Role of microbial communities in conferring resistance and resilience of soil carbon and nitrogen cycling following contrasting stresses

Resilience of soil functions to transient and persistent stresses is improved more by residue incorporation than the activity of earthworms

“…Necromass, such as dead microbial cells induced by the heat stress, also provides a rapidly mineralised substrate that is easily accessible to free-living microorganisms (Drigo et al, 2012). A previous study has demonstrated that bacterial communities could recover to its original structure from a transient heat stress, but not from a persistent Cu stress (Shu, 2018). Routine successional trajectories of microbial communities may be altered differently by different stresses (de Vries and Shade, 2013), and gradual shifts of microbial community may be the result of long-term adaptations to the persistent Cu stress.…”

“…(1) Resistance was defined as the stability measured at day 1 after perturbation (Equation 2), while resilience was estimated as the integrative stability after day 1 up to 28 days following stress (Equation 3) (Shu, 2018). (2)…”

“…From each plot, three surface soil samples (0-20 cm depth) approximately 10 kg in weight were randomly sampled and mixed thoroughly. The soil had a pH (H 2 O) of 8.25 and contained 5.86 g C kg -1 and 0.71 g N kg -1 soil (Shu, 2018). Soil microbial biomass carbon (MBC) was analysed by chloroform fumigation (Vance et al, 1987).…”

“…Subsamples were taken for the analysis of microbial functions at intervals of 1, 3, 7, 14 and 28 days after the stresses were imposed. C mineralization was measured by the emission of CO 2 after 24 hours following the addition of 120 µl of organic C compounds which provides 50 mg C ml -1 and 9.72 mg N ml -1 to a 2 g of soil (Shu, 2018). Ammonia oxidation was determined by the chlorate inhibition method (Groffman 1985).…”

“…Ammonia oxidation was determined by the chlorate inhibition method (Groffman 1985). Potential denitrification was determined following anaerobic incubation of 20 g soil in the presence of 10% (v/v) acetylene (Shu, 2018).…”