Eddy covariance measurements of CO₂ were taken for five years above six forests distributed from the northern to southernmost main islands of Japan. These forests included cool- and warm-temperate deciduous and coniferous forests. The climate of Japan is characterized by apparent seasonal changes and adequate precipitation affected by the East Asian monsoon. In this report, we compared net ecosystem production (NEP) among forests using the eddy covariance method and analyzed the climatic factors that affect seasonal and inter-annual changes in NEP in relation to forest type. The observed annual NEP from 2000 to 2002 ranged from 286 to 566 gCm^-2yr^-1, and this basically increased with decreasing latitude. The observed maximum 10 days mean NEP was about 1.5 times larger in the deciduous sites, although the growing period was more than 2 times longer in the coniferous sites.

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