Intensive management enhances mycorrhizal respiration but decreases free-living microbial respiration by affecting microbial abundance and community structure in Moso bamboo forest soils

Intensive management is known to markedly alter soil carbon (C) storage and turnover in Moso bamboo forests compared with extensive management. However, the effects of intensive management on soil respiration (R_S) components remain unclear. This study aimed to evaluate the changes in different R_S components (root, mycorrhizal, and free-living microorganism respiration) in Moso bamboo forests under extensive and intensive management practices. A 1-year in-situ microcosm experiment was conducted to quantify the R_S components in Moso bamboo forests under the two management practices using mesh screens of varying sizes. The results showed that the total R_S and its components exhibited similar seasonal variability between the two management practices. Compared with extensive management, intensive management significantly increased cumulative respiration from mycorrhizal fungi by 36.73%, while decreased cumulative respiration from free-living soil microorganisms by 8.97%. Moreover, the abundance of arbuscular mycorrhizal fungi (AMF) increased by 43.38%, but bacterial and fungal abundances decreased by 21.65% and 33.30%, respectively, under intensive management. Both management practices significantly changed the bacterial community composition, which could be mainly explained by soil pH and available potassium. Mycorrhizal fungi and intensive management affected the interrelationships between bacterial members. Structural equation modeling indicated that intensive management changed the cumulative R_S by elevating AMF abundance and lowering bacterial abundance. We concluded that intensive management reduced the microbial respiration-derived C loss, but increased mycorrhizal respiration-derived C loss.