Sustainable harvest rates of ironwood, Erythrophleum chlorostachys, in the Northern Territory, Australia

Ironwood, Erythrophleum chlorostachys (F.Muell.) Baill., is harvested for timber in the Northern Territory. Available data on ironwood growth rates and stand structures were collated to help inform sustainable management. In 32 plots (0.1 ha each) within 300 km² of a widespread savanna vegetation type in the Northern Territory, ironwood trees represent ∼11% of the total basal area of all trees and 12% of all individual trees >3 m high. Nevertheless, the density of potentially harvestable trees with a diameter at breast height >35 cm is low at 150 km^-2, whereas the density of trees in the preferred size of >40 cm is only 30 km^-2. The slow growth rate means that the sustainable harvest is only 1.8 trees km^-2 year^-1. This represents a maximum estimate that does not account for the high rate of poorly formed boles and the lower density of ironwood throughout most of its range. Limited data on tree growth rates of isolated seedlings and coppice indicate that trees could reach harvestable sizes in decades instead of centuries if competition with other species is reduced; however, there has been no assessment of the relative wood quality of fast- and slow-growing ironwoods.