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Partitioning soil respiration in lower subtropical forests at different successional stages in southern China

Author(s): HAN Tian-Feng | ZHOU Guo-Yi | LI Yue-Lin | LIU Ju-Xiu | ZHANG De-Qiang

Journal: Chinese Journal of Plant Ecology
ISSN 1005-264X

Volume: 35;
Issue: 09;
Start page: 946;
Date: 2011;

Keywords: autotrophic respiration | forest succession | heterotrophic respiration | lower subtropical forest | Q10

Aims Quantifying forest soil respiration (RS) components is vital to accurately evaluate carbon sequestration of forest ecosystems. Our objectives were to determine (1) seasonal variations in RS and its components of autotrophic (RA) and heterotropic respiration (RH) in subtropical forests, (2) the relative contributions of RA and RH to RS in the three subtropical forests and (3) relationships between RS and temperature and water content.Methods We used the trenching-plot and infrared gas exchange analyzer approaches to determine RA and RH in the soil surface CO2 flux for monsoon evergreen broad-leaved forest (MEBF) and its early succession communities, coniferous and broad-leaved mixed forest (MF) and coniferous masson pine forest (MPF) in southern China. Rate of RS was measured twice a month in the hot, humid season (April-September) and once a month in the cool, dry season (October-March). Soil temperature and soil water content were measured at the same time.Important findings RS, RA and RH varied markedly during the year with high rates in the hot, humid season and low rates in the cool, dry season. RS rate measured in the trenched plots (RH) at these forests showed an increasing trend with succession, but the change was not statistically significant. RS and RA followed a similar seasonal trend and were highest in MEBF and lowest in MF. Contribution of RA to RS was (39.48±15.49)%, (33.29±17.19)% and (44.52±10.67)% in MPF, MF and MEBF, respectively. Repeated measurement ANOVA indicated that soil temperature was the main factor that affected RS and its components, and there was a significant exponential relationship between them. While there was no significant relationship between soil water content and soil respiration flux, there appears to be a mild inhibition phenomenon. Soil Q10 values increased with succession, whereas autotrophic respiration (RA) is more sensitive to temperature in all stands.
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