Experimental design. (Right panel) One forest patch (four spatially independent patches in total) with invasion fronts of epigeic earthworms (orange) and endogeic and anecic earthworms (yellow) present. Three transects à 15 observation plots (1 x 1 m; Eisenhauer et al. 2007) will be established. In the area without earthworms, a field experiment will be set up with experimental plots (Left panel), five treatments, and six replicates. PVC shields will be used to establish earthworm enclosures of 1 x 1 m (Eisenhauer et al. 2009b). Phytometers will be planted in all observational and experimental plots (Eisenhauer et al. 2009b). In addition, intact soil cores will be taken and brought to the lab for seed addition experiments (Whitfeld et al. 2014).