Water level regulates the rhizosphere priming effect on SOM decomposition of peatland soil

The rhizosphere priming effect (RPE) is vital in soil organic matter turnover，but its role in peatlands remains unclear, especially when considering different water levels. In this study, we measured the CO 2 emission rate from rhizosphere and bulk soil of peatland at different water levels, together with isotope of 13 C, to evaluate the RPE in peatland. Results showed that the decomposition of SOM was significantly affect by RPE, and the RPE varied significantly among water levels ( p  < 0.05). Positive RPE was observed at −40 cm which soil CO 2 emission increased by 59%, with rate increased 0.04 g CO 2 pot −1 d −1. And negative RPE was observed at −20 cm and 0 cm, which soil CO 2 emission decreased by −92% and −83%, with rate decreased 2.01 and 1.94 g CO 2 pot −1 d −1, respectively. Positive RPE at −40 cm and negative RPE at −20 cm and 0 cm, suggested the RPE enhanced soil carbon accumulation at higher water level, and the RPE threat the carbon sink when water level further reduced. Our results showed that the RPE was a nonnegligible process in predicting peatlands carbon dynamic, especially with intensified climate change and peatlands degraded condition.