FIG 4.

Microbial communities were largely structured by stochastic processes across all soil wetting ages. (A) Contribution of stochastic and deterministic processes to microbial community composition based on Sørenson dissimilarity, which records presence-absence dissimilarities. We calculated the average variance component for each site. Thick lines show a LOWESS regression against NO₃- concentrations. Thin lines show 1,000 bootstrapped LOWESS regressions. (B) Contribution of stochastic and deterministic processes to microbial community composition based on Bray-Curtis dissimilarities, which record relative abundance dissimilarities. In all simulations, phylum richness was held fixed at the observed level for each site. Thick lines show a LOWESS regression against NO₃- concentrations. Thin lines show 1,000 bootstrapped LOWESS regressions.