BiodiversiTREE (US)

The BiodiversiTREE experiment consists of two sites. BiodiversiTREE@SERC was established close to Edgewater (Maryland) in 2013; BiodiversiTREE@SCBI was established near Front Royal (Virginia) in 2014. The goal of the experiment is examining how diversity both within and among tree species influences local and landscape level processes, including above and belowground productivity, soil nutrient retention, soil carbon turnover, resistance to herbivory, and water quality. Most of the BiodiversiTREE@SERC site is a self-contained watershed that has been intensively studied by Smithsonian scientists for over 30 years. The BiodiversiTREE@SCBI site is located on former pasture fields with minimal management.

overview BiodiversiTREE SCBI overview BiodiversiTREE SERC
Squares depict experimental plots and are drawn to scale.
Right: monocultures (white), 4-species plots (yellow), 12-species plots (green), natural regeneration control plots (orange), watershed WS109 and its water-sampling weir (purple)

Both sites are set up using a classic diversity-ecosystem function manipulation design with 16 tree species. The pool of species includes 14 canopy and 2 sub-canopy tree species, coming from the top 20 species by basal area in local forests. Our experimental richness range of 12 or 16 species spans the natural gradient of species diversity found in local forests.

Monoculture plots (n = 2 per species), 4-species plots (n = 10), 12-species plots (n = 18), or 16-species plots (n = 2) are included. Per plot, 145 trees were planted in a square grid with 2 m between the trees and alternating 8 and 9 trees per row. Two plots of the total 64 plots are used as control plots having no tree species planted. To account for edge effects, each plot has a buffer strip of 97 trees in a 2 m band. Tree placement in the poly plots were randomly assigned. Each tree species was ordered from Virginia Department of Forestry's state nursery in Crimora, Virginia, Cold Stream Farms in Michigan, North Carolina Forestry Service nursery, or Lawyer Nursery in Montana. By forming a strong partnership with the local state forester, an agreement with Virginia Department of Forestry supplied a majority of the trees to start the project. Bare root seedlings (6-18'') were chosen to give the best chance of survival and increase success. Seedlings were kept in cold storage until planting began. A 2.5 meter tall fence was also constructed to prevent deer damage during the juvenile trees' life. Gates were incorporated to allow access and maintenance inside the plots. Initial soil samples were taken throughout the plots to determine soil variance.

Monoculture plots (n = 2 per species), 4-species plots (n = 19), or 12-species plots (n = 19) are present. Per plot, 255 trees were planted in a hexagonal grid with 2.4 m between the trees. To account for edge effects, each plot has a buffer strip of 112 trees in a 2.4 m band that will not be sampled. The 4-species plots are arranged on a gradient of all arbuscular mycorrhizal species to all ectomycorrhizal species. Thus, the plots have the same species richness and density, but varying levels of functional diversity. For each species, we used seed sources from both mid-Atlantic populations (similar in latitude to the experimental location), and more southern populations (Florida and Georgia, two USDA growing bands to the south). Each provenance is represented equally in each plot in which the species grows.

Site characteristics

location Front Royal, VA Edgewater, MD
former land use abandoned low-input fields corn agriculture since 1978
altitude 315-389 m 7-28 m
soil type Myersville and Montalto, stony loamy fluviomarine deposits
area 9.7 ha 13 ha
no of plots 64 75
plot size 35 m x 35 m 35 m x 35 m
no of trees planted 10 000 17 850
planting date April 2014 April 2013
diversity variables species richness
functional diversity
species richness
functional diversity
geographic origin
diversity gradient 1, 4, 12, 16 sp.
AM or EM fungi
understorey vs. canopy
1, 4, 12 sp.
AM or EM fungi
northern vs. southern
size species pool 16 16
species pool Acer rubrum, Carya glabra, Castanea dentate, Celtis occidentalis, Corylus americana, Diospyros virginiana, Fagus grandifolia, Fraxinus pennsylvanica, Liriodendron tulipifera, Platanus occidentalis, Prunus serotina, Quercus alba, Q. prinus, Q. rubra, Q. velutina, Tilia americana Acer rubrum, Carpinus caroliniana, Carya alba, C. glabra, Cornus florida, Fagus grandifolia, Fraxinus pennsylvica, Liriodendron tulipifera, Liquidambar styraciflua, Nyssa sylvatica, Platanus occidentalis, Quercus alba, Q. falcata, Q. rubra, Q. velutina, Ulmus americana
contact person William McShea John D. Parker


The four fundamental research questions that will be investigated are: (1) Does tree species diversity affect forest productivity and ecosystem function? (2) Is functional diversity important? (3) How will species and population sources respond to climate change? (4) How does tree diversity impact water quality and quantity? Phase I of the experiment replanted 13 hectares of a self-contained watershed that have been in continuous corn agriculture since 1978, with a similarly long period of monitoring water quantity/quality from an instrumented weir (WS109). In addition, corn is a C4 plant with a different isotopic carbon signature than C3 trees. Thus, we will examine how reforestation affects watershed quality and track changes in soil carbon isotopes through time to estimate the quantity, turnover, and movement of carbon in the soil as the land returns to forest.

Extra information
For more information on the BiodiversiTREE experiment, send an e-mail to the contact persons, , or explore the publications:

  • King RA, Pullen J, Cook-Patton SC, Parker JD (2023) Diversity stabilizes but does not increase sapling survival in a tree diversity experiment. Restoration Ecology 7(5): e13927 -
  • Butz EM, Schmitt LM, Parker JD, Burghardt KT (2023) Positive tree diversity effects on arboreal spider abundance are tied to canopy cover in a forest experiment. Ecology 104(8): e4116-
  • Messier C, Bauhus J, Sousa-Silva R, Auge H, Baeten L, Barsoum N, Bruelheide H, Caldwell B, Cavender-Bares J, Dhiedt E, Eisenhauer N, Ganade G, Gravel D, Guillemot J, Hall JS, Hector A, Hérault B, Jactel H, Koricheva J, Kreft H, Mereu S, Muys B, Nock CA, Paquette A, Parker JD, Perring MP, Ponette Q, Potvin C, Reich PB, Scherer-Lorenzen M, Schnabel F, Verheyen K, Weih M, Wollni M, Zemp DC (2021) For the sake of resilience and multifunctionality, let's diversify planted forests! Conservation Letters e12829 -
  • Devaney JL, Pullen J, Cook‐Patton SC, Burghardt KT, Parker JD (2020) Tree diversity promotes growth of late successional species despite increasing deer damage in a restored forest. Ecology 101(8) e03063 -
  • Griffin EA, Harrison JG, McCormick MK, Burghardt KT, Parker JD (2019) Tree diversity reduces fungal endophyte richness and diversity in a large-scale temperate forest experiment. Diversity 11(12) 234 -

photo planting photo planting
planting of the SCBI site (April 2014) planting of the SERC site (April 2013)

photo planting photo planting photo planting