The field experiment was conducted at a Sphagnum-dominated open bog and an adjacent Sasa-dominated transition peatland in Sarobetsu Mire with the total area of 6658 ha, in which bog with flat lawn is the dominant peatland type , in northern Hokkaido Island, northern Japan. ,The mire was bordered by drainage ditches, a river and pastures. About 6-m-thick peat has accumulated for 4000–5000 years. ,The turbulent fluxes of sensible heat, latent heat were measured using the eddy covariance system.