Soil respiration and carbon balance in a Moso bamboo (Phyllostachys heterocycla (Carr.) Mitford cv. Pubescens) forest in subtropical China

Understanding spatial and temporal variation in soil respiration (RS) in different forest ecosystems is crucial to estimate the global carbon balance. Bamboo forest is a special forest type in southern China covering an area of 5.38 million ha, 70% of which are Moso bamboo (Phyllostachys heterocycla (Carr.) Mitford cv. Pubescens) forests. Bamboo forests contribute more than 10% to the whole carbon stock of forest ecosystems in China, and therefore play a critical role in the regional and national carbon balance. However, little information on the seasonal dynamic of RS and the carbon balance of Moso bamboo forests is available. In this study, litter removal and trenching methods were applied to partition RS into root respiration (RR), litter respiration (RL) and soil organic matter derived respiration (RM), and to study their seasonal dynamics and carbon balance in a pure Moso bamboo forest. Monthly RS, its source components and combined monthly environmental factors were measured. RS and its source components showed a significant seasonal variability with higher values from June to August and lower values from December to February driven by soil temperature and moisture (P < 0.001). Annual average RS, RR, RL and RM were 2.37, 0.69, 0.58 and 1.10 mu mol m(-2) s(-1) with Q10 values of 1.25, 1.15, 1.19 and 1.26, respectively. Annual RS was 8.97 t C ha(-1), and RR, RL and RM contributed 29%, 22% and 49%, respectively. Annual NEP was 4.72 t C ha(-1) y(-1), indicating that the Moso bamboo forest studied is a significant carbon sink.