Soil pH moderates the resistance and resilience of C and N cycling to transient and persistent stress

The resilience of microbial functions like carbon (C) and nitrogen (N) cycling to stress is likely heavily dependent on pH. Past research, however, has been limited laboratory manipulations or a pH gradient resulting from differences in soil mineralogy. In this study, soils were collected >50-year field trial where plots have maintained at 4.9, 6 7.1. We selected copper (Cu) heat represent persistent transient stresses, respectively. Changes C mineralization, ammonia oxidation, denitrification, gene (16S rRNA, nirK , nirS amoA ) abundance immediately measured after heat- (40 °C for 16 h) Cu- (500 μg Cu g −1 1 mg induced during subsequent recovery over 56 days, compared an unstressed control. Higher significantly increased mineralization (by 217 %), oxidation 617 the abundances 16S rRNA 77 976 %) nir S 997 %). Soil had significant ( P < 0.001) selection effect phylotypes bacterial communities ammonium oxidizing bacteria (AOB). Ammonia was 0.05) more resistant resilient both stresses 7.1 soil. low than 4.9. Correspondingly, distinct present these soils, indicating that composition triggered by adaptation tolerance central factor governing functional resilience. Denitrification high Cu, Similarly, genes greater higher Although directly affects but not stress, our results indicated neutral harboured N (persistent) (transient) stresses. • impacts underpinning communities. optimal varied. Neutral Microbial