Effect of establishment density on yield from eucalypt pulpwood plantations in southern Australia

Planting density remains a primary silvicultural decision influencing productivity and financial outcomes in eucalypt pulpwood plantations. Growth data from 20 Eucalyptus globulus and E. nitens planting-density experiments established in Western Australia, South Australia, Victoria and Tasmania were collated and analysed. Under-bark stem volume growth to age 10 years (range 50–450 m3 ha−1) was strongly correlated with site mean annual rainfall (range 500–1200 mm). On the higher-productivity sites (>270 m3 ha−1), greater established densities increased stand-level yield, whereas on lower-productivity sites (<170 m3 ha−1) density effects were modest and sometimes similar across the range 600–1200 stems ha−1. Mortality-related volume losses were relatively small and unrelated to density. Stem diameter distributions were strongly site productivity- and density-dependent, with consequences for harvesting productivity. There is a need for contemporary experiments using improved germplasm under second or subsequent rotation growing conditions, given changes in climate and operational practices.