The contribution of root respiration to soil CO2 efflux in Puccinellia tenuiflora dominated community in a semi-arid meadow steppe

Rising atmospheric CO2 and temperature are altering ecosystem carbon cycling. Grasslands play an important role in regional climate change and global carbon cycle. Below-ground processes play a key role in the grassland carbon cycle because they regulate …

The contribution of root respiration to soil CO2 efflux in Puccinellia tenuiflora dominated community in a semi-arid meadow steppe

In this study, the linear regression between soil respiration rate and root biomass was adopted to estimate the contribution of root respiration to total soil respiration in Puccinellia tenuiflora dominated community of a semi-arid meadow steppe in northeast China. The soil respiration rate reached the maximum value 2.45 μmol·m⁻²·s⁻¹ in late June and the minimum value 0.39 μmol·m⁻²·s⁻¹ in late September. Soil temperature is the major environmental factor controlling the seasonal variation of soil respiration. The root biomass ranged from 0.54 to 0.97 kg·m⁻², showing insignificant seasonal variation. Microbial biomass C reached the maximum value 0.50 g·m⁻² in mid August, presenting the least within-site variation. The pattern of seasonal change in root respiration rate was different from that in microbial respiration. Root respiration rate ranged from 0.19 μmol·m⁻²·s⁻¹ in May, to the maximum value 1.39 μmol·m⁻²·s⁻¹ in late June, then down to 0.28 μmol·m⁻²·s⁻¹ in late September; whereas, microbial respiration rate ranged from 0.61 μmol·m⁻²·s⁻¹ in May, to the maximum value 1.27 μmol·m⁻²·s⁻¹ in July, then down to 0.11 μmol·m⁻²·s⁻¹ in late September. There was a significant exponential correlation between microbial respiration rate and soil temperature, whereas not so for root respiration rate. We estimated that the contribution of root respiration to total soil respiration ranged within 24%–57% in spring and summer, and increased to 73% in autumn.