| Abstrakt: |
SummaryThis case study is based on the growth of a 10-y-old plantation at Bairnsdale in Victoria's East Gippsland. The site is owned by the local water management authority. East Gippsland Water, and contains both a dryland blue gum (Eucalyptus globulus) plantation and an irrigated agroforestry trial using municipal wastewater.The irrigated agroforestry trial consists of three eucalypt species watered by two different sprinkler systems. The set-up costs and the relatively poor recorded growth suggest that this is a very expensive way to grow sawlogs. Observations and growth measurements indicate that spotted gum (Corymbia maculata) is a far better agroforestry species than either Sydney blue gum (E. saligna) or southern mahogany (E. botryoides.) From an agricultural viewpoint, this agroforestry trial has provided good shelter and feed for a successful beef cattle venture. Without data to quantify its effect on agricultural productivity, it is difficult to evaluate the trial's overall success.The dryland blue gum plantation has recorded moderate to poor growth. This result, however, must be viewed in the context of the area receiving 17% less than the long-term average annual rainfall since the plantation was established in 1996. Any continuation of this trend, as forecast by CSIRO predictions of global warming, has potential to further reduce the long-term suitability of what was already a marginal site for this species. The results suggest that it may be wise to limit future blue gum sawlog plantations in this area to sites with long-term rainfall averages of at least 800 mm y−1, and to plant more drought-tolerant species such as sugar gum (E. cladocalyx) or spotted gum in the 600–800 mm rainfall zone. |
