Establishment of native Eucalyptus pauciflora and exotic Eucalyptus nitens on former grazing land

摘要

The success of tree plantings in agricultural landscapes within dry and variable rainfall regions is often below expectations. The aims of this study were to investigate techniques for establishing a local native species (Eucalyptus pauciflora) and an exotic species (E. nitens) in the Midlands of Tasmania, a tree-denuded region that has been grazed for over 100 years in Australia. We established trials at the Sorrel Springs and Woodland Park properties. We compared six establishment techniques: control; understorey nurse planting; spot burn; mulch; tree-guard and; self-watering tree-guard. Three months, 1 and 6 years after planting we measured tree height, health index and mortality. At Sorrell Springs tree-guarded treatments had greater height than other treatments at year one, but there were no effects of treatment at year six on height, health or mortality. At Woodland Park mulch, burn and tree-guarded treatments had greater height 1 and 6 years after planting. At year six tree-guarded treatments had lower mortality than other treatments. At Sorrell Springs height of E. nitens was greater than E. pauciflora at year one but not at year six. At Woodland Park height of E. nitens was generally greater at year six but having almost double the incidence of mortality relative to E. pauciflora. We conclude that expensive tree-guarding is only warranted where high browse pressure is expected and that on such sites species with tough leaves that are resistant to browsing should be considered. Further that in environments marginal for growing trees, best practice establishment technique is generally as effective as additional treatments of understorey nurse planting, spot burning or mulching.