MyDiv (Germany)

MyDiv stands for Mycorrhizae in tree Diversity effects on ecosystem functioning and trophic interactions. It is a tree diversity experiment planted in Bad Lauchstädt (near Halle, Central Germany) in March 2015. The experiment aims to investigate the significance of aboveground-belowground interactions in tree diversity effects on ecosystem functioning. More specifically, the effects of different mycorrhizal associations on a variety of ecosystem functions and soil food webs are studied.

photo of the MyDiv experiment photo of the MyDiv experiment
The MyDiv site in May 2015 and June 2016


The experiment comprises ten native angiosperm tree species: five that develop associations with arbuscular mycorrhiza (AM) and five that develop associations with ectomycorrhiza (EM). Tree species selection aimed at achieving the highest functional similarity between the two pools with regard to tree height, wood density, specific leaf area, seed mass, leaf C:N ratio, and leaf-out date.
The species were planted in monocultures, 2-species, and 4-species mixtures. At each of the tree diversity levels, communities with only AM, with only EM, or with mixtures of both tree species pools were established. The treatments were randomly distributed within two blocks. The experimental design followed the broken-stick model ending up in five different species combinations per block in all treatments. As the species pool contained more species (5 species) than the highest diversity level (4 species), it is possible to test tree diversity effects without confounding effects of compositional similarity at high tree diversity.
Each plot consists of 140 tree individuals with a planting distance of 1 m. Tree individuals of 2- and 4-species mixtures were planted in a regular distribution pattern with each species being represented in the same proportion. All plots are covered with black water-permeable polypropylene tarp to reduce competition with weeds and the establishment of rodent habitats; the black tarp will be removed after the successful establishment of the experimental plots.

plots of MyDiv
Within-site and within-plot design of the MyDiv site
Aerial photograph: © GeoBasis-DE / LVermGeo LSA, [2014, C22-8029566-8029567-2014-8] (

Site characteristics

location Bad Lauchstädt
former land use agriculture
altitude 115 m
soil type Haplic Chernozem developed from Loess (WRB)
area 1.9 ha
no of plots 80
plot size 11 m x 11 m
no of trees planted 11 200
planting date March 2015
diversity variables species richness
mycorrhizal type
diversity gradient 1, 2, 4 sp.
AM, EM, AM+EM trees
size species pool 10
species pool AM species: Acer pseudoplatanus, Aesculus hippocastanum,
Fraxinus excelsior, Prunus avium, Sorbus aucuparia
EM species: Betula pendula, Carpinus betulus, Fagus sylvatica,
Quercus petraea, Tilia platyphyllos
contact persons Olga Ferlian, Nico Eisenhauer

Soil organisms and aboveground-belowground interactions may be significant drivers of positive plant diversity effects on multiple processes. MyDiv aims at testing this hypothesis by studying the effects of tree mycorrhizal type, a crucial plant functional trait, on the relationship between tree diversity and ecosystem functioning. Furthermore, we aim at unravelling the role of mycorrhiza as food resource in the belowground food web and its effects on food web structure in tree communities with different mycorrhizal types. The main studies will focus on the effects on tree growth and mortality, primary productivity, carbon sequestration, and nutrient cycling as well as on trophic interactions in soil including diversity and structure of soil microbial and soil fauna communities.

Extra information
Send an e-mail to the contact persons, visit the experiment's own website.