Transpiration of a Cryptomeria japonica plantation in winter : analysis based on one-year sap flow measurements

Cryptomeria japonica plantations, a type of coniferous evergreen forest, are one of the most common forest types in Japan. It is critical to clarify the differences between the forest water cycle of C. japonica plantations and that of broad-leaved deciduous forests because as many C. japonica plantations in Japan have been converted from broad-leaved deciduous forests. This study examined the significance of the transpiration of a C. japonica plantation in winter using one-year heat pulse velocity (HPV) data. HPV would be linearly related to the canopy transpiration rate and was higher in summer than in winter, with a maximum in August. In January and February, March and April, and December, HPV was approximately 20, 70, and 40% of that in August, respectively. The relatively high HPV in March and April indicated that the forest water cycle of the C. japonica plantation during these months was quite different from that of broad-leaved deciduous forests in the same region in terms of transpiration