Soil carbon, nitrogen, and phosphorus cycling microbial populations and their resistance to global change depend on C:N:P stoichiometry

Maintaining the stability of ecosystem functions to global
change calls for a better understanding the regulatory factors of
functionally specialized microbial-groups and their
population-response to disturbance. Here, we
explored this issue by collecting soils from 54
managed ecosystems in China and building a predictive model of
microcosm experiments. Soil carbon:nitrogen:phosphorus (C:N:P)
stoichiometry (35%~49%) imparted a greater individual
effects on the abundances of microbial-groups associated with
main carbon C, N, and P biogeochemical processes in
comparison with geographical
conditions (7%~10%). Soil total C and N
contents were significantly positively correlated with the
abundances of diazotrophs (nifH), nitrifiers (bacterial
amoA), nitrate reducers (narG) and
denitrifiers (nirS/K and nosZ genes). Soil
C:N ratio not only exhibited a negative relationship
with the abundances of P
activators (phoD, phoC and
pqqC genes), but also with
cellulolytic decomposers (fungcbhIR and
GH74 genes). Nitrogen cycling genes, including bacterial
amoA, nirS, narG and
norB, exhibited higher genetic resistance to N
deposition compared with the drying-wetting cycles and
warming. Soil total C, N and P contents, and their
ratios had a strong direct effect on the genetic
resistance of microbial-groups. Soil C:P ratio was selected by
random forest analyses as the main predictor of N cycling genetic
resistance to N deposition. Soil total C and N contents, and their ratios
were the main predictors of the P cycling genetic resistance to
three global change drivers. Overall, our
work highlights the importance of soil stoichiometric balance for
maintaining the ability of microbially-driven ecosystem functions to
withstand global change.