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 CO2 emission rate from rhizosphere and bulk soil of peatland at different water levels, together with isotope of C-13, 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 CO2 emission increased by 59%, with rate increased 0.04 g CO2 pot(- 1) d(-1). And negative RPE was observed at-20 cm and 0 cm, which soil CO2 emission decreased by-92% and-83%, with rate decreased 2.01 and 1.94 g CO2 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.

Automated summary

This study evaluated the role of the rhizosphere priming effect (RPE) in peatlands by measuring the CO2 emission rate and isotope of C-13 in different water levels. The results showed that RPE significantly affected the decomposition of soil organic matter and varied among water levels. Positive RPE was observed at higher water levels, enhancing soil carbon accumulation, while negative RPE was observed at lower water levels, threatening the carbon sink.