Abstract. The formation and vertical distribution of sapwood and heartwood were studied with a 45-year-old Cryptomeria japonica D. Don. The tree was grown at a plantation with 1.5 m • 3.0 m spacing near Miao-Li, Taiwan and was felled on 27 February 1992. The thickness of sapwood and heartwood was expressed by a ring count and a linear measurement. The east-west (E-W) wood strips were collected from 0.3 m above ground upwards to the top of the tree at 2.5 m intervals. The sapwood thicknesses from the base to the 10.3 m tree level height are around 20-22 growth rings and 42-t-2 mm. At the top of the tree, the sapwood thickness is narrower. The heartwood, which decreases in thickness with increasing tree level heights is not found at the top of the tree. The heartwood appears as a conical shape in the tree trunk. There is no statistical difference in sapwood/heartwood thickness between E-W aspects. Tree level heights and the tree level age were found to be important parameters in determining the thickness of sapwood/heartwood.

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