Seasonal dynamics of fine root respiration in the degraded and successional primary Korean pine forests in the Lesser Khingan mountains of Northern China

Abstract The broad-leaved and Korean pine mixed forests in the Liangshui National Natural Reserve, China, are important components of boreal forests in areas that are sensitive to global climate change. Respiration rates of excised roots were measured using an oxygen electrode (Hansatech Oxy-Lab 2, UK) to examine the variation in and identify the controlling factors of fine root respiration (Rr) during the growing period (May–October) in 2016. The relationships between Rr and biotic/abiotic factors [e.g., soil temperature, live fine root biomass (LFRB), and the soil carbon index] were subsequently analyzed. The results showed that Rr was significantly higher in the secondary broad-leaved forest (SF) than that in the primary Korean pine forest (PK) ( p p   0.05). Rr tended to exponentially increase with soil temperature ( p 10 value of the PK was significantly higher than that of the SF ( p p p 2  = 0.75). The findings of the present study offer insights into the variability of the soil carbon sink function in the degraded and successional primary Korean pine forests.