Establishing a Eucalyptus plantation for koala food
O’Callaghan, P 1995, Lone Pine Koala Sanctuary.
To be self-sufficient in providing food for koalas, Lone Pine Koala Sanctuary established two plantation sites in 1988 and 1989. From a process of trial and error, plantation managers developed principles for best practice in establishing, maintaining and utilising Eucalyptus plantations.
There are eight factors to consider when establishing and utilising a koala food plantation:
- Site selection: The site should be characterised by an alluvial or podzolic soil type to cater to a wide range of flora species and support rapid growth, and should have reliable water availability.
- Planting density: For the plantation to be self-sufficient, 1000 trees must be planted per koala at a density of 1000 trees per hectare. At a planting density of 2 metres between trees, branches can develop to a suitable size and the time between harvesting is optimised.
- Ground preparation and mounding: Existing vegetation at the site must be managed before planting to favour the growth of the planted stock. To support root development, the site where each tree will be planted should be deep-ripped to 60cm.
- Species selection: The location of the plantation, its soil type, and the requirements of the koala colony will inform the species selected for planting. The planting of at least seven species is recommended for variation in diet.
- Planting: Planting should occur at the beginning of spring to support seedling establishment. Seedlings should be removed from pots and receive water immediately after planting, and then daily for 1-2 weeks. The immediate area surrounding each seedling should be mulched to reduce soil surface temperature and retain moisture around the tree.
- Irrigation and fertilisation: An irrigation system is necessary to supplement natural water supply and ensure the production of quality foliage throughout the year. A fertiliser that supplements soil nutrients will improve its overall quality and aid in leaf production.
- Weed and insect control: To support seedling growth, vegetation within one metre of the plant should be cleared via manual removal, chemical control or weed mats. Pest insects should be chemically controlled; however, trials must be performed to ensure the chemical does not detriment leaf quality or palatability.
- Harvesting techniques: Branches can be harvested using pruners, machetes or bush-saws, depending on their size. To feed each koala each day, browse from 1-1.5 trees is required. The time required between harvesting from the same tree is 10-12 months.
The establishment of plantations to provide food for koalas has become increasingly necessary in south-east Queensland. While this is partly because of the sheer number of koalas in captive environments, the rapid and widespread urban development of the region has placed additional pressure on the ability of remnant vegetation to support both wild and captive koala populations.
These best-practice principles will continue to be developed to inform the establishment and use of Eucalyptus plantations to sustain koala populations for years to come.
Summarised by Joanna Horsfall
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