Soil CO₂ flux dynamics in the two main plantation forest types in subtropical China.

Chinese Fir and Moso bamboo are the two most important forest plantation species in subtropical China. However, information on greenhouse gas emissions from these forests is still scarce. A field study was carried out to compare soil CO(2) flux dynamics in Chinese Fir and Moso bamboo forests over a 12-month period using the LI-8100 Soil CO(2) Flux System. The soil CO(2) flux in both forest types showed similar daily and seasonal dynamic patterns with the highest soil CO(2) efflux at 14:00-16:00 in summer and the lowest in winter. Moso bamboo forest showed significant higher (P<0.01) annual mean soil CO(2) fluxes (52.9 t CO(2)ha(-1)yr(-1)) than Chinese fir forest (27.9 t CO(2)ha(-1)yr(-1)). The large difference in soil CO(2) fluxes may potentially influence the carbon cycle of the two forest types at the ecosystem scale. The CO(2) flux from the soil showed a significant positive correlation (P<0.0001) with soil temperature at 5 cm depth, a significant negative correlation (P<0.01) with air relative humidity, and no significant correlation with soil moisture in either forest types. The Q(10) value of soil respiration was higher in Chinese fir than Moso bamboo forest, indicating that soil respiration under Chinese fir forest will be more sensitive to temperature change. This study contributes to better understanding of the role Moso bamboo and Chinese fir forests may play in carbon cycle and global warming mitigation.