摘 要(英文)：tAtmospheric carbon dioxide (CO2) concentration and nitrogen (N) deposition may interactively impactsoil respiration in terrestrial ecosystems. However, the effects of elevated CO2and N deposition on soilrespiration are not fully understood especially in subtropical forest ecosystems in southern China whereambient N deposition is high. In this study, we investigated the seasonal responses of soil respiration toelevated CO2and N addition in young subtropical forest ecosystems in southern China using open-topchambers. Two CO2treatment levels (i.e., ambient CO2and 700 mol mol−1) and two N levels (i.e., ambientand 100 kg N ha−1yr−1) were considered. Forty-eight 1–2 years old seedlings (eight seedlings per each of6 species) were planted in each chamber. In the wet season, soil respiration significantly enhanced underelevated CO2and N addition with no interactive effect. There was not significant relationship betweentreatment-enhanced soil respiration and soil moisture in the wet season, suggesting that increases in soilrespiration resulted in large part from treatment-induced increases in tree growth and C inputs. In the dryseason, soil respiration significantly enhanced under elevated CO2, but did not significantly change underN addition. The N-induced change in soil respiration negatively corrected with soil moisture in the dryseason, indicating that decrease in soil moisture under N addition, together with increase in tree growthinteractively resulted in negligible net change in soil respiration. Our results highlighted the seasonalimportance of environmental controls under elevated CO2and N deposition in the assessment of soil Csequestration potential in subtropical forest ecosystems in southern China.
Seasonal responses of soil respiration to elevated CO2and N additionin young subtropical forest ecosystems in southern China