Stand ages regulate the response of soil respiration to temperature in a Larix principis-rupprechtii plantation

Understanding the linkage of soil respiration and its sensitivity to temperature with forest structure including stand age is critical for accurately assessing the impact of afforestation on global carbon balance. In this study, we investigated the changes of soil respiration (RS) and its components (soil heterotrophic (RH) and autotrophic (RA) respiration) in response to seasonal temperature change over three Larix principis-rupprechtii plantation stands (10-year-old sapling stand, 20-year-old young stand and 45-year-old mature stand) in North China. We found a significant seasonal variation of RS, RH and RA (P < 0.001), and significant stand age effect on RH (P = 0.004). Among the three age stands, sapling stand has the lowest RH during the snow-free season, possibly due to the lowest soil organic carbon. All three stands show that RS exponentially increases with increasing temperature, and the Q10 of RH (from 2.69 to 3.03) is significantly lower than that of RA (from 3.06 to 4.39). Furthermore, the Q10 of RH is significantly dependent on stand age. The Q10 of RH at mature stand (3.03 ± 0.09) was substantially higher than that at sapling stand (2.69 ± 0.08), highlighting the importance of stand age in regulating the response of soil respiration to temperature change. We also found that the transient turnover rate of soil organic carbon in sapling stand is significantly faster than those in young and mature stands (P < 0.001) due to the highest soil temperature at sapling stand. Such regulations of stand age on soil carbon cycling through abiotic factors must also be taken into account when investigating the effect of plantation on the global carbon cycle.