The magnitude and direction of priming were driven by soil moisture and temperature in a temperate forest soil of China

Abstract

Increased temperature and extreme precipitation due to global climate change play a critical role in the soil carbon cycle. The priming effect describes the changes in soil organic carbon (SOC) mineralization after fresh organic matter (FOM) inputs and is a major component of the soil carbon cycle. However, further research is needed to improve understanding of the interactive influence of warming and soil moisture changes on soil carbon priming. In this study, we conducted a 57-day incubation experiment to investigate the interactive effects of soil moisture and temperature on priming on forest soils from a temperate region of China. 13C labeled Glucose was added to simulate the priming effect induced by rhizosphere exudates at three soil moisture levels (20 %, 55 %, and 90 % of field capacity (FC)) and three temperature levels (5, 15, and 25 °C). Soil priming increased significantly with the increase of moisture; the cumulative priming effects were positive at 55 % and 90 % FC, but were negative at 20 % FC. Warming significantly stimulated the magnitude of priming at all moisture levels, with the greatest negative priming under 20 %FC×25 °C (−165.9 mg C kg−1) and the greatest positive priming under 90 %FC×25 °C (588.0 mg C kg−1). Furthermore, priming considerably influenced the soil carbon balance, which resulted in maximum carbon storage under 20 %FC×25 °C (279.4 mg C kg−1) and the greatest carbon loss under 90 %FC×25 °C (−493.9 mg C kg−1). Furthermore, temperature sensitivity (Q10) of SOC mineralization was highly dependent on FOM inputs. In unprimed soils, Q10 was negatively and significantly related to moisture; however, no significant correlation was observed between Q10 and moisture after glucose addition because of the priming. The findings of this study contribute to the better understanding of the temperate forest soil carbon cycle under global climate change by highlighting the interactive effects of soil moisture and temperature on the priming effect.