Dicksonia antarctica growing in Tasmanian Wet Eucalypt forest

Of the five tree ferns species that grow in the Native forests of south eastern Australia only two continue to be harvested for any commercial purposes, these being Dicksonia antarctica the Soft Tree fern or Manfern and Todea barbara, the Austral King fern. Of these two only the Soft Tree fern or Manfern is used to any great extent, being a popular ornamental species within the nursery trade. In addition to being widespread throughout the cool and wet forests of south eastern Australia, occurring from sea level to altitudes greater than 1000 metres, it possesses a very distinctive arborescent growth habit that, with its thick fibrous trunk and crown of spreading dark green foliage, give it a very attractive appearance.

Dicksonia antarctica's popularity as a garden ornamental in south eastern Australia is also related to it being very easy to grow in shady moist areas where many trees and shrubs will not survive and its hardiness. It thrives in cool moist conditions, can withstand frost, snow and very low temperatures, and is able to tolerate a fair degree of exposure to the sun.

Distribution of Dicksonia antarctica
in Victoria (source Duncan and Isaac 1986)

Moreover it doesn't require much maintenance other than regular watering, is very resistant to physical damage and rough handling, can be stored indefinitely when provided with adequate water and shade, and can withstand long periods in containers. It can also help with weed control in the garden as its dense crown can shade out many problem species of suburban gardens and has been suggested to have allelopathic abilities (Neyland 1986). The fibrous, water absorbing and retaining nature of the trunk also make it ideal for use as a planter when it is cut into slabs or pots.

Its not surprising then that a flourishing trade between Tasmania and the nursery markets of mainland Australia in live Manfern stems exists. Considerable interest has also been shown by local nurseries in Tasmania in developing an international export market. However, unauthorised harvesting of trunks on both crown land and within private forests in Tasmania in the 1980s was a major cause of concern (Forestry Commission Tasmania 1989). Dicksonia antarctica's  slow growth rate of 30cm over 10 years and long age to reproductive maturity, approximately 23 years, make it sensitive to over harvesting (Forestry Commission, Tasmania 1988), whilst its important ecological role as a substrate for the growth of many epiphytic ferns make it an important key species in maintaining the floristic diversity of native forests. It is also sensitive to the combined effects of mechanical disturbance and regeneration burning typical of many forest harvesting operations in its natural range (Hickey and Savva 1992; Ough and Murphy 1996).

As a result a management plan was put into place by the then Tasmania Forestry Commission and a licensing system implemented in other states. A quota of 500 000 live stems to be harvested per year was set and other management prescriptions put into place in Tasmania, such as no harvesting from areas containing no fewer than 100 stems per hectare, no harvesting from stream side reserves and all harvesting operations being on the basis of a thinning operation in which the whole stem is taken (Neyland, 1988). In addition no live Manferns are to be harvested unless another of the same size class is left within 20 metres, except in areas to be deforested (Neyland 1988). However, despite this the Tasmanian management plan was not accepted by the Australian National Parks and Wildlife Service and the then Tasmanian Forestry Commission did not see the industry as being commercially important enough for them to warrant any further effort (Forestry Commission, Tasmania 1990). As a consequence a tree fern export industry has yet to be established. In Victoria and New South Wales, licenses have to be obtained and stems are only to be taken from areas to be deforested or from areas to be harvested for wood products.

Because of the potential localised conservation effects of tree fern gathering, the administrative costs to organisations to oversee that harvesting is at least potentially sustainable and the unpopularity of using native forests for commercial production, other means of supplying the demand for tree ferns have been suggested, such as nursery propagation. Interestingly, Manferns can grow quite well under pine plantations where there is sufficient moisture and appropriate soils (Neyland 1988). Although relatively easy to propagate from spores Dicksonia antarctica's  slow growth rates, taking up to 75 years to reach 6 feet, suggest that the large sizes that people seem want in their gardens will still have to come from native forests for many years to come whilst Manfern planters and pots can be sourced quite readily from nurseries or even combined Manfern and pine plantations.

References:

Duncan, B. D. and Isaac, G.(1986), Ferns and Allied Plants of Victoria, Tasmania and South Australia. Melbourne University Press.

Forestry Commission Tasmania (1989), Annual Report 1988-1989. Forestry Commission of Tasmania

Forestry Commission, Tasmania (1990) Annual Report 1989-1990. Forestry Commission of Tasmania

Neyland, M. (1986), Conservation and Management of Tree Ferns in Tasmania. Wildlife Division Technical Report 86/1 National Parks and Wildlife Service Tasmania

Neyland, M. (1988), Draft Management Plan for Tree Ferns in Tasmania's Crown Forests, Forestry Commission, Tasmania

Links

http://www.anu.edu.au/Forestry - Forestry

http://www.sim.com.au/ferns/ - Australian Tree Ferns

http://student.uq.edu.au/~s371495/ferns.html - The Wonderful World of Ferns

http://www.home.aone.net.au/byzantium/ferns/ - Ferns of the Canberra Region

http://www.home.aone.net.au/byzantium/ferns/growing.html - Raising Ferns from Spores

http://www.anbg.gov.au/ferns/ferns.html - Native Ferns for Cool Climates

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