Silvicultural Systems Project (SSP).

The Silvicultural Systems Project (SSP) was a key research initiative that followed the release of the Timber Industry Strategy (TIS) in 1986.

Long running controversy about clearfelling of forests for sawlogs and pulpwood (woodchips), which was the dominant harvesting and regeneration system, led to the SSP to develop and evaluate alternatives.

SSP trials were established in mountain ash forests at Tanjil Bren in the Central Highlands, and mixed species coastal lowland forests at Cabbage Tree in East Gippsland.

Each trial area was about 10 ha and included several alternative silvicultural treatments including group selection with variable sized gaps and strips, shelterwood, seed tree and clearfelling. Burning and mechanical site preparation after harvesting were compared for each treatment .

A primary objective was to determine if alternative silvicultural systems could successfully regenerate eucalypt forests after harvesting.

The studies were probably the most comprehensive silvicultural and ecological studies undertaken in Australian native forests. The studies covered operational safety, economics, soils, tree growth, silviculture, water quality and biodiversity.

An interim progress report was prepared in 1990. Many other technical reports were prepared.

The SSP trials demonstrated that clear felling, followed by high-intensity slash burning and seeding, was the most operationally and economically effective, but alternative harvesting and regeneration systems were possible.

The studies also highlighted the importance of what I call the Silvicultural Trinity of S’s – being Seed supply, Seedbed and the subsequent Seasonal conditions for successful seedling germination, survival and growth.

The SSP trails were run in conjunction with a Value Adding Utilisation System Trial (VAUS) in East Gippsland to examine the silvicultural and environmental effects of harvesting pulpwood for woodchips to manufacture pulp and paper products.

The studies were intended to last for more than 50 years but were maintained for only 12. There have been some intermittent measurements, but SSP was wound down because of Departmental restructuring and funding cuts.

Ross Squire, (1990). Report on the Progress of The Silvicultural Systems Project, July 1986-June 1989. DCE. https://drive.google.com/file/d/1xorit838Q3wpS8Te98u45mQuwOV6o7B8/view