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 following PIRSA Forestry Fact Sheets:

Growing trees in the Upper South East

Growing trees in the Lower South East

Establishing, Managing & Harvesting Farm Forestry 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 (SA).

 

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 depending on annual rainfall.

 

Table 2: Estimated production for firewood woodlots

 

Annual rainfall (mm)	Stocking (trees/ha)	Rotation length (years)	Estimated yield at maximum rotation length (dry t/ha)
350-550	833 (4mx3m)	10-20	40-160
550-750	1000 (4mx2.5m)	8-15	60-180
750+	1333 (3mx2.5m)	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 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 would be most efficiently carried out at a mill. Medium scale producers generally sell their firewood to a wholesaler.

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

 

Small scale production (< 5 hectares)

This involves firewood being produced at the stump and loaded directly on to a trailer or truck. Cross cutting would be 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, 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.

 

 

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