In order to understand the relationship between environmental change and terrestrial ecosystems, the Environmental Protection Administration is promoting a network of carbon dioxide flux monitoring station in Taiwan. The ChiLan flux monitoring station has operated since May, 2005. Fluxes of carbon dioxide, water vapor, and sensible heat fluxes over the forest canopy were measured by the eddy covariance method. A 3-D sonic anemometer and an open-path analyzer were mounted on top of a 24-meter instrument tower over a natural regenerated stand consists mainly of the tree species of Taiwan cypress (Chamecyparis obtuse var. formosna). Synchronized analog signals from the open-path analyzer and 3-D sonic anemometer were digitalized with sampling rates of 10~20 Hz. Located on a valley slope of 15o , the Chilan site is considered as steep slope site for the eddy covariance tower flux site. The site also is located in the cloud forest zone. Frequent fog and daily mountain-valley wind not only induce instrumentation difficulty but also compound the calculation of fluxes.

carbon dioxide flux, eddy covariance, long term ecological research