GROWING AND HARVESTING TREES

Early days axes, cross-cut saws

Harvesting of the native hardwood timbers in Western Australia commenced with the first settlement of the Swan River colony in 1829. The local eucalypt species such as jarrah (Eucalyptus marginata) and tuart (Eucalyptus gomphocephala) are large trees with high to very high wood density, and weigh many tonnes. Felling trees with axe and crosscut saws would have been a real challenge to the early settlers, who were used to medium density European timbers.

Chainsaws were developed in the 1940s, and initially were very heavy, requiring a two-man operation, and had very poor ergonomics. The modern chainsaw is very efficient, and is used for felling and docking (i.e. cutting logs to length) all large trees. Mechanical harvesters are generally used in plantations, and are being used increasingly in regrowth eucalypt forests.

Bullock teams, railways, steam tractors, modern tractors

In the early days, the logs would be sawn where the trees were felled, by digging a pit underneath or rolling the log over the pit on supports, and then using cross-cut saws. As the sawmilling industry developed, the logs were hauled a comparatively short distance to a sawmill established in that logging area. Bullock teams were used initially to take the logs to the site, and in the later stages a large wheeled arch or whim was used to lift the front end of the log and make snigging easier. Railways were built because of increased distances to the mill, using narrow gauges, with timber rails except on bends where steel rails were essential. The bullock teams were still used to haul logs to railway sidings.

In the early 1900s steam tractors were developed, big machines with rear driving wheels perhaps 3 m in diameter. The modern tractor became the major means of hauling logs after World War 2, until the development of the forwarder that picks up logs and delivers them to landings.

Mechanical harvesters

Mechanical harvesters are used almost exclusively in both softwood and hardwood plantations, and will have increasing use for harvesting small trees in native regrowth forests. The vehicles are generally tracked, with a computerised harvesting head on a boom. The trees are cut with either hydraulic shears or with a chainsaw attachment. In softwood plantations the method used is to remove all trees in each fifth row, and the harvester can then reach in two rows on each side of that row. A forwarder with a hydraulic crane then collects the logs and transports them to log landings.