Most of the mechanized harvesting equipment in use is of highly specialized overseas design and manufacture. A local innovation that has become popular, however, is the adaptation of the common tracked excavator for the stacking and loading of logs by the replacement of its bucket with an hydraulically-operated grab. Apart from having a capital cost advantage over many specialized machines, such a unit can, in favourable locations like plantations, operate over a large radius without moving position, thereby minimizing ground disturbance and increasing output. It has recently also been adapted to take felling heads and processors.[46]

The use of cable or skyline logging, which has been practised to a very limited extent and in various forms in Australia for many years, has recently found favour again with the introduction of new commercial equipment of improved design from overseas. It is now in use in both pine plantations and productive eucalypt forest in steep country and if overseas trends are followed this seems likely to increase. Reduction of soil disturbance and compaction are important advantages that this method offers.

In pine plantations maintenance of soil productivity -and sometimes also water catchment values -are the main environmental concerns during harvesting and soil compaction and inappropriate disturbance must be avoided. In native forests, however, retention of landscape values and fauna habitat have also become matters of considerable concern to many people, especially since the introduction of clear-felling in the 1960s. Forest services have responded by developing harvesting strategies that minimize the visual impact of clear-felling and preserve some fauna habitat. Logging coupe sizes are now generally smaller and of shapes that tend to harmonize with the landscape. Some trees are left for nesting as, too, are corridors of forest to enable fauna to move to non-logged areas and a reasonable time interval is often allowed between the harvesting of adjacent coupes. Post-logging restoration of the coupes is generally required, involving re-establishment of contours, erosion prevention, stream clearing and dispersal of bark and debris.

Australian Academy of Technological Sciences and Engineering