The Ecotron Experiment (Eisenhauer et al. 2019) a core experiment of the current Research Unit, where all subprojects will work together in concerted campaigns. It will be conducted in 2022 in the iDiv Ecotron facility from iDiv and the Helmholtz Centre for Environmental Research (UFZ). This indoor research facility houses a set of 24 identical experimental units, called EcoUnits, each of which can harbor one to four isolated ecosystems confined in compartments. The Ecotron allows for the construction of complex ecosystems resembling near-natural conditions but with the possibility to eliminate or reduce the variance from unknown factors (e.g., by controlling environmental conditions) and to easily measure most of the variables influencing ecological processes and, thus, the mechanisms underlying biodiversity–ecosystem functioning relationships.
In spring 2022, we will excavate two monoliths of each of 22 selected plots of the former Trait-Based Experiment (Ebeling et al. 2014) covering a gradient from 1 to 3 plant species, and additional four monoliths of a selected 6 species plot (48 monoliths in total). The monoliths will have a depth of 0.8 m and a diameter of 0.5 m, and will be used for two Ecotron treatments with soil history. In addition, we will excavate 48 monoliths from the bare ground plots of the Main Experiment (Roscher et al. 2004), which will be used for two treatments without soil history. From all four monoliths, the upper soil layer will be gently removed, and newly grown plant individuals, either gained from seed material from a supplier (without history) or collected from the selected plots of the former Trait-Based Experiment (with history). In the end, we will have the following four treatments in each EcoUnit: (1) ‘with plant history, with soil history’; (2) ‘without plant history, with soil history’; (3) ‘with plant history, without soil history’; and (4) ‘without plant history, without soil history’. The experiment will run for ~6 months before it gets destructively sampled.