Management options:
Specialist woodlots
Plantings which are specifically established and committed to the growing of firewood. These are commonly established at 1100–1600 trees/ha, with a row spacing of 3–3·5 m enabling tractor access.
Integrated firewood sawlog production
The trees are principally planted for longer term sawlog production. The stand is thinned, removing trees of poor form and vigour at a time when they are large enough for firewood. Firewood is produced at the expense of achieving maximum sawlog growth rates, as trees of low quality are maintained on the site until they reach commercial firewood size. In doing so they compete with the sawlog crop for limited site moisture, nutrients and sunlight.
Care is essential during thinning operations to avoid damaging the potentially high value sawlogs in the remaining trees.
Low intensity direct seeded woodlots
Selected Firewood Species for the local region matched against suitable site types (Yield in dry tonnes/ha on a 10 year rotation)
This system typically uses local species which are established by direct seeding. It is valuable in satisfying conservation and habitat values in addition to producing a commercial crop. This regime is best suited to the supply of personal firewood or large low yielding plantings in lower rainfall situations. Direct seeding of more productive species in higher rainfall zones allows large areas to be established at lower cost than planting seedlings. To optimise production with direct seeded areas extra work is needed to space the stand by thinning and infilling.
Where to Plant?
Three different approaches to harvesting firewood
As with all crops, the better the site the better the trees. Shallow, stony sites produce slow growth rates, resulting in a long wait for relatively small timber yields and a poor return on investment. You may be tempted by the low agricultural value of these sites but recognise their production limitations.
If you combine shelter and firewood in a belt, plan your harvesting carefully so some shelter remains at all times. The cropping must be part of a comprehensive dynamic shelter system.
If you have saline or wet paddocks by planting interception belts upslope of the problem area you will generally yield high volumes of wood and help lower the watertable.
When is it time to harvest?
The most efficient time to harvest for maximum volume of wood is when the average rate of growth of the stand is at its maximum. This is when the current rate of growth becomes less than the average rate of growth since planting. (see fig graph: Time versus growth , CAI, MAI)
This is only a guide and the stems must be of appropriate diameter — neither too skinny nor so large that they require splitting. However, you may have personal or market reasons for cutting firewood earlier or later than the point of maximum
Although growth can be followed closely by measuring the trees you may not feel it is worth the effort and base your “time to harvest” decision on the age and size of the trees.
Typically the rotation length will be 10–12 years in areas receiving greater than 600 mm annual rainfall and 2–3 years longer on drier sites or those with poor soils. The total volume of wood produced is given by the following equation:
given in dry tonnes/ha/year for the selected species and matched to an indicator site quality species in the table above.
Total Volume = Rotation length in years x Mean Annual Increment* average wood production.
