Tasmanian blue gum

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.

Tasmanian blue gum (Eucalyptus globulus subsp. globulus) is a commercially important plantation tree species widely grown across southern Australia and in Mediterranean climates around the world. It is typically grown as a short rotation (10-15 year) crop producing high-quality woodchips that are predominantly exported for pulp and paper manufacturing in Asia. It is Australia’s second most important plantation species, with 344,500 ha (20% of all plantation and 47% of hardwood plantations). Its commercial distribution in Australia is concentrated in Victoria and south-west WA, with important areas in Tasmania and South Australia.

Overview

Tasmanian blue gum (Eucalyptus globulus subsp. globulus) is a commercially important plantation tree species widely grown across southern Australia and in Mediterranean climates around the world. It is typically grown as a short rotation (10-15 year) crop producing high-quality woodchips that are predominantly exported for pulp and paper manufacturing in Asia. It is Australia’s second most important plantation species, with 344,500 ha (20% of all plantation and 47% of hardwood plantations). Its commercial distribution in Australia is concentrated in Victoria and south-west WA, with important areas in Tasmania and South Australia.

Species characteristics

Endemic to Tasmania and Victoria, Tasmanian blue gum in its natural form is a straight, gum barked tree grows in woodland, open forest and tall open forest vegetation types. In optimal plantation conditions it is a fast growing species. Mean annual increments can exceed 20 m3/ha/yr with young trees gaining up to 2 m height per year.¹

As a long-lived tree, under natural conditions maximum heights up to 70 m can be reached, depending on site quality. It is able to regrow as coppice following harvest or severe disturbance.

Table 1: Environmental requirements for Tasmanian blue gum.

Current estate extent and location

In its natural habitat Tasmanian blue gum grows in low elevation parts of eastern Tasmania, the Bass Strait Islands, and South Gippsland and the Otways in Victoria.

From the early 1990s to late 2000s, there was a rapid expansion in the area of Tasmanian blue gum plantations, driven by Managed Investment Schemes (MIS). When the MIS industry collapsed, most of these plantations were

acquired by institutional investors, which subsequently rationalised the blue gum plantation estate to more economically viable sites. Tasmanian blue gum plantations are concentrated in southwest Western Australia and the Green Triangle on the Victorian / South Australian border, with important areas in Tasmania (see Figure 1). Tasmanian blue gum is grown as a plantation species extensively around the world. Chile, Ecuador, Uruguay, Ethiopia, China, Portugal and Spain have large estates, with significant areas also grown in other countries with Mediterranean climates.

Figure 1: Distribution of Tasmanian blue gum plantations in Australia (ABARES, ²⁰²¹)

Products, properties and markets

Tasmanian blue gum grown in plantation settings has very different wood properties to the same species in natural forest environments. Plantation blue gum is valued for its short, high-quality fibres, high pulp yield and high basic wood density. These characteristics make it the most sought after timber species for manufacturing premium paper for printing.³

The trees are grown on short rotations and harvested before the development of heartwood. Tasmanian blue gum grown in natural forests is a pale straw to brown timber that is hard, dense, strong, moderately durable and often has interlocked grain. Harvesting in natural forests occurs much later in its lifecycle. It is used for flooring, joinery, furniture, light and heavy construction, poles, piles, sleepers and firewood.⁴ Sawn timber and peeled or sliced

veneer can be produced from smaller diameter plantation grown logs with advanced sawing and drying strategies.⁵ Hardwood sawmills in Victoria and Tasmania utilise Tasmanian blue gum saw logs sourced from native forests.

While most are not configured to efficiently and effectively process plantation blue gum logs, there are some sawmills

and veneer processors in both Victoria and Tasmania that are processing plantation logs.

In Australia, Tasmanian blue gum plantations are grown predominantly to produce wood chips for export to Asia to be used in pulp and paper products. Major woodchip export facilities are in south-west Western Australia, Victoria and Tasmania. Domestic residue markets may take materials that don’t meet market specifications due to charcoal content and there are small-scale, local markets for minor products and firewood. Non-wood products include eucalyptus oil and honey.²

Ecosystem services and community benefits

Blue gum plantations provide several ecosystem benefits, including shade and shelter, lowering of water tables in

salt-affected areas, generation of carbon credits, and wildlife habitat, particularly for koalas and native birds.

Many farmers in southern Australia have integrated Tasmanian blue gum plantations into their agricultural enterprises as woodlots, wide shelterbelts or plantations with wide spaced rows. Strategically placed plantings benefit pasture and crop growth and improve growing conditions for livestock through provision of shade, shelter or refuge. The fast growth and relatively high rates of water use of the species is also useful in lowering watertables in salinity-prone farmlands.

There are several opportunities for Tasmanian blue gum plantations to generate Australian Carbon Credit Units under the Carbon Farming Initiative – Plantation Forestry method. These include:

1. The establishment of new plantations on non-forested or wetland ^area.
2. 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 a plantation.
3. Transition of the plantation to permanent ^forest.

Eucalypt plantations support wildlife populations by extending habitat around native vegetation remnants and providing landscape connectivity.^{6, 10} Tasmanian blue gum is one of several preferred species for koalas and plantations are recognised as providing good additional habitat, particularly in south-west Victoria where there are robust populations in native forests and woodlands.⁷

Risks and their management

Blue gum plantations are subject to a range of risks that are common to Australian forestry including fire and climatic extremes, neighbourhood issues relating to chemical spraying, streamflow, noise, dust and amenity issues and unsuitable local road infrastructure. Species specific forest health, invasiveness and koala risks are also worth noting.

The species has a medium to high susceptibility to insect attack. Eucalyptus weevil, autumn gum moth, Christmas beetle, leaf blister sawfly, chrysomelid beetles, African black beetle, spring beetles and wingless grasshopper are all known to cause economic damage in blue gum plantations.⁸ Active treatment and monitoring, particularly soon after establishment, are essential to successful establishment of plantations.

Tasmanian blue gum has potential to become highly invasive when grown in similar conditions to its natural environment.⁹ Wilding establishment in Australia has been kept to low levels as plantations are in most cases harvested within 15 years, before full reproductive capacity is reached. Wildings need to be monitored and removed along plantation boundaries, particularly for older plantations adjoining native forest.

Harvesting operations in Victoria have potential to cause koala injury and death if not carefully managed. Specific ^wildlife

regulations apply, and forest managers may need to implement search and spotting protocols during operations.

Management practices

Economy of scale is an important consideration for plantation growers considering Tasmanian blue gum because

it has a narrow range of markets and financial viability is sensitive to growth rates and haulage distance. The minimum viable area for harvest is generally about 10-15 ha for a productive site, close to market with no significant challenges associated with access and harvest. Larger areas are required for economy of scale for more challenging sites that are further from market.

The species is typically grown industrially as plantations. Other configurations suitable for farm forestry include ^multiple

smaller woodlots, wide shelterbelts, plantations with wide spaced rows.

A typical silvicultural regime for a first rotation blue gum plantation involves the following ^steps.

• site preparation, usually involving cultivation to provide suitable soil and microclimate for seedlings.
• pre-plant weed control.
• planting of seedlings at a density of at least 1,000 stems per ^hectare.
• establishment fertiliser (may not be required depending on fertiliser history).
• Insect control (can involve physical barriers or soil injected ^{insecticide).}
• Regular monitoring for insects, disease and weed competition which may trigger further ^treatment.
• Mid-rotation inventory to monitor growth and ^{productivity.}
• Pre-harvest inventory to determine the potential harvest ^volume.
• Clear fall harvesting and onsite processing of log or chip, generally from 8-15 ^years.

Second and potentially third rotations can be regenerated as coppice from harvested stumps, reducing new establishment costs, although this comes at the expense of productivity. Coppiced sites typically produce lower volumes than replanted sites as some stumps die at each operation and the trees grow slower. Alternatively, sites can be replanted after harvest. Replanting provides the opportunity to introduce new genetics and fully restock the site. Because coppicing is much lower cost, it may be more financially attractive than replanting. If a site is replanted, the previous rotation stumps must be killed, and the site will require slash treatment such as chopper rolling, heaping or possibly burning. New seedlings are planted and intensive weed and insect control regimes are implemented. Coppice sites can be re-stablished with little more than monitoring for weeds and insects and applying appropriate controls. Nitrogen and phosphorus fertiliser is more likely to be needed in later rotations.

Financial returns

The financial profile for a blue gum enterprise is typically characterised by up-front establishment and maintenance costs and a single revenue event when the plantation is harvested, making it relatively straight forward when compared to some other types of forestry. The following table presents a sample cash flow profile for a Tasmanian blue gum plantation in-field chipping operation in south west Victoria, assuming 300 green metric tonnes per hectare at harvest (mean annual increment of 20 m³/ha/yr). Haulage distance is 60 km and price is $70/green metric tonne.

Bibliography and further reading

1 Booth, T.H., Jovanovic, T. Snowdon, P., Mummery, D., Battaglia, M., Sands, Pl and Fife, D.N. (2007) Modelling the potential productivity of commercial farm forestry species, May 2007, RIRDC Publication no 05/175, RIRDC Project No CSF-56A.

2 Clark, B., McLeod, I and Vercoe, T. (2008) Trees for farm forestry: 22 promising species, March 2009. RIRDC

Publication No 09/015, RIRDC Project No CSF-56A.

3 Isabel Carrillo, Claudia Vidal, Juan P Elissetche & Regis T Mendonça (2018) Wood anatomical and chemical properties related to the pulpability of Eucalyptus globulus: a review, Southern Forests: a Journal of Forest Science, 80:1, 1-8,

DOI: 10.2989/20702620.2016.1274859.

4 WoodSolutions website, https://www.woodsolutions.com.au/wood-species.

5 Washusen, R. (2013) Processing methods for production of solid wood products from plantation grown Eucalyptus species of importance to Australia, April 2013, Forest & Wood Products Australia

6 Lindenmayer, D.B and Hobbs R.J. (2007) Fauna conservation in Australian plantations forests – a review,

RIRDC Publication No 05/128, RIRDC Project No UMU-31A

7 Heard, G.W. and Ramsey, D.S.L. (2020). Modelling Koala abundance across Victoria. Unpublished Client Report for Biodiversity Division, Department of Environment, Land, Water and Planning. Arthur Rylah Institute for Environmental Research, Department of Environment, Land, Water and Planning, Heidelberg, Victoria.

8 Loch, A.D. and Floyd, R.B (2001) Insect pests of Tasmanian Blue Gum, Eucalyptus globulus globulus in south-western Australia: History, current perspectives and future prospects, Austral Ecology Volume 26, Issue 5 October 2001.

9 Larcombe, M.J., Silva, J.S., Vaillancourt, R.E., and Potts, B.M. (2013) Assessing the invasive potential of Eucalyptus

globulus in Australia: Quantification of wilding establishment from plantations. Biological Invasions 15 (12).

10 Olsen, P.F. (2022) Bird Monitoring in Plantations – BirdLife Australia and PF Olsen Australia bird monitoring program presentation. https://pfolsen.blob.core.windows.net/productionmedia/5596/bird-monitoring-in-plantations_april2022.pdf.

ABARES 2022, Australian plantation statistics 2022 update, ABARES, Canberra, August, CC BY 4.0. DOI: https://doi.org/10.25814/8ghb-em15.

CABI Digital Library, Eucalyptus globulus Datasheet 29 June 2015.

Cao, R, Gong, X., Feng, J. and Yang, R. (2022) Niche and range dynamics of Tasmanian Blue Gum (Eucalyptus globulus Labill.) a globally cultivated invasive tree, Ecology and Evolution Volume 12, Issue 9.

DPI, Map User Notes: Eucalyptus globulus, E. nitens and Pinus radiata Suitability Map, Tasmanian Government The Wood Database https://www.wood-database.com/blue-gum/

Timber Research Unit (2006), Tasmanian Blue Gum,

https://www.utas.edu.au/ data/assets/pdf_file/0018/511524/Bluegum.pdf.