A review of ecophysiologically-based seedling specifications for temperate Australian eucalypt plantations

Abstract

The Australian hardwood plantation estate has significantly expanded in the last decade. Key production issues included: (1) will Eucalyptus nitens Maiden seedlings produced in nurseries on relatively mild sites be susceptible to transplant shock and browsing on cold out-planting sites and can this be managed? And; (2) what specifications should be required of nursery producers for Eucalyptus globulus Labill seedlings for out-planting on mild ex-pasture sites? This review outlines the research conducted in order to address these key questions. Nitrogen deprivation in the nursery induced accumulation of foliar anthocyanin which conferred hardiness to low temperature. Target specifications of 8–10 g/kg foliar nitrogen are recommended. Height of >120 mm, root collar diameter >2.8 mm, seedling container volume of ≥85 cm3, depth of ≥73 mm, density of ≥549 cells/m2 and foliar nitrogen concentration of 15–20 g/kg were found to be key specifications for optimal E. globulus growth following planting onto mild ex-pasture sites. Exponential nutrient loading was a useful technique for attaining target foliar N concentrations. Seedling size was found not to affect growth of E. globulus post-planting on mild ex-pasture sites. However, large seedlings were preferentially browsed on high vertebrate-browse-pressure sites in Tasmania (poisons are banned and shooting is not effective on some sites) that did not affect subsequent growth rate but did increase the incidence of double-leaders. The ‘target seedling concept’ is applicable to eucalypts for Australian planting sites: specifications attained in the nursery should be matched to the factors limiting growth on the planting sites.