Dynamics of heat balance during growing season of broadleaved Korean pine forest in Changbai Mountains
长白山阔叶红松林生长季热量平衡变化特征

Based on the gradient measurement of microclimate factors, radiation and soil heat flux from late May to early October, 2001 and by the method of Bowen ratio-energy balance (BREB), this paper estimated the latent heat and sensible heat above the broadleaved Korean pine forest in Changbai Mountains. The energy storage of forest air and vegetative was calculated, and the seasonal variations of heat balance components of the forest were analyzed. The results showed that the net radiation of the forest and the solar radiation were linearly correlated. All the heat balance components had the similar characteristics of diurnal variation to the net radiation, showing curves positive at daytime and negative at night, and the terms ranged as net radiation > latent heat > sensible heat > storage. The time of keeping positive terms in a day became shorter from June to October as influenced by shinning time. The highest net radiation was in June and the lowest in October. The monthly averaged net radiation was 0-527 and 0-(-)121 W x m(-2), and the latent heat was 0-441 and 0-(-)81 W x m(-2) for day and night, respectively. Sensible heat was 0-80 and 0-(-)26 W x m(-2), and energy storage was 0-44 and 0-(-)26 W x m(-2) for day and night, respectively. The ratio of latent heat to net radiation at daytime decreased gradually from August to October, and the ratio of sensible heat and energy storage increased correspondingly. Especially 2-3 days after the first severe frost, a sudden drop of latent heat and a sudden bounce of sensible heat appeared. The instruments and measurement methods of heat flux were also concisely discussed in this paper.