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Abstract
A stem taper equation compatible to the volume equation was derived from the data of 172 trees sampled in the three plantations of Paraserianthes falcataria in Pare, East Java. The stem taper equation in this study was based on a conventional logarithmic volume equation, with the addition of one free parameter that minimized the standard errors of estimate to the observed diameter of stems at 1.0-m intervals. The derived equation was able to predict the stem taper of P. falcataria reasonably well, while it was not flexible enough to describe delicate changes of the taper in the upper portion of stem. The equation was able to predict bole length and the volume up to the top diameter 20 cm, the diameter size merchantable for sawn timber in Indonesia, with reasonable accuracy. An appropriate rotation age for sawn-timber production was found to be 8–9 years old, at which the mean annual increment of sawn timber would be maximized.
Acknowledgments
The authors greatly appreciate Sadhardjo and Ela for their support in collecting data from the felled trees of P. falcataria in Pare, Indonesia. Our thanks are also to Shigejiro Yoshida for his advice on the earlier version of the manuscript. This research was supported by “Global environment research fund” B-S21b by Ministry of Environment of Japan.