In Victoria aerial seeding was developed in the early 1960s by Grose et al.[4] for large areas where seed tree regeneration after clear-felling would have been inadequate. To enable delivery of the very small seed to be properly controlled it was necessary to increase its weight by coating with kaolin and an adhesive. To increase germination efficiency an insecticide and a fungicide were incorporated, although the latter was subsequently dropped after some years as it was shown to inhibit seedling growth. The aerial sowing technique proved to be very successful and many thousands of hectares of forest in several States have been treated in this way. For small isolated coupes some use has been made of helicopters. Because of the high labour content in eucalypt seed collection its cost has increased markedly, a factor which now has to be offset against the advantages of aerial seeding compared with ground seeding or planting seedlings.

Silvicultural treatments to improve forests by thinning and logging by clear-felling have both been greatly facilitated by the introduction of the chain saw, the crawler-tractor and the rubber-tyred skidder. Their economics depend very much on the availability of profitable uses for all the wood removed, not only the sawlogs but also the defective trees and the thinnings. Where such outlets are not available treatments are now tending to be scaled down or even eliminated, to the detriment of the forest as a sustained yield resource.

Timber production has traditionally been the major objective of the State forest services in their management of native forests. They have, however, to an increasing extent pursued this as part of a 'multiple use' policy, first formulated in the early 1900s, which recognizes that it can be integrated with other uses such as grazing, water and soil conservation, recreation and wildlife habitat. Since the latter part of the 1960s, however, there has been in Australia, as in other countries, a new wave of concern for native forests placing greater emphasis on non-timber values and in particular the conservation of landscape, flora and fauna habitat and water and soil values. This has led to loss of productive forests to national parks and the like where logging is not permitted and the imposition of more stringent controls where it is. Of the native forest area in 1985 (41 million ha) 4.9 million ha was in the former category, an increase of nearly 3 million ha since 1975. Some of the implications of these new policies for plantation establishment, harvesting and sawmilling are discussed in later sections.

Australian Academy of Technological Sciences and Engineering