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An old-growth subtropical Asian evergreen forest as a large carbon sink

Tan, Zheng-Hong, Zhang, Yi-Ping, Schaefer, Douglas, Yu, Gui-Rui, Liang, Naishen, Song, Qing-Hai
Atmospheric environment 2011 v.45 no.8 pp. 1548-1554
atmospheric chemistry, biomass, broadleaved evergreens, carbon, carbon sequestration, carbon sinks, deciduous forests, ecosystems, eddy covariance, land use, old-growth forests, quality control, temperature, trees
Old-growth forests are primarily found in mountain ranges that are less favorable or accessible for land use. Consequently, there are fewer scientific studies on old-growth forests. The eddy covariance method has been widely used as an alternative approach to studying an ecosystem’s carbon balance, but only a few eddy flux sites are located in old-growth forest. This fact will hinder our ability to test hypotheses such as whether or not old-growth forests are carbon neutral. The eddy covariance approach was used to examine the carbon balance of a 300-year-old subtropical evergreen broadleaved forest that is located in the center of the largest subtropical land area in the world. The post-QA/QC (quality assurance and control) eddy covariance based NEP was ∼ 9tC ha⁻¹ yr⁻¹, which suggested that this forest acts as a large carbon sink. The inventory data within the footprint of the eddy flux show that ∼6tC ha⁻¹ yr⁻¹ was contributed by biomass and necromass. The large-and-old trees sequestered carbon. Approximately 60% of the biomass increment is contributed by the growth of large trees (DBH>60cm). The high-altitude-induced low temperature and the high diffusion-irradiation ratio caused by cloudiness were suggested as two reasons for the large carbon sink in the forest we studied. To analyze the complex structure and terrain of this old-growth forest, this study suggested that biometric measurements carried out simultaneously with eddy flux measurements were necessary.