Soil microbial community and associated functions response to salt stresses: Resistance and resilience.

Soil microbial communities and related ecological functions are influenced by salinization, but their resistance and resilience to different salinity stresses are still not well-understood. In this study, we investigated the changes in bacterial community and associated ecological functions under different NaCl and Na₂SO₄ stresses, and their resilience after removal of the stresses. The alpha diversity of bacterial community significantly increased under the slight to strong stresses of NaCl and Na₂SO₄ compared with the control, but no significant differences were observed at the end of the recovery period. The structures of bacterial community distinctly altered under the stresses of NaCl and Na₂SO₄ because they affected different salinity-tolerant microbiota. After the elimination of salt stresses, the bacterial community structures could not recover to their original states, and shifted to alternative states. NaCl and Na₂SO₄ stresses reduced the complexity and stability of bacterial co-occurrence network in comparison with the control. The bacterial co-occurrence networks became more complex and stable when salt stresses were removed. The accumulative CO₂ and N₂O emissions reduced under the slight to extreme stresses of NaCl and Na₂SO₄, but NaCl stress exhibited a greater suppression than Na₂SO₄. In the recovery period, the cumulative CO₂ and N₂O emissions were lower than those in the stress period, but CO₂ and N₂O emissions fluxes approached to those in the control at the end of stress period. The findings can provide implications for the management and reclamation of salt-affected farmland.