Silky oak has been grown widely throughout Australia as an ornamental tree for almost 100 years.

Observations of ornamental plantings indicate that silky oak is drought tolerant, grows on a wide range of soil types, has a tough bark (making it suitable as a shade tree in paddocks of grazing animals), produces flowers and gum that support native wildlife and can grow large enough for milling within a reasonable time. However, in some states, it is considered a minor environmental weed.

Due to its limited availability from native forests silky oak has been of minor timber commercial value but it has recently gained recognition as a potential planting species.

Silky oak has had a good reputation for quality furniture in the past, and continues to be sought for specialised woodworking, cabinetry and furniture, suggesting a market might exist for the timber in the future.

Commercial farm trees have the potential to offer a range of benefits to farmers and land managers by increasing Australia’s long-term timber supply while contributing social, economic and environmental benefits to regional areas.

Trees are often planted to provide windbreaks and shelterbelts for crops and livestock, to manage the watertable or to protect topsoil from erosion. However many landholders, using existing infrastructure and integrating tree management practices into existing farm operations, may be able to earn an alternative income from planting farm trees that earn a commercial return. The risk inherent in all commercial tree operations is the long period between establishment and harvest which can range from 30 to 50 years with no financial returns in the interim.

The timber of silky oak is pinkish brown with a typical oak grain and is used in:

• cabinet work
• furniture
• wood turning
• plywood
• panelling
• veneers.

Growing regions

Silky oak occurs naturally on the coastal ranges in northern New South Wales and south east Queensland in subtropical to dry rainforest and wet sclerophyll forest.

Soil type

Silky oak prefers fertile basalt and alluvial soils but also grows on moderately shallow sedimentary soils.

Climate

Silky oak grows naturally in warm humid conditions of the subtropics but it will tolerate dry conditions and moderate frosts.

Varieties

Although there has been some limited provenance testing of silky oak (Grevillea robusta) there has been no varietal selection of the species for plantation purposes.

Other ‘oak’ trees, native to Australia have been milled for their timber. A closely related species to silky oak is the silver oak or beefwood (Grevillea parallela). It is a desert species and doesn’t grow as large but has a darker timber that is prized by wood turners. The northern silky oak (Cardwellia sublimis) found in far north Queensland is from the same family (Proteaceae) as the Grevillea, and was once widely milled from native forests.

Land is the main infrastructure requirement for commercial tree growing.

If planting trees on a small scale and integrating them into the agricultural enterprise as windbreaks and shelterbelts, then manual maintenance, including pruning and thinning, can usually be managed with a chainsaw and farm equipment.

Silky oak can be milled by a skilled operator with very simple equipment, for example a chainsaw and mobile milling unit, and is easily air-dried.

Note that the wood contains a chemical that can cause an allergic reaction in some people, so care must be taken when handling the timber.

Silky oak is considered a minor commercial species, therefore, consideration of silky oak as a business enterprise is highly speculative.

For all timbers, but especially species like silky oak, it is important to consider current and/or future markets before establishing a small or large plantation. However, with commercial trees taking around 30 years to provide a return on investment (in most cases) it is difficult to accurately predict future market opportunities at establishment.

Distance from markets will affect the profitability of a commercial timber enterprise, generally speaking, when the plantation is more than 100km from the processing centre (or road conditions are difficult), as transport costs can be high. The closer the planting is to the processing centre, the greater the return for any given product, particularly if providing a high volume of a lower value timber, such as pulpwood and woodchips.

Risks/challenges

Uncertainty and risk are inherent in commercial tree operations due to the long period of time between establishment and harvest (around 30 years).

Some of the risks include:

• mills closing or relocating, leaving plantings at an uneconomical distance from processors
• timber preferences or ‘fashions’ changing, resulting in decreased markets as certain colours or grades of timber fall out of favour with designers and builders and consumers
• government policy changing, impacting on industry structure and profitability
• alternative products developing, resulting in a falling demand for timber.

Alternative benefits from commercial tree plantings should be investigated to help reduce exposure to these risks. It is recommended that a short-, medium- and long-term return or benefit be identified when considering planting commercial trees. For example, a short-term benefit could relate to carbon sequestration or watertable abatement. A medium-term benefit may be derived from the trees providing a windbreak or shelterbelt for crops and livestock, and a long-term benefit might be income from harvested timber.

Publications/information

Silky Oak – Australian Agroforestry

Australian Forest Growers – the national association representing private forestry and commercial tree growing interests in Australia