Path analysis of relationships between conditioning and responding
plant communities mediated via soil abiotic and biotic parameters
Dissimilarity matrices were calculated between all samples. We used
Bray-Curtis dissimilarity for plants, fungi and bacteria with above
described transformations, and Euclidean distance for the abiotic
parameters using the ‘vegan ’ package (R Core Team 2018; Oksanenet al. 2018). For plant communities, all plant species present in
less than three samples were removed prior to analysis in order to
diminish the effect of rare plant species. Dissimilarity matrices during
conditioning and responding phases were calculated separately. Mantel
tests were carried out to explore the correlations between the distance
matrices using Pearson’s correlation coefficients with 999 permutations
using a Monte-Carlo permutation test to test the a prioriassumptions that conditioning plants will change soil communities (e.g.,
Heinen et al. 2018; Morrien et al. 2017) and abiotic
conditions (e.g., Bezemer et al. 2006; Zhang, Van der Putten &
Veen, 2016), and that this in turn alters the performance of responding
plant communities (plant-soil feedback, Ehrenfeld et al. 2005;
Van der Putten et al. 2013). We created a model that reflects
these pathways separately (Figure 3), to visualize how the conditioning
plant community affects the responding plant community.