PARENT SESSION
Posters P5D Emerging techniques and systems. Abstracts (731-741)

A multichannel automated chamber system for continuous measurement of forest canopy photosynthesis. Naishen Liang^*,1, Yasumi Fujinuma¹, Gen Inoue¹, ¹ CGER, National Institute for Environmental Studies, Tsukuba, Ibaraki, Japan

ABSTRACT- Our purpose is to scale up the canopy level photosynthesis by utilizing measurements of leaf/shoot level photosynthesis, canopy architecture and models of irradiative transfer. We developed a fast-response system with 24 chambers that connected in parallel to a single CO2 analyzer equipped with a 24-channel gas sampler to sequentially measure photosynthesis. The cylinder design chambers can completely envelop a segment of branch with several twigs for coniferous species. Between measurements the chamber is opened to allow wind to pass through the chamber and prevent temperature increase inside the chamber. During the measurement, the chamber is closed and the change in CO2 concentration inside the chamber is measured. The sampling period for each chamber is set to be 150 s, and running a measurement cycle through 24 chambers takes just 1 h. In August 2003, the automated system was installed to a 45-year-old larch forest, Hokkaido, Japan. Ten trees around a canopy scaffold were sampled for measurement of canopy photosynthesis, with twelve chamber in the sunlit portion, eight chambers in the mid-crown, and four chambers in the lower portion. Furthermore, understorey gas exchange was also measured continuously by another multichannel automated chamber (90 * 90 * 50 cm, L * W * H) system. The contribution of photosynthesis to net ecosystem exchange (NEE) will be discussed in this presentation.

KEY WORDS: Photosynthesis, Temperature, Automated chamber, PPFD