GROWTH CHARACTERISTICS AND BIOMASS ACCUMULATIONS OF <em>ACACIA</em> <em>MANGIUM</em> UNDER DIFFERENT MANAGEMENT PRACTICES IN INDONESIA

Abstract

HERIANSYAH, I., MIYAKUNI, K., KATO, T., KIYONO, Y. & KANAZAWA, Y. 2007. Growth characteristics
and biomass accumulations of Acacia mangium under different management practices in Indonesia. Tree
biomass accumulations and age-related changes of Acacia mangium plantations were determined using a
destructive sampling technique. These data were used to estimate optimum harvesting time. Tree biomass
samples were collected in 3-, 5-, 8- and 10-year-old plantations in West Java, and in 2.5-, 5.5-, 8.5- and 10.5-yearold
plantations in South Sumatra. About 15 trees were sampled from each stand. Tree growth characteristics
were evaluated for both sites. Specific wood density in unthinned plantation was higher than in thinned
plantation. Proportion of stem biomass in thinned plantation was constant during thinning period and
thereafter slightly increased with age, whereas leaf biomass decreased. In unthinned plantation, proportion
of stem biomass increased with age, while leaf biomass drastically decreased when competition occurred in
the young stage but became relatively constant thereafter. Allometric equations were developed for each site
to estimate root, stem, branch, leaf, aboveground and total biomass and stem volume. Using these equations,
the stem volume and biomass of each component for each stand age were estimated. A single allometric
relationship for all sites was found just for estimation of root biomass and stem volume. Therefore, the use
of site-specific equation is recommended. According to the optimum productivity values, longer rotation
is available to enhance wood quality and wood utilization for thinned plantation in West Java. A rotation
of six and eight years is recommended to maximize biomass accumulation and benefits respectively for
unthinned plantation in South Sumatra.