerial view of the site in 2015

The research site consists of 8 blocks, with 32 plots in each block. Every possible 1, 2, 3, 4 and 5-species combination was planted in each block; the last plot of a block was also planted with all 5 species. The plots are 20 m x 20 m large, and the planting distance between two trees was 2 m. Thus, 100 trees were planted per plot. The plots are randomly distributed in each block.
Half of the blocks will be irrigated to observe the changes in ecosystem functioning under a changing environment.

plots in one block planting design in a 3-species plot design irrigation treatment ORPEE site
The plots within a block:
1 (light) - 5 (dark) species per plot
Planting design in a 3-species plot Half of the blocks (in blue) will be irrigated.

Site characteristics

location Pierroton
former land use pine stands (Pinus pinaster)
altitude 60 m
soil type sandy podzol on sandstone bedrock
area ca. 12 ha
no of plots 256
plot size 20 m x 20 m
no of trees planted 25 600
planting date January and February 2008
diversity variables species richness
functional diversity
diversity gradient 1, 2, 3, 4, 5 sp.
deciduous, evergreen
species pool deciduous: Betula pendula, Quercus pyrenaica, Quercus robur
evergreen: Quercus ilex, Pinus pinaster
contact person Hervé Jactel

The research will focus on the differences in tree growth and herbivory damage between the two leaf phenology groups and the irrigation treatment. Plant-plant interactions will be studied along the gradient of species richness and functional levels.

Extra information
Send an e-mail to the contact person, visit the experiment online, or explore the publications:

  • Damien M, Jactel H, Meredieu C, Régolini M, Van Halder I, Castagneyrol B (2016) Pest damage in mixed forests: Disentangling the effects of neighbor identity, host density and host apparency at different spatial scales. Forest Ecology and Management 378: 103-110 - doi: 10.1016/j.foreco.2016.07.025
  • Verheyen K, Vanhellemont M, Auge H, Baeten L, Baraloto C, Barsoum N, Bilodeau-Gauthier S, Bruelheide H, Castagneyrol B, Godbold D, Haase J, Hector A, Jactel H, Koricheva J, Loreau M, Mereu S, Messier C, Muys B, Nolet P, Paquette A, Parker J, Perring M, Ponette Q, Potvin C, Reich P, Smith A, Weih M, Scherer-Lorenzen M (2016) Contributions of a global network of tree diversity experiments to sustainable forest plantations. Ambio 45: 29-41 - doi: 10.1007/s13280-015-0685-1
  • Haase J, Castagneyrol B, Cornelissen JHC, Ghazoul J, Kattge J, Koricheva J, Scherer-Lorenzen M, Morath S, Jactel H (2015) Contrasting effects of tree diversity on young tree growth and resistance to insect herbivores across three biodiversity experiments. Oikos 124: 1674-1685 - doi: 10.1111/oik.02090
  • Paine CET, Amissah L, Auge H, Baraloto C, Baruffol M, Bourland N, Bruelheide H, Daïnou K, de Gouvenain RC, Doucet J-L, Doust S, Fine PVA, Fortunel C, Haase J, Holl KD, Jactel H, Li X, Kitajima K, Koricheva J, Martínez-Garza C, Messier C, Paquette A, Philipson C, Piotto D, Poorter L, Posada JM, Potvin C, Rainio K, Russo SE, Ruiz-Jaen M, Scherer-Lorenzen M, Webb CO, Wright SJ, Zahawi RA, Hector A (2015) Globally, functional traits are weak predictors of juvenile tree growth, and we do not know why. Journal of Ecology 103: 978-989 - doi: 10.1111/1365-2745.12401
  • Castagneyrol B, Régolini M, Jactel H (2014) Tree species composition rather than diversity triggers associational resistance to the pine processionary moth. Basic and Applied Ecology 15: 516-523 - doi: 10.1016/j.baae.2014.06.008
  • Castagneyrol B, Giffard B, Péré C, Jactel H (2013) Plant apparency, an overlooked driver of associational resistance to insect herbivory. Journal of Ecology 101: 418-429 - doi: 10.1111/1365-2745.12055

irrigation treatment
One of the ORPHEE blocks in December 2010 The irrigation treatment has started! (May 2015)