Study site and experimental design
We initiated this study in 2016, in a glasshouse and in large mesocosm
pots set in a fallow field on the Lincoln University campus (Lincoln,
New Zealand. 43.6434o S, 172.4678oE, elevation 10 m), and completed it in 2019 (Waller et al.2020). We designed 20 communities, each containing eight unique plant
species taken from a pool of 39 species (species details listed in Table
S1), and grown in 125 L pots (575 mm dia.). Full methods are described
in Waller et al. (2020), but briefly summarized here. Communities
varied orthogonally in their proportion of exotic plant species (0, 25,
50, 75, 100%) and woody plant species (0, 25, 38, 63%). Each of the 20
plant communities was replicated four times (80 pots total) and received
one of two soil treatments, described below. We included an additional
80 pots with a treatment with addition of herbivores (reported in Walleret al. 2020 and Allen et al. 2021). However, that
treatment was not relevant for our hypotheses, so is excluded from the
current analysis.