Patterns in plant-bacteria relationships
Plant richness only played a dominant role in the modularity in the plant-bacteria network, in contrast, SM was the key predictor for most of network parameters, the number of bacterial OTUs linked to each plant species (Fig S6).
The trend of the relationships in the plant-bacteria network was the opposite to that of the plant-fungi network: the trend in plant-bacteria links shows a greater number of bacterial OTUs linked to each plant species at lower levels of plant species richness (Fig 3a). Furthermore, the trend in the broader pool of total number of bacterial OTUs (in the whole soil community) plotted against plant species per site broadly paralleled this (Fig 3b).
In terms of the functional genes composition of bacterial OTUs in the network associated with the plants, carbon fixation, oxidative phosphorylation and methane metabolism were the dominant functional gene categories (Fig. S7b). While the proportion of functional genes in the plant-bacteria network that belong to low, middle, and high level of plant richness were similar.