IDENT (Canada, USA, Germany, Italy)

The International Diversity Experiment Network with Trees (IDENT) is a network of Biodiversity - Ecosystem Functioning (BEF) experiments in North America and Europe. The main characteristics of IDENT within TreeDivNet are the focus on the early years of tree development, the role of functional diversity, and BEF relationships over stress gradients. The experiment consists of seven sites: six in temperate ecoregions, one in a Mediterranean region. In total, 1640 plots have been planted with native as well as exotic tree species. At three of the sites, the impacts of water availability and nutrient addition are studied as well.

map with the seven sites of IDENT
The seven sites of the IDENT experiment

aerial view of the Sault-Ste-Marie site
Aerial view of the Sault-Ste-Marie site (August 2014)

Two gradients are established, i.e., a species richness (SR) gradient and a functional diversity (FD) gradient, in order to allow separating the two different diversity effects. The FD gradient consists of species combinations of equal SR but different FD. To enable isolating the effect of FD, as opposed to the impact of the presence/absence of specific species or traits, the FD levels are repeated using different species compositions and are pooled in groups of similar FD value.

SR and FD ranges
Schematic representation of the species richness (SR) and functional diversity (FD) gradients studied in IDENT. Monocultures of all species are always present. Smaller squares behind larger ones indicate replications of the same FD level with different species combinations. The sites may differ in the length of the gradients, and the number of replications within gradients.

On different sites, IDENT also includes additional experimental treatments that are related to the link between climate change, stress gradients and forest resilience, and the interactions between native and exotic species. Water availability is manipulated through irrigation or partial removal of rainfall at two of the sites. Six congeneric pairs of North American and European tree species are planted at four of the sites. The fertilization treatment (1 site) consists of N addition, P addition, and N+P addition. The extra treatments are implemented by doubling the replication of a given FD gradient over a constant SR level to accommodate both a control and a manipulated treatment.

irrigation treatment rain removal
Irrigation and rain removal equipment at the Sault-Ste-Marie site (June 2013, July 2014)

As the focus in IDENT is on the early successional stage of stand development, the trees are planted in high density, i.e., 40 to 50 cm apart, to accelerate species interactions. In most cases, square plots contain 7 x 7 or 8 x 8 trees. At each site, the plots are positioned randomly in a block.

Site characteristics

site Montreal Auclair Cloquet Sault-Ste-Marie Freiburg FAB Macomer
country Canada Canada USA Canada Germany USA Italy
former land use high-input agriculture low-input abandoned agriculture forest low-input abandoned agriculture grassland pasture low-input abandoned fields tree nursery, unused for 5 years
altitude (m) 39 333 383 210 278 279 615
soil type sandy loam sandy loam sandy loam sandy sandy silt loam
area (ha) 0.53 0.34 0.34 1.0 1.1 0.28 0.6
no of plots 216 192 192 184 408 140 308
plot size (m2 16 14.44 14.44 10.24 13 20.25 10.24
no of trees planted 13 824 9408 9408 9016 19 992 8960 19 712
planting date 2009 2010 2010 2013 2013 2013 2014
diversity variables SR, FD SR, FD SR, FD SR, FD, PD SR, FD, PD SR, FD, PD SR, FD, PD
- SR levels 1,2,4,12 1,2,6 1,2,6 1,2,4,6 1,2,4,6 1,2,5,12 1,2,4,6
- FD levels 8 3 3 3 3 4 3
- PD angiosperm/
28 levels evergreen/
treatments native/exotic native/exotic native/exotic water native/exotic
size species pool 19 12 12 6 12 12 12
species pool Abies balsamea, Acer platanoides, A. rubrum, A. saccharum, Betula alleghaniensis, B. papyrifera, Larix decidua, L. laricina, Picea abies, P. glauca, P. omorika, P. rubens, Pinus resinosa, P. strobus, P. sylvestris, Quercus robur, Q. rubra, Tilia cordata, Thuja occidentalis Acer platanoides, A. saccharum, Betula papyrifera, B. pendula, Larix decidua, L. laricina, Picea abies, P. glauca, Pinus strobus, P. sylvestris, Quercus robur, Q. rubra Acer saccharum, Betula papyrifera, Larix laricina, Picea glauca, Pinus strobus, Quercus rubra Acer platanoides, A. saccharum, Betula papyrifera, B. pendula, Larix decidua, L. laricina, Picea abies, P. glauca, Pinus strobus, P. sylvestris, Quercus robur, Q. rubra Acer negundo, Acer rubrum, Betula papyrifera, Juniperus virginiana, Pinus banksiana, Pinus resinosa, Pinus strobus, Quercus alba, Quercus ellipsoidalis, Quercus macrocarpa, Quercus rubra, Tilia americana Acer monspessulanum, Arbutus unedo, Fraxinus ornus, Olea europea, Phillyrea latifolia, Pinus halepensis, P. pinaster, P. pinea, Pistacia lentiscus, Quercus ilex, Q. pubescens, Q. suber

The site established in Macomer, Italy, was established and is maintained with the much welcomed help and support of the "Sant'Antonio Forest nursery in Macomer-Ente Foreste della Sardegna".


The four research foci are relevant measures of diversity, underlying mechanisms and scale dependency, importance of trophic interactions, and BEF effects over environmental gradients. The experiment wants to answer the following questions: (1) How do the different components of diversity, i.e., species richness and functional diversity, contribute to ecosystem functioning? (2) Which species and traits to choose for creating the desired functional diversity gradient? (3) Is complementarity the driving mechanism of overyielding in young tree communities? (4) How does neighbourhood diversity drive the realized FD and trait values? (5) At which spatial and temporal scales do complementarity effects occur? (6) How can we test for trophic-mediated complementarity? (7) How do environmental conditions influence species interactions?


IDENT also invests in public education on the importance of trees and biodiversity. Therefore, IDENT-Cité was created. IDENT-Cité serves as a link between the research done in TreeDivNet and people. For more info about IDENT-Cité, see the pdf.

design IDENT-Cité photo millionth tree
The IDENT-Cité plantation in Montreal. People walk along a gradient of diversity in a double spiral. Maximum diversity is reached at the center, where activities will be held and information panels installed. The millionth TreeDivNet tree, a Pinus parviflora, planted in IDENT-Cité

Extra information

Contact info
IDENT is a network within TreeDivNet, scientifically coordinated by Alain Paquette and Christian Messier. Each site has a local Principal Investigator, who coordinates the local research and maintenance.

Site Contact persons Affiliation
IDENT (general) Alain Paquette
Christian Messier
Centre for Forest Research
Université du Québec à Montréal
P.O. Box 8888, Centre-ville Station
Montreal, QC H3C 3P8 Canada
Auclair Dominique Gravel Département de biologie
Université du Québec à Rimouski
300, Allée des Ursulines
Rimouski, Qc, G5L 3A1 Canada
Cloquet Peter Reich Department of Forest Resources
University of Minnesota
St. Paul, MN 55108, USA
FAB Jeannine Cavender-Bares
Rebecca Montgomery
University of Minnesota
Department of Ecology, Evolution and Behavior; Department of Forest Resources
St. Paul
MN 55108, USA
Freiburg Michael Scherer-Lorenzen
Charles Nock
Jürgen Bauhus
University of Freiburg
Chair of Geobotany
Schaenzlestr. 1
79104 Freiburg, Germany
Macomer Simone Mereu Department of Science for Nature and Environmental Resources
University of Sassari
Via Enrico de Nicola, 9
07100-Sassari, Italy
Montreal Alain Paquette
Christian Messier
Centre for Forest Research
Université du Québec à Montréal
P.O. Box 8888, Centre-ville Station
Montreal, QC H3C 3P8 Canada
Sault-Ste-Marie Bill Parker Ontario Forest Research Institute
1235 Queen St. E.
Sault Ste. Marie, ON, P6A 2E5, Canada


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  • Garbe CM (2013) Tree functional traits. Understanding their variation - from intraspecific plasticity to the effects of trait diversity on ecosystem functioning. PhD thesis, UQAM
  • Van de Peer T, Mereu S, Verheyen K, Costa Saura JM, Morillas L, Roales J, Lo Cascio M, Spano D, Paquette A, Muys B (2018) Tree seedling vitality improves with functional diversity in a Mediterranean common garden experiment. Forest Ecology and Management 409: 614-633 - doi: 10.1016/j.foreco.2017.12.001
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  • Williams LJ, Paquette A, Cavender-Bares J, Messier C, Reich PB (2017) Spatial complementarity in tree crowns explains overyielding in species mixtures. Nature Ecology & Evolution 1: 0063 - doi: 10.1038/s41559-016-0063
  • Nguyen NH, Williams L, Vincent JB, Stefanski A, Cavender-Bares J, Messier C, Paquette A, Gravel D, Reich PB, Kennedy PG (2016) Ectomycorrhizal and saprotrophic fungal diversity are linked to different tree community attributes in a field-based tree experiment. Molecular Ecology 25: 4032-4046 - doi: 10.1111/mec.13719
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Auclair in fall 2010 Macomer in summer 2015 Montreal in fall 2012
The Auclair, Macomer, and Montreal sites one, two, and three years after planting (fall 2010, summer 2015, fall 2012)