Red Ironbark

24.05.17

Red ironbark is a distinctive medium-sized tree occurring naturally in parts of Victoria, New South Wales and southern Queensland. It is well suited to low rainfall areas and can be incorporated into farm windbreaks and shelterbelts and managed for high value sawlog or specialty timber production. It has strong and durable hardwood which is used in heavy engineering and construction but its deep red colour makes it an attractive option for high quality furniture.

Overview

Red ironbark is a general name that refers to four species of eucalypt. The two most common species are the mugga ironbark (Eucalyptus sideroxylon) and the narrow-leaved red ironbark (E. tricarpa). Two other species (E.fibrosa and E. crebra) also fall into the red ironbark category. Most red ironbark timber is currently sourced from native forests, however the number of markets for the timber provide some hope for a successful plantation industry.

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 water table 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 30-50 years.

Commercial trees are a long-term investment, with red ironbark taking 30 years to reach optimum specifications for harvest. While commercial trees are not as labour intensive as other agricultural enterprises, they do require maintenance to ensure a high quality product.

Facts and figures

  • The name red ironbark refers to four species of the Eucalyptus genus (E. sideroxylon, E. tricarpa, E. creba and E. fibrosa)
  • Red ironbark occurs naturally in parts of Victoria, New South Wales and southern Queensland
  • Red ironbark can be planted to complement an existing farm enterprise, or in plantations on separate land
  • It is a versatile timber and suitable for a range of markets
  • The timber is very hard, strong and durable and is used in construction and engineering
  • The deep red colour makes the timber an attractive choice for high quality furniture
  • Most red ironbark is sourced from native forests
  • It can take more than 30 years to reach harvest

Production status

In Australia, red ironbark logs are almost exclusively sourced from native forests.

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Map of current and potential growing regions

Uses

Red ironbark timber is very hard, strong and durable. Uses include:

  • heavy engineering construction, e.g. wharfs and bridges
  • railway sleepers
  • poles and posts
  • finer sawn timber products
  • firewood
  • furniture

Ironbark is becoming increasingly popular as a fine furniture and joinery timber due to its deep red colour and its durability and strength.

While growing, the trees provide shade and shelter for livestock and/or wildlife, habitat for nectar feeding birds and sugar gliders, and environmental services such as watertable management and erosion control.

The leaves of red ironbark contain cineole, an oil used as the base for many eucalyptus oil medicinal products including antiseptics, inhalants for cold and flu, and liniments to relieve muscle pain. Distillation of these could be another income derived from a plantation.

Production Requirements

Growing regions

The four species of red ironbark grow naturally throughout Victoria, New South Wales and into Queensland.

  • Mugga ironbark (E. sideroxylon) extends from Victoria through the western slopes of New South Wales into southern Queensland.
  • E. tricarpa is found in isolated areas from coastal regions of southern Victoria, central Victoria and into the south east of New South Wales.
  • Narrow-leaved red ironbark (E. creba) is found in the coastal, tablelands and western plains areas of central to northern New South Wales, and extends well up into Queensland in a belt between the coast and just west of the Great Dividing Range.
  • Broad-leaved red ironbark (E. fibrosa) is a less populous variety and can be found from the south coast of New South Wales to central coastal Queensland.

Soil type

Ironbarks grow best on deeper clay loams but can adapt to a wide range of soils including gravels, sands and ironstones and will tolerate saline and moderately waterlogged conditions.

Climate

Ironbarks are versatile trees with good drought tolerance and resistance to damage from frost and fire. Red ironbark is found naturally in woodlands or open forest, in areas with an annual rainfall of 450–1000mm. It can tolerate a minimum rainfall of 350mm, on poor shallow soils.

Varieties

There are significant differences in the performance of various provenances within the southern Red Ironbark species therefore, it is important that seed is collected from trees with the desired characteristics for the plantation. Seeds can be collected from forests (with a permit) but because there is significant variability within the species, a plantation based on collected seed could be established at high stocking densities to allow selection of desirable trees through the thinning process.

Improved seed is recommended for commercial plantings as it is selected from trees with superior form over a range of growing regions. Improved seed can be purchased from specialist nurseries.

Planting and crop management

Commercial trees can be integrated into existing agricultural systems to complement farm output or can be a separate use of available land, managed in plantations. While there is limited information available about growth rates of red ironbark in plantations, good site preparation and weed control, along with second year weed control and fertiliser application appear to promote faster growth.

When selecting the site, accessibility of the trees for maintenance and harvesting needs to be a consideration. Being on flat, accessible land, with good access roads and room to manoeuvre heavy equipment will make management easier and keep costs down over time.

Propagation can be from seed or seedlings directly sown into soil that has been prepared by spraying for weeds, ripping and mounding. Planted or emerging seedlings need to be protected from grazing animals by fencing or tree guards, and weeds need to be controlled before planting and during the first years of growth.

To encourage the straight stems and minimal branching of superior form commercial trees, the initial spacing of seedlings could be quite close (about 3 x 3m, or over 1,000 trees per hectare). Then, the poorly formed stems should be removed within the first few years resulting in around 400 good stems per hectare. Management at this stage includes pruning any forking or large branches from the main stem.

After three years, the best trees will have a stem diameter of approximately 12cm. At this stage, all malformed trees, or those with poor vigour, should be removed. Coppice regrowth would then need to be controlled and timely pruning of branches, as required, should continue to promote good form.

Trees can be harvested for sawlogs at around 1.5–2m in height, when the diameter of the trunk measures between 50–60cm, which can take more than 30 years to achieve.

Weeds, pests, and diseases

Weed control in plantations is particularly important before planting and during the first few years of growth, when competition by weeds for sunlight, nutrients and moisture can reduce growth rates.

When grown in plantations, red ironbark is susceptible to Armillaria root disease. While the actual causes of the disease are not clear, it appears anything that creates stress for the tree, e.g. severe drought or even prolonged waterlogging, may act as a catalyst. The fungus can survive in the soil for decades so apart from good hygiene to limit or stop the spread, eradication is not usually feasible.

Red ironbark is a host to mistletoe, which will draw water and nutrients from its host, and coppice regrowth is susceptible to attack by dodder-laurel. Red ironbark is also susceptible to minor attack by sawfly larvae.

Infrastructure Requirements

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.

If planting a commercial plantation of high value sawlogs, then tree farm-scale, tractor-based forestry equipment may be necessary, including logging winches and chains. Unless the plantation is large and consists of high value logs, it will not be economical to purchase specialised harvesting equipment or modify existing farm equipment to undertake harvest. Contractors with specialised equipment and machinery may be a more suitable consideration.

Harvesting & Processing

Initial site selection for commercial trees will have an influence on harvest method—well-spaced trees near access roads will enable easier and cheaper harvesting.

Harvesting is generally undertaken in two ways. If timber production is the sole objective of the plantings, then clear felling is the logical method. However, if the trees form part of a shelterbelt, then harvesting small volumes over a longer period of time is the more practical solution.

The timber is usually sold in two ways; either as ‘standing’ where a professional contractor pays a ‘stumpage rate’ to harvest and transport the logs, or ‘mill door price’ where logs are delivered to the timber mill having been harvested and transported privately or using contractors.

Unless the plantation is large and consists of high value logs, it will not be economical to purchase specialised harvesting equipment or modify existing farm equipment to undertake harvest. If the trees are large, pruned and well spaced, specialised equipment may not be required at all. A trained operator using a chainsaw, farm tractor, loader and log trailer may be able to undertake the job in a cost-competitive way.

Most processing of timber will occur at timber mills. Red ironbark is a very hard timber, which may preclude it from being processed on-farm without forestry equipment.

Markets & Marketing

Ironbark is considered a premium species. Traditionally a timber used in heavy engineering and construction, red ironbark is increasingly sought after for specialty, high value uses. The colour, strength and durability of the timber are highly marketable attributes and established markets exist for both wood and timber products.

Although total production volume of red ironbark is low relative to other native hardwoods, red ironbark timber may offer greater flexibility in choosing an end-product when the plantation is harvested, due to the number of market options, as well as an established place in the specialty timber market.

Before venturing into any commercial scale tree production, it is important to consider current and/or future markets before choosing a particular species to grow. 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), then there may be higher transport costs. 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.

Planting and managing for high quality sawlogs can counter some of the market uncertainty and absorb transport costs, as it is often easier to find markets for high value timber, even with longer transport distances involved. High value timber requires ongoing maintenance of trees, ensuring they are managed for the specifications particular to high value markets, essentially: good form, diameter and limited defects.

Consideration of local markets for the timber provides options should future markets change as described in the Risk/challenges section. Local markets could include the building or construction industry in the region, farm use as fence posts, or domestic use as firewood.

Risks & Regulations

Risks/challenges

Relative to other potential plantation species, ironbark is considered a low risk option for farm forestry investment due to its versatility and the number of markets for its timber. However, uncertainty and risk are inherent in all 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, 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.

To further manage risk, it is recommended that tree selection take into account the potential for local use for the timber. A timber versatile enough to be processed and used locally will limit some of the uncertainty around future markets if there are alternative opportunities to earn income. For example, local markets could include the local building and construction industry, farm uses such as fence posts, and domestic uses such as firewood.

An additional risk, specific to mugga and narrow-leaved red ironbark, is that they have a tendency to pipe, which means a hollow is formed in the centre of the trunk, reducing the yield and sizes of sawn timber.

Regulatory considerations

If seeking to establish a commercial plantation (the definition differs by state, but is generally defined at around 30-40 hectares) liaison with the relevant state government agency will be necessary. Regulatory systems vary across states, with some requiring plantations to be authorised and others requiring plantations to meet legislative requirements and/or a management Code of Practice.

Publications

Publications/information

Natural Durability of Five Eucalypt Species Suitable for Low Rainfall Area: Sugar gum, spotted gum, red ironbark, yellow gum and swamp yate RIRDC Research Paper (2008)

Farm Forestry Experiences RIRDC publication (2008)

Making Farm Forestry Pay RIRDC publication (2002)

Genetic Pollution from Farm Forestry RIRDC publication (2001)

Practical Farm Forestry RIRDC publication (1999)

Other resources

CSIRO’s Australian Tree Seed Centre A national collection and research centre with seed available for purchase

Farm Forest Line Free information service for on-farm forestry practice

Industry Bodies

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

Image Gallery

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Red ironbark tree has distinctive bark (source Museum Victoria)

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Red ironbark cut and polished into drink coasters

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Red Ironbarks in Dalyenong Reserve, VIC (source Ian Lunt)

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Red ironbark flowers