Ecological Thinning: Logging by Stealth?

The new forest Management Plan, 2024-2033, includes so-called ‘ecological thinning’ of regrowth Jarrah, Karri and Marri of up to 8,000 hectares per year. So far Bridgetown Greenbushes Friends of the Forest had not paid much attention to this but suddenly we find it on our doorstep.

Thinning is already well under way in 350 Ha of Gordon Block, about 20 km south of Karri Gully. Closer to home it will also happen this year on 400 Ha (4 sq miles!) of the Gregory Block, west of the Bridgetown Jarrah Park and Dalgarup National Park on the Brockman Highway. It is also scheduled in 520 Ha of Yardup block, immediately west of ‘our’ Warrup Block.

Thinning is a silvicultural procedure usually aimed at boosting the production of desired species by reducing competition. That is not the intent in our forests now.

The stated aim is to protect forests against water stress - death in drought. We have just had examples of tree death due to the 7 month rainless spell since September.

Thinning can be non-commercial, and significant funding would need to be provided for this. However the Forest Management Plan proposes commercial thinning, where small, mostly low grade karri or marri logs suitable for chipping or jarrah logs suitable for firewood or fuel wood (by users such as SIMCOA) are removed for sale. Contract management, planning and operational support would be provided by DBCA. This means that, contrary to the State Government’s announcements, commercial logging will not have ended.

Why don’t we like “Ecological Thinning”?

Long term BGFF Member Dr Beth Schultz AO responded to the Draft Plan that thinning of our regrowth forests is not necessary because they self-thin over time. It is counterproductive because it will not increase streamflow. It has adverse impact on tree growth and health through soil compaction and disturbance and increased spread of Phytophthora (“dieback”) and marrri canker. It releases large amounts of stored carbon and increases, not decreases, the flammability of the forests.

The thinning works are done by machine. In addition to the thinned coupe areas, compacted areas of log landings and extraction tracks add more than 12% of the coupe area. Recovery from compaction may take more than 50 years.

Thinning increases, not decreases, the fuel load and the flammability of the forest. It leaves large amounts of logging debris on the ground and dead trees in the forest if the thinning is non-commercial.

Commercial thinning, followed as it is by burning, results in a massive amount of atmospheric carbon and a response of ‘fire weeds’, native and introduced, that have a higher flammability than the replaced woody species.

BGFF, with its Nannup friends, plans to monitor very carefully the Gregory Block thinning.

Richard Wittenoom, with appreciation to Beth Schultz