This document is part of a series of four guidance reports that cover topics related to small-scale farm forestry, private native forestry, and Indigenous managed forest lands. Learn more about the other reports and documents via this link.
Spotted gum (Corymbia maculata) is one of Australia’s most important native forest timber species and has also been adapted as a plantation species. In the plantation setting, it is a durable, drought-resistant tree, which historically was grown widely on farms in semi-arid areas across southern Australia and in similar climates around the world. It is mostly grown in shelterbelts and woodlots established for stock shelter, farm timbers and firewood. More recently it has been grown as a plantation species for high-end sawn timber markets.
Overview
Spotted gum (Corymbia maculata) is one of Australia’s most important native forest timber species and has also been adapted as a plantation species. In the plantation setting, it is a durable, drought-resistant tree, which historically was grown widely on farms in semi-arid areas across southern Australia and in similar climates around the world. It is mostly grown in shelterbelts and woodlots established for stock shelter, farm timbers and firewood. More recently it has been grown as a plantation species for high-end sawn timber markets.
Species characteristics
Spotted gum has good, erect form, moderate drought tolerance, and can grow on a wide range of soils. Its deep lateral roots provide access to water held deep in the soil profile, but it cannot tolerate waterlogging. The selection of appropriate variants and provenances within these areas is crucial for plantation success.1 In the plantation setting it is a moderately fast-growing species and its growth rate can be influenced by silvicultural intervention and environmental factors. Mean annual increments (MAI) vary from 0.1-2 m3/ha/yr in native forests 2 and 10-16 m3/ha/yr in commercial plantations 3.
| Environmental factor | Variables |
| Mean minimum temperature | 0-7°C 1 |
| Mean maximum temperature | 25-30 °C 1 |
| Mean annual temperature | 10-19 °C 1 |
| Annual rainfall | 750-1,750 mm 1 |
| Frost | Only a mild tolerance to frost, should avoid <-2°C 1 |
| Maximum dry season duration | 0-5 months 1 |
| Soil texture | Spotted gum plantations thrive in varied soil types, moderately heavy soils being optimal for growth. 3 |
| Depth | Suited to deep, moist, well-drained soils. |
| Drainage | Intolerant of waterlogging. 1 |
| Soil chemistry | Prefers pH 4-pH 10 soils 4 |
| Salinity EC | Low to slight salt tolerance, avoid anything higher than 4 ds/m 4 |
Current estate extent and location
Spotted gum is naturally found in coastal areas of south-east Australia and grows in taller forests on slopes up to 950 m elevation, with a small, isolated stand in Victoria.5 Extensive provenance selection for plantation spotted gum timber production began in the 1990s and 2000s but considerable variation has been observed in material sourced from natural stands. In irrigated trials, provenances from Warwick in Queensland and Wingello State Forest in New South Wales have performed well, with the Warwick provenance appearing to be one of the more frost tolerant.5
The documented extent of spotted gum plantations in New South Wales and Queensland is about 1,000 ha.9 However, this is likely to be a significant underestimate and it is probable that a large proportion of the 28,000 ha categorised as ‘other hardwood species’ in those two states is actually spotted gum.
In recent years, spotted gum plantations have expanded in inland regions of Australia, showing potential in farm forestry, mine rehabilitation, and irrigation areas. Small-scale plantings have also been successful in other countries like South Africa and Israel. Future commercial plantations are expected in central and southern Queensland, with moderate rainfall.1 They are also grown in commercial plantations in South Africa, Brazil, China, North America and Israel, with certain plantations utilising irrigation methods.4, 6
Products, properties and markets
Spotted gum is an important commercial native forest tree species in Queensland and New South Wales that is valued for its superior quality, dense, durable and visually appealing timber. Since 1992, there has been an increasing interest in planting this species for timber production. Its popularity stems from its rapid early growth, favourable shape, and the quality of its versatile timber. Well-managed regrowth forests can also provide commercially viable timber supplies.
Spotted gum timber has excellent properties, with high recovery rates for top-quality appearance-grade wood, making it suitable for a wide range of uses. It has a well-established market and is in demand both nationally and internationally. Timber from both natural and planted stands of spotted gum is commonly used for various purposes requiring strength, durability and resilience. It is common in applications such as heavy construction, tool handles for high impact forces, house fabrication, flooring, mine timbers, plywood manufacture, boat building, charcoal and firewood.3, 1
Spotted gum is also highly favoured by honey producers because of the taste of the honey produced and its prolific flowering and pollen production.1
Ecosystem services and community benefits
Apart from its commercial significance, spotted gum can also deliver a range of ecological benefits, including providing shade and shelter from winds, supporting diverse habitats, contributing to biodiversity, managing soil salinity and enhancing water quality.4
Spotted gum is suitable for multi-row windbreaks, particularly when planted alongside shorter ‘draught stopper’ species. It is also highly attractive for ornamental purposes, with mature trees providing ample shade. The flowers of spotted gum are not only a valuable nectar source for birds, insects, gliders and flying foxes, but also attract insect-eating birds.
Additionally, the seeds of spotted gum serve as a food source for native birds and insects. Notably, spotted gum trees are favoured as habitat trees for koalas.4
There are several opportunities for sugar gum plantations to generate Australian Carbon Credit Units under the Carbon Farming Initiative – Plantation Forestry. These include:
- The establishment of new plantations on non-forested or wetland areas.
- The decision to continue a plantation rather than convert it to other land use because the opportunity to participate in the Emissions Reduction Fund (ERF) makes it viable to continue managing the land as plantation.
Transition of the plantation to permanent forest.
- Conversion of a short firewood-only rotation to a longer term saw log rotation.
Risks and their management
Frost is a major issue for spotted gum, especially for establishment in inland areas of southern Australia with winter dominant rainfall. The first two to three years is the main danger period. To minimise frost damage, spotted gum plantings should be restricted to upper slope or ridge sites with ample air drainage. Variation in frost tolerance within and between species has been identified.
Suitable planting areas for spotted gum include 600–900 mm annual rainfall areas in inland southern Australia and 600–1,200 mm rainfall in eastern New South Wales and Queensland. However, the selection of appropriate provenances within these areas is crucial for plantation success. Depending on provenance spotted gum is moderately drought tolerant and slightly salt tolerant.7
Heavy branching, forking and a high incidence of kino rings can lower the quality of the timber produced by the trees.1
Management practices
Spotted gum has the potential for successful establishment by following similar preparations and treatments as other eucalypt species.4
| Cultivation | Minimal site cultivation is required. However, it is crucial to avoid planting sites that have frost pockets or hollows. Surface cultivation to loosen compacted topsoil may be beneficial.1 |
| Weed control | Typically, a combination of residual and knock-down herbicides, commonly glyphosate, is used to control weeds before planting.1 |
| Growing stock & Planting | To enable the utilisation of machinery, it is necessary to have a gap of 3–5 m between rows. The specific spacings and planting arrangements can differ, but recommended initial spacings for woodlots are 3 m by 3 m (equivalent to 1,111 trees/ha) and 4 m by 2.5 m (equivalent to 1,000 trees/ha). These spacings facilitate quick coverage by the tree canopy, minimise issues with weeds, encourage desirable tree shape, and enable the selection of samples to achieve
a final stocking density of 200–300 trees/ha.4 |
| Fertiliser | The application of fertilisers has an impact on the growth of spotted gum trees. Typically, nitrogen fertilisation leads to growth improvements, and in some cases, phosphorus application can also yield positive results. Moreover, the presence of the micronutrient boron has been discovered to promote growth in various regions of North East Victoria. Additionally, zinc and copper responses have been noticed in coastal areas.5 |
| Post plant weed control | It is beneficial to ensure weeds are controlled for the first 2-3 years.1 |
| Monitoring | Regular monitoring for frost, disease and weed competition that may trigger further treatment. |
A model for plantation management is a rotation length of between 30-40 years with 1-2 thinnings.
| Option | 1st thinning | 2nd thinning | Sawlog harvest |
| Early 1st thinning (Huynh et al. 2023) | Pre-commercial at 3 -6 years | 7-9 years | Early 1st thinning 8 |
Financial returns
Spotted gum is a highly desired species. However, there is little information available about prices for spotted gum products grown in plantations. As the existing plantation resource matures and spotted gum resource becomes more challenging to access from native forests, it is expected that markets for high quality durable products, such as poles as well as flooring, will respond.
Bibliography and further reading
1 Clarke, B., I. Mcleod & T. Vercoe (2009) Trees for farm forestry: 22 promising species. Rural Industries Research and Development Corporation.
2 Ngugi, M. R., D. Doley & M. Cant (2015) Growth rates of Eucalyptus and other Australian native tree species derived from seven decades of growth monitoring. Journal of Forestry Research, 4(26).
3 Queensland Department of Agriculture, Fisheries and Forestry (2013) Spotted gum timber harvest report, Brisbane.
4 Schultz, E. & D. Pendergast (2017) Timber Management for spotted gum. Forest Industry Australia.
5 Vernon, G. R. (2012) Spotted gum growth model, Canberra.
6 McDougal, A. S., L. G. Bates, A. S. Brack & A. A. Furr (2022) Australian native forestry. Australian Forests Society.
7 Johnson, D., D. McLeod, B. Mullen & D. Neumann (2011) Forests for future carbon management. Journal of Forest Products.
8 Huynh, N. Q., W. H. Francis & L. J. Weiner (2023) Spotted gum plantation management. Australian Forestry Journal.
9 Forestry Australia (2021) Australian forest plantation statistics report, Canberra.
Boland, D.J., M. Brooker, G.M. Chippendale & N. Hall (1994) Forest Trees of Australia. Fourth edition, CSIRO.
Clark, N.B & C.C. Hicks (2003) Evaluation of the pulpwood quality of 13 lesser-known eucalypt species. Appita Journal, Volume 56, pp. 53-60.
Grant, D.J. & W. Joe (1994) Strength grouping of three New South Wales eucalypt species – a reassessment. Australian Forestry, 57(1), pp. 31-36.
Mathers, N., R.C. Dalal, T.N. Maraseni & D.E. Allen (2010) Afforestation of agricultural land with spotted gum (Corymbia citriodora) increases soil carbon and nitrogen in a Ferrosol. Brisbane, 19th World Congress of Soil Science.
