Firewood Growing in the Adelaide Hills and Fleurieu Peninsula

This Farm Forestry Note provides an introduction to firewood growing within the region:

• the species to grow

• planting designs

• harvesting

• marketing.

The Adelaide Hills and Fleurieu Peninsula are well suited to firewood production because of:

• productive growing conditions

• proximity to the Adelaide market

• scope for plantings to address landcare concerns

• benefits when integrated with conventional farm pursuits.

A firewood enterprise offers several advantages:

• firewood production is quicker to generate returns than sawlog production — generally 10–12 years from planting to harvest

• you can add value by harvesting and marketing your own resource

• you can produce firewood on sites of lower productivity than required for saw log production

• once established there is little need for further management such as pruning and thinning — you only need to sit back and watch it grow

• if you use species that coppice from the cut stumps you can avoid the expense of replanting a second crop.

Wood quality:

The majority of firewood burnt currently still comes from old slow growing trees — mallee, red, pink or blue gum, sheoak or box species from Victoria and New South Wales. Their slow growth rate yields dense slow-burning firewood. They are however a finite resource. Market adjustment and education will be needed over the next few years to encourage acceptance of plantation grown firewood. This faster grown wood will still burn well but will not have the slow burning characteristics of old growth trees. The heat yield or calorific value per tonne will be the same; it’s just that your firewood stack will be a little larger!

Prospects for the future:

The last survey undertaken by the Australian Bureau of Statistics (1989) found that one in five households used firewood as their main form of heating and that 415 300 tonnes of firewood was used in South Australia in 1989. While this figure was for the whole of South Australia the largest proportion was presumably consumed in Adelaide. If supplied from plantation grown firewood on a sustainable yield basis with a 10 year rotation, this would require a plantation area of around 27 000 hectares. Although gas heating is relatively cheap and convenient, firewood consumption continues to rise. However, this does not mean the price will rise under the law of supply and demand. The home heating market is notoriously fickle and consumers frequently switch as one form or another goes out of favour or becomes more expensive. This was highlighted by the switch from oil heating in the 1970s.

Firewood prices — and hence returns to the grower — are therefore capped by the costs of alternative heating fuels. If environmental legislation were passed requiring reduced smoke emissions firewood could quickly go out of favour. However, the industry hopes that the development of more efficient burning systems and education programs on efficient use of slow combustion heaters may avert the need for legislation. The fact is that growing firewood is potentially very profitable but there is some uncertainty and the market risk requires individual consideration.

Firewood species should:

• be quick growing

• be able to coppice

• give a dense wood

• be easy to split

• burn well leaving little ash

Design:

Firewood is best grown in woodlots or belts of trees at least six rows wide. Tree planting density, growth rate and species selection are largely governed by soil moisture availability and rainfall. Where rainfall is greater than 600 mm then 1100– 1600 trees per hectare are desirable. On drier sites, (450–600 mm rainfall) 800 to 1100 trees per hectare are a better proposition. These initial stocking rates allow for seedling mortality of up to 10% without requiring any subsequent replanting, except perhaps where a number of consecutive trees fail within a row or adjacent rows.

The most common mistake made in establishing a woodlot is to plant the trees too close together. This means high seedling costs, excessive competition between trees for moisture and nutrients, resulting in many spindly stems too small for harvest and sale.