Individual- and stand-level stem CO2 efflux in a subtropical Schima superba plantation

[摘要] Stem respiration is an important, but poorly studied component of totalforest ecosystem respiration. Stem CO₂ efflux was investigated with anopen gas exchange system while stand microclimate and stem temperature werecontinuously monitored in a Schima superba plantation in South China for several days inAugust and December 2010. The temperature response of respiration in thedifferent seasons, the vertical variation in stem CO₂ efflux along thestem, and the stand-level stem CO₂ efflux were examined. Stem volume wasidentified as the better correlate for stem CO₂ efflux and was used asthe scalar for the stand-level estimates of stem CO₂ efflux in this S. superbaplantation. Volume-based stem CO₂ efflux was higher at 2 m than at 1.3 m.Mean stem CO₂ efflux was 268.9 and 104.6 μmol m⁻³ s⁻¹in August and December, respectively, indicating a dramatic seasonalvariation of stem CO₂ efflux. The temperature response of stem CO₂efflux remained constant during our study period with Q₁₀ values of 1.9and 1.8. In this subtropical S. superba plantation, stem CO₂ efflux per unitground area averaged 3.36 and 1.26 μmol m⁻² s⁻¹ based on themeasurement data at 1.3-m height of the stem in August and December,respectively. Our results suggest that stem CO₂ efflux has a constanttemperature response, and the seasonal variation in stem CO₂ efflux ismainly controlled by stem temperature, and the vertical variation in stemCO₂ efflux needs to be considered in the stand-level estimation.

[学科分类] 地球化学与岩石