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Forestry Fact Sheet Number 13

 

Introduction

In the South East, firewood is usually sourced from dead or fallen trees on farms, but this supply is diminishing and the community is becoming increasingly aware of the habitat value of these trees. To supplement the supply, landowners are now considering woodlot grown firewood or using the thinnings from sawlog plantations.

 

This fact sheet provides information to assist in the management of woodlots for firewood production. The topics include:

• species
• stocking
• management
• harvesting and market specifications  

For further information on growing trees, see the web page Farm Forestry and the following PIRSA Forestry Fact Sheets:

Growing trees in the Upper South East

Growing trees in the Lower South East

Growing trees on Kangaroo Island

 

Species Selection

It is important to select an appropriate species for the proposed site to ensure the best survival and growth rate of the trees.  Species selection should also reflect the objectives of the grower. See Table 1 for details of potential firewood species for the South East of South Australia.

 

Table 1 Potential firewood species for the South East of South Australia and their firewood properties, other uses, site requirements and species attributes

 

Other uses

Species	Firewood	properties
	Splitting	Ignition	Coaling	Sparks (Splitting)
Eucalyptus occidentalis Swamp yate	Difficult	Poor	Excellent	Few	Fencing posts/poles, preservative treated timber, and heavy construction
Eucalyptus cladocalyx Sugar gum	Difficult	Poor	Excellent	Few	Panelling, heavy construction, building framing, decking, and internal flooring
Eucalyptus globulus Tasmanian blue gum	Fair	Fair	Good	Few	Fencing posts/poles, preservative treated timber, building framing, internal flooring, and woodchips
Eucalyptus camaldulensis River red gum	Difficult	Poor	Excellent	Moderate	Furniture, bench tops, fencing posts/poles, heavy construction and internal flooring
Eucalyptus leucoxylon South Australian blue gum	Difficult	Poor	Excellent	Few	Fencing posts/poles. and preservative treated timber
Acacia decurrens Early black wattle Acacia mearnsii Late black wattle	Excellent	Excellent	Good	Few	Tanning bark, fencing posts/poles, and preservative treated timber
Acacia dealbata Silver wattle	Excellent	Excellent	Good	Few	Panelling, furniture, veneers and preservative treated timber
Casuarina cunninghamiana River she-oak	Good	Poor	Excellent	Few	Furniture, panelling and fencing posts/poles
Casuarina glauca Swamp she-oak Casuarina obesa Swamp oak	Good	Poor	Excellent	Few	Fencing posts/poles

 

Species	Site	requirements	Species	attributes
	Minimum rainfall	Soil type	Growth rate	Frost tolerance	Salt tolerance	Ability to coppice
Eucalyptus occidentalis Swamp yate	350mm	Prefers sandy clay flats but tolerant of poor drainage, drought and salt	Moderate	High	High	Good
Eucalyptus cladocalyx Sugar gum	450mm	Prefers sandy clay loam with moderate drainage	Moderate	Low	Low	Excellent
Eucalyptus globulus Tasmanian blue gum	700mm	Prefers heavy loam clay but grows on a range of sites	Fast	Moderate	Low	Excellent
Eucalyptus camaldulensis River red gum	600mm	Tolerant of a wide range of conditions especially waterlogging and salinity	Slow	High	High	Good
Eucalyptus leucoxylon South Australian blue gum	450mm	Prefers moist sandy soil	Moderate	High	Moderate	Good
Acacia decurrens Early black wattle Acacia mearnsii Late black wattle	500mm	Tolerant of poor drainage, will grow on most sites but prefers sandy clay loams	Fast	Moderate	Low	No
Acacia dealbata Silver wattle	600mm	Prefers deep clay loams in valleys	Fast	Moderate	Low	No
Casuarina cunninghamiana River she-oak	500mm	Prefers deep sandy or gravelly soil	Moderate	Moderate	Moderate	No
Casuarina glauca Swamp she-oak Casuarina obesa Swamp oak	400mm	Prefers flat, wet, clay loam soils	Slow	High	Very high	No

* Growth Rates for firewood production: Fast 10 -15 years, Moderate 12- 18 years, & slow 15 – 20 years.
^ Species that re-shoot (coppice) readily should be chosen if a long-term enterprise is planned as there is no need to replant after harvest.
Adapted from Bird (2000), Sonogan (2002) and Measki (2003).

Stocking

The stocking rate at which trees are planted (commonly expressed as trees/ha) influences the volume of wood produced and the rotation length or time between harvesting operations.  Optimum stocking is mainly determined by annual rainfall, but other influences include species, soil type, site preparation and ongoing management.

Table 2 ‘Estimated production for firewood woodlots’ is a guide to choosing the optimum stocking rate based on annual rainfall.

Table 2: Estimated production for firewood woodlots

Estimated yield at maximum rotation length (dry tonnes/ha)

Annual rainfall (mm)	Stocking         (stems/ha)	Rotation length (years)
350-550	833 (4 m x 3 m)	10-20	40-160
550-750	1000 (4 m x 2.5 m	8-15	60-180
750+	1333 (3 m x 2.5 m)	7-12	60-240

Adapted from Primary Industries SA (1995)

Management

The general management of trees established for timber production is detailed in the previously mentioned PIRSA Forestry Fact Sheets.

Growers sourcing firewood from first thinning operations (at age 5-6) in sawlog plantations may only produce small quantities of firewood per hectare as tree diameters will be quite small. Subsequent thinning operations (from age 10) will produce more.

Harvesting

Trees can be harvested for firewood once they meet market specifications and/or demand.  Methods for harvesting firewood will vary depending on the scale of operation.

Large scale production (> 15 hectares)

This involves:

• mechanised felling,
• debarking and delimbing,
• forwarding or skidding to the plantation edge,
• cutting to length on site or at a merchandising yard.

The amount of wood harvested ranges from 20-35 green tonne/hr/machine depending on the size of the trees. Harvesting costs are $17-$22 per green tonne (2002) and are at their lowest when piece size is large, volumes per hectare are high, and access is easy. Common methods of cross cutting tree lengths into firewood billets (chainsaws and saw benches with circular blades) may be inefficient. Specialised firewood mills, such as the Hakki Pilke (see Figure 1) are powered by a tractor and capable of cross cutting logs to selected lengths and splitting them. Processed firewood may be stored at the point of production or a central point until dry and then transported to a wholesale firewood yard, or direct to customers. 

 

Figure 1 Processing logs using the Hakki Pilke firewood mill

 

Medium scale production (5-15 hectares)

 

This involves trees being felled, branches manually trimmed, and the tree docked into manageable lengths by a chainsaw. Without a mechanical system, bark removal is time consuming and costly. It is therefore recommended that logs be extracted from the forest and stacked for drying for several months to assist in bark removal prior to cross cutting and splitting. The FransgÂrd hydraulic forestry tong (see Figure 2) is an attachment for a farm tractor to aid in log extraction. As for large scale production, cross cutting is most efficiently carried out at a mill. Medium scale producers generally sell their firewood to a wholesaler.

 

 

Figure 2 Extracting logs using the FransgÂrd hydraulic forestry tong tractor attachment

 

Small scale production (< 5 hectares)

 

This involves firewood being produced at the stump and loaded directly onto a trailer or truck. Cross cutting is carried out with a chainsaw, and as for medium scale operations it would be best to fall trees several months prior to cross cutting so that bark separates from the wood during drying. Small-scale producers usually sell direct to the consumer, rather than sell to a wholesaler.

 

Harvesting of timber products is commonly expressed as green weight, whereas firewood production is ‘usable dry tonnes’.  To help understand the correlation, approximately 50% of the weight of green wood is water and usable firewood has a moisture content of 20%. Therefore the amount of usable firewood produced is approximately 60 to 80% of the green weight of the harvested timber.

 

The time taken to dry firewood will depend on the size of the wood, particularly its thickness, and how it is stacked. Logs stacked in the open take about a year to dry to a condition suitable for burning, while wood cut to firewood length will dry in less time, especially if stored in a dry and well ventilated shed.

 

Marketing

 

Plantation grown firewood is increasing in popularity due to its ‘environmentally friendly’ image.  This helps when competing with more traditional firewood species and sources that are currently sold in regional centres, or in Adelaide and Melbourne.

 

In the South East, sugar gum has great potential because it grows well in a plantation setting and has excellent coppicing abilities.  It is a marketing success story in Melbourne wood yards where it is now retailing at the same premium price as well known species such as yellow and grey box. In addition, a number of Tasmanian blue gum woodlots are nearing harvestable age in the South East.  Small woodlot owners should consider cooperative harvesting and marketing operations with other landowners in the district. Table 3 contains indicative retail prices of firewood at merchants’ yards for Adelaide, Adelaide Hills and Melbourne markets.

 

Table 3 Indicative prices of firewood at merchants’ yards for June 2002

Firewood species

Location	Price ($/dry tonne)
Adelaide, SA	$170 - 192	Predominantly red gum; other species include SA blue gum, yellow box, grey box and she oak
Adelaide Hills, SA	$135 - 192	Red gum, pink gum, SA blue gum, sugar gum and mallee stumps and roots
Melbourne, Vic	$160 - 185 $162 - 180	Yellow box, sugar gum Red gum

 Source: Bhati (2002)

 

Product specifications for wood yards

• Moisture content - less than 20% (common test is banging two pieces of firewood together – a bright sound indicates dry wood, whilst a dull thud indicates green wood).
• No bark persisting on wood (usually indicates unacceptably high moisture content however, sugar gum is an exception as bark may still persist on dry wood).
• Preferred dimensions 250-300mm in length (ensures suitability for all heating appliances) & maximum width for split and unsplit wood is 150mm.
• Wood may be delivered in log length or firewood length, split or unsplit depending on the merchant’s preferences.

References

 

Bhati, U.N. 2002. ANU Forestry Market Report. June, No. 20.

 

Bird, P.R. 2000. Farm Forestry in Southern Australia: a focus on clearwood production of specialty timbers. The State of Victoria, Department of Natural Resources and Environment.

 

Measki, B.(2003) Farm Forestry Species for South West Victoria.

http://www.dpi.vic.gov.au/dpi/nreninf.nsf/LinkView/56F210E296F9F3EACA256C19000DDD315F35DFAFEA9EE75E4A256DEA00276C0F

 

Primary Industries, SA Government 1995. Farm Trees for the Mount Lofty Ranges. pp 97-104.

 

Sonogan, B. 2002. Plantation Grown Firewood for Home Heating! What are the Obstacles? Agroforestry News, Autumn, pp 16-17

 

For further information contact PIRSA Forestry

 

Disclaimer: While this publication may be of assistance to you, the Government of South Australia and its officers do not guarantee that it is without flaw of any kind or is wholly appropriate for your particular purpose. The Government therefore disclaims all liability for any error, loss or other consequence that may arise from you relying on any information in this publication.

Last Revised January 2010