Two types of banksia woodland exist in Tasmania, those composed of saw-toothed banksia (Banksia serrata
) and those consisting of honeysuckle (Banksia marginata
Saw-toothed banksia populations (Banksia serrata
) are of considerable importance. In Tasmania the species is only known to occur naturally in the north-west at Sisters Beach, the Dip Road and in Rocky Cape National Park. Very small populations also occur on Flinders Island in Bass Strait. Saw-toothed banksia usually grow on soils that are derived from very old and hard rocks such as quartzite (white coloured rock). As the saw-toothed banksia is so rare in Tasmania and the natural populations here represent the most southern geographic distribution of them in the world it is very important that we protect them for the future.
The second species, Honeysuckle (Banksia marginata
) varies in appearance, forming a shrub or small tree. It is widespread in Tasmania and forms scrub and woodland on coastal sand dunes where the fire frequency is low. Honeysuckle also form groves in the Midlands, usually on sandy soils. Some of these groves are extensive, up to 2 km in length with magnificent old trees, although the majority are small copses. Inland stands of banksia were probably once extensive in the grassy lowlands throughout south east Australia. Today, few remain and those that do are mostly in poor condition with weedy understories and little regeneration. Coastal stands of banksia generally survive in better condition.
Where to see saw-toothed banksia woodland
Saw-toothed banksia is seen growing next to the road leading into Rocky Cape National Park and in the dry sclerophyll forest and coastal scrub near Sisters Beach.
Where to see honeysuckle woodland
A small grove of Banksia marginata
woodland can be seen on the eastern side of the Midlands Highway a few kilometres south of the rest area between Oatlands and Tunbridge. A coastal stand exists on the northern end of Kingston Beach near Hobart.
Biodiversity values of banksia woodland
Coastal Banksia marginata
woodlands are well reserved and in good condition. However, there are few good stands of the inland banksia woodland which makes this vegetation type valuable for conservation. Large groves of Banksia serrata
are reserved within some areas of the Rocky Cape National Park, particularly to the south and east of Sisters Beach; However, all saw-toothed banksia habitats are of very high conservation significance within Tasmania.
General management issues of banksia woodland
Fire and grazing are the major management tools in banksia scrub and woodland.
Banksias have a hard seed that is stored in a cone and released after fire. However, fire is not essential for regeneration and in some areas banksias regenerate in the absence of fire. Drought and high temperatures also lead to seed release.
- Burns in saw-toothed banksia and honeysuckle woodland should always be of low intensity as hot fires may kill many of the younger trees. Again burns are best conducted in Autumn and must only be done with the permission of the relevant authorities and under suitable conditions.
- It is generally recommended that woodland and scrub that contains saw-toothed banksia be burnt at a frequency of 10 to 15 years. This frequency will enable the banksia seedlings that regenerate after the fire to mature and set seed in preparation for the next fire. More frequent fires may reduce to abundance of saw-toothed banksia at the site.
- Fencing a banksia grove allows for better stock control.
- If regeneration has occurred exclude stock until the young trees are out of their reach. Electric fencing is effective for a small area.
- Leave dead branches on the ground as they act as a cage protecting the young banksias and other species from browsing animals.
- If there is a dense grassy sward and no regeneration, crash grazing a large mob of sheep for a short time may help regeneration by reducing the competition from rank grassy swards.
The root-rot fungus (Phytophthora cinnamomi
) in Tasmania is responsible for the death of many banksia trees.
- Prevent the introduction of soil and plant material from other areas that you suspect may be affected by the root-rot fungus.
- Remove the soil from and wash down vehicles, machinery and walking boots thoroughly before entering areas that contain saw-toothed banksia.
Rank grasses such as Yorkshire fog, cocksfoot and brown-top bent often form a dense sward in banksia groves. Crash grazing for a short period of time may help to reduce these grasses but seedlings may also be lost. Weeds in Your Bush provides more information on weeds and their management.
Weed invasion rarely affects stands of saw-toothed banksia, however, in wetter gullies and on slightly deeper soils blackberry, cotoneaster, blue-bell creeper, holly, mirror bush, monterey pine and gorse can severely affect saw-toothed banksia seedling establishment and growth.
Banksia woodlands are often difficult areas in which to establish trees, including banksias, because of the competition from grasses and the poor sandy soils. These soils often have large numbers of ants that feed on the seed. Experiments with hand-sowing seed, including banksia seed, have not led to the establishment of young plants.