Abstract :
Three Acacia species native to northern Australia and adjacent regions of Papua New Guinea and eastern Indonesia have attained prominence for short-rotation plantation forestry in the humid tropics. Plantation areas of Acacia auriculiformis and A. mangium expanded from 1970s, while A. crassicarpa planting commenced in the 1990s, after species trials showed it could outperform the first two species on certain site types such as peat soils and seasonally flooded sandy soils. Research into reproductive biology and propagation methods laid the foundation for expansion of clonal Acacia hybrid (A. mangium × auriculiformis) plantations, most notably in Vietnam, where over250 000 ha of hybrid plantations are now established. Well-managed and appropriately- sited Acacia plantations in Indonesia and Vietnam display rapid growth rates, with mean wood annual increments exceeding 30 m3 ha-1 over six-year rotations in some cases. Altogether, in the humid lowland tropics of south and South-East Asia there are now over 2 Mha of plantations of these Acacia species. Over half of this area has been established on grasslands, degraded scrublands or land previously planted with other tree or crop species, but substantial clearing of natural forests for plantation establishment has also taken place. In hindsight, the latter will be seen by many as a poor landuse decision.
