Influences of seedling size, container type and mammal browsing on the establishment of Eucalyptus globulus in plantation forestry

Abstract

Rapid early growth of tree seedlings is critical to the success of plantation establishment. We investigated the effects of seedling size (small and large) and container types (small [Lannen 121], medium [Lannen 81] and large [Forestry Tube]) in the nursery and the effects of mammal browsing after planting on growth of Eucalyptus globulus in Tasmania’s Southern Forests. After planting, seedlings were either exposed to browsing or protected from browsing by wire-mesh cages until age 6 months. Low browsing pressure resulted in around 20% and 5–10% of foliage being browsed in the large and small size categories, respectively, between 1 and 3 months after planting the uncaged treatment. 6 months after planting, height growth increment was lower, and 4 years after planting, mortality was higher in uncaged large than caged large seedling treatments. Six and twelve months after planting, seedlings raised in Forestry Tube containers had significantly greater height increment and root collar diameter relative to other treatments. By 4 years after planting, trees of the small seedling treatment had significantly greater diameter than those of the large seedling treatment, but there was no effect of container type treatment. Four years after planting there was no effect on diameter growth by browsing of <30% of foliage up to 3 months after planting, although there was greater incidence of double leaders in trees that had been browsed as seedlings. Small seedlings produced more growth 4 years after planting than large seedlings of E. globulus.