Old-growth forests are primarily found in mountain ranges that are less favorable or accessible to land use. Consequently, there are fewer scientific studies on old-growth forests. By using eddy covariance approach, Prof. Zhang Yiping of XTBG and his research team examined the carbon balance of a 300-year-old subtropical evergreen broadleaved forest. The research indicated that the old-growth forest acted as a large carbon sink.

The study was carried out in the Ailao Mountain Nature Reserve (24°32′ N, 101°01′ E; 2476 m elevation) in Yunnan, SW China, where an old-growth subtropical evergreen broadleaved forest is spread widely and well protected. The researchers chose a forest having a stand age > 300years and free of management.

The post-QA/QC eddy covariance based carbon flux data indicates that a 300-year-old subtropical evergreen broadleaved forest acts as a large carbon sink of ∼ 9tC ha−1 yr−1 during their investigation interval. The researchers found that the larger trees continue to strongly sequester carbon in the studied forest, with about 60% of biomass increment in trees>60cm. In complex terrain and forest structure, biometric measurements simultaneous with eddy flux appear to be necessary.

The research has been published in Atmospheric Environment, 45 (8): 1548-1554.