Journal of Tropical Ecology

The age of tropical rain-forest canopy species, Borneo ironwood (Eusideroxylon zwageri), determined by 14C dating

Hiroko Kurokawa a1c1p1, Toshiya Yoshida a2, Toshio Nakamura a3, Julaihi Lai a4 and Tohru Nakashizuka a1
a1 Center for Ecological Research, Kyoto University and Dating and Materials Research Center, Nagoya University, Japan
a2 Uryu Experimental Forest, Hokkaido University, Uryu, Hokkaido 074-0741, Japan
a3 Dating and Materials Research Center, Nagoya University, Nagoya, Aichi 464-8602, Japan
a4 Forest Research Centre, Kuching, Sarawak, Malaysia


Using 14C dating, the life span and growth rate of Borneo ironwood (Eusideroxylon zwageri, Lauraceae), which is a canopy tree species with extremely durable and decay-resistant wood distributed in tropical rain forests of South-East Asia, were studied. Timber segments collected from 15 logged stumps in Kubah National Park, Sarawak, Malaysia, were analysed by accelerator mass spectrometry and the obtained data were calibrated to determine the age of individuals. The 14C dating turned out to be an effective method for estimating ages of long-lived trees, such as E. zwageri, in the aseasonal tropics because the estimated error was small compared with estimated age. We found that E. zwageri can live more than 1000 y and that the growth rate of this species was very slow, with a mean radial growth rate of 0·058 cm y-1. The life span was much greater and the growth rate was much slower than those observed or estimated for trees of Dipterocarpaceae, the dominant family in this tropical forest. The long life span of this species may be caused by wood durability with a high specific gravity and abundant defensive compounds. Given equal carbon allocation, the high density and carbon-based defensive compounds may result in a reduced growth rate.

(Accepted December 8 2001)

Key Words: Borneo ironwood; 14C dating; life history; long-lived tree; tree age; tropical rain forest.

c1 Corresponding author. Present address: 509Ð3, Otsuka, Kamitanakami-Hirano, Otsu, Shiga 520-2113, Japan. Email:
p1 Current address: Research Institute for Humanity and Nature, Kyoto 602-0878, Japan.