Rates of soil respiration components in response to inorganic and organic fertilizers in an intensively-managed Moso bamboo forest

• Inorganic (IF) and organic fertilizers (OF) increased R H , with greater role of OF. • Both IF and OF increased R A , with greater role of IF. • Q 10 value of R H was lower in the OF than in the IF treatment. • Increased R H was related to increased WSOC concentration and enzyme activity. • Increased R A was related to increased biomass and N concentration of fine roots. Fertilization is a common practice to increase forest productivity; however, the responses of soil respiration (R S ) components to the application of inorganic and organic fertilizers and the associated mechanisms are not clear in subtropical forest ecosystems. In this field trial conducted within an intensively-managed Moso bamboo ( Phyllostachys edulis ) forest, we aimed to compare the effects of inorganic and organic fertilizers, and their combination on seasonal variations in R S components, i.e., heterotrophic (R H ) and autotrophic (R A ) respiration, and to establish the relations of R S components with soil properties. Fertilizer additions increased R H ( P < 0.05), with the increase being greater with organic than with inorganic fertilizer. Fertilization also increased R A , but the effect was greater with inorganic fertilizer. Furthermore, fertilizer additions increased ( P < 0.05) the concentrations of water-soluble organic C (WSOC) and microbial biomass C, invertase and β-glucosidase activities, as well as the biomass and N concentration of fine roots. Irrespective of fertilizer treatment, strong seasonal patterns were observed in both R S and R H , and an exponential relation ( P < 0.01) was found between R S components (R H and R A ) and soil temperature. Additionally, the Q 10 for R H was higher ( P < 0.05) in the inorganic than the organic fertilizer treatment. Although R S and R H showed no correlation with soil moisture content in any treatment, each of them was positively correlated with WSOC concentration and activities of invertase and β-glucosidase ( P < 0.05). In the fertilized treatments, R A was positively related to β-glucosidase activities ( P < 0.05) but not to the concentrations of WSOC or microbial biomass C. In conclusion, soil R A and R H in the subtropical Moso bamboo forest responded differently to the application of inorganic and organic fertilizers, indicating that separation of total R S into soil R H and R A is critically necessary to predict R S in subtropical forests under different fertilizer regimes.