Three-source partitioning of soil respiration by 13C natural abundance and its variation with soil depth in a plantation

Partitioning soil respiration into three components is vital to identify CO₂ sink or source and can help us better understand soil carbon dynamics. However, knowledge about the influences of soil depth and the priming effect on soil respiration components under field has been limited. Three components of soil respiration (root respiration, rhizomicrobial respiration and basal respiration) in a plantation in the hilly area of the North China were separated by the ¹³C natural abundance method. The results showed that the average proportions of rhizomicrobial respiration, root respiration and basal respiration at the 25–65 cm depths were about 14, 23 and 63 %, respectively. Three components of soil respiration varied with soil depth, and root respiration was the main component of soil respiration in deeper soil. The priming effect was obvious for the deep soil respiration, especially at the 40–50 cm depth. Thus, depth and priming effect should be taken into account to increase the accuracy of estimations of soil carbon flux.