This study evaluated heat storage flux or released flux due to biotic activity (SC) in forests. First, as a case study, we investigated diurnal pattern of SC over an evergreen coniferous forest via a three-year continuous eddy-cov riance CO2 flux measurement. We clarified that (1) in some case, SC reached over 15% of total heat storage flux during the snow-free period (May-October), (2) SC was 4.3 W m-2 on average and reached 4.9-7.0% of average sensible and latent heat fluxes during the snow-free period. Second, we estimated SC by using net ecosystem exchange over several forest ecosystems as reported by previous studies. During the snow-free period over several forest ecosystems, the maximum SC and daily amplitude exceed 3-12 and 4-17 W m-2 respectively. Those values were comparable to those of the latent heat storage flux in the air layer from the ground surface to the level of eddy-covariance measurement over several forest ecosystems as shown by previous reports. Our findings suggest that SC cannot be always ignored. We would need to examine whether SC can be ignored based on the circumstances of the targeted research.
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