Key Takeaways
- Thinning paid off in tree growth: Heavily thinned mountain ash stands (50% to 70% of trees removed in 1987) grew trees about 20% larger in diameter than unharvested controls after 30 years.
- Carbon fully recovered: Within 30 years, the thinned stands regained all the carbon removed in the original harvest and matched or exceeded the carbon in untouched forest.
- Endangered possum detected: Camera traps recorded the critically endangered Leadbeater’s possum in every treated plot surveyed and in none of the unharvested controls. The findings come from one site in one species of eucalypt.
Deep in Victoria’s Central Highlands, a set of mountain ash plots at Tanjil Bren sat in plain sight after active monitoring tapered off in the early 2000s. When researchers returned in 2014 and began full re-measurements around 2019, one treatment stood out: heavily thinned stands where 50% to 70% of trees had been removed back in 1987. Thirty years on, those thinned plots produced trees about 20% larger in diameter than unharvested controls and recovered all the carbon taken in the original harvest, ultimately matching or exceeding the carbon in untouched forest. Camera traps also picked up the critically endangered Leadbeater’s possum in every surveyed treatment plot, a result highlighted in a Forest Science paper published on 7/1/2026 and later summarized by ScienceDaily on 10/4/2026.
A forestry time capsule, opened with modern eyes
Long-term experiments are the kind of “infrastructure” tech loves, but ecology rarely gets to keep them running like a cloud service. That is why a rediscovery in Victoria, Australia has been pinging around US climate and land-management circles lately. A set of forest plots left quiet for years ended up carrying a clean, 30-year record of growth, carbon, and wildlife.
The project was the Silvicultural Systems Project, established between 1987 and 1989 at Tanjil Bren and Cabbage Tree Creek to compare regeneration methods, per two sites in Victoria. Tanjil Bren, the best-documented site in the later re-measurement, was dense mountain ash regrowth that originated after the catastrophic 1939 bushfires.
The experiment that went quiet, then came back
The setup reflected a government push in the mid-1980s to explore alternatives to clearfelling, with treatments that included traditional clearfells 250 to 350 meters wide, smaller patch clearfells 50 to 140 meters wide, and heavy thinning. Active monitoring stopped in the early 2000s, and the plots faded into institutional memory.
Researchers returned to Tanjil Bren in 2014 during a University of Melbourne teaching trip on native-forest silviculture, then started full new field measurements around 2019. The revisiting team included Kaitlyn L. Hammond (University of Northern British Columbia) and University of Melbourne researchers Craig Nitschke, Patrick Baker, and Raphael Trouvé.
Bigger trees, and a carbon surprise
The cleanest “wow” came from the heavily thinned stands, where 50% to 70% of trees had been removed decades earlier. After 30 years, those trees grew to be 20% larger in diameter at chest height than trees in unharvested controls, with some individuals exceeding 1.5 meters across (about 5 feet).
Then came the carbon accounting: within that same 30-year window, the heavily thinned stands recovered all the carbon removed in the original 1987 harvest, and accumulated enough additional carbon to match or exceed the carbon in unharvested forest. The peer-reviewed study, “Alternative Silvicultural Systems Maintain Multiple Values in Tall Eucalypt Forest,” was published July 1, 2026 in Forest Science.
Camera traps, a possum, and a caution for would-be copycats
Wildlife monitoring added a sharper edge. Camera traps recorded the critically endangered Leadbeater’s possum across every silvicultural treatment plot surveyed, but not in any unharvested control areas, according to a ScienceDaily summary. Larger trees resulting from thinning are also more likely to form hollows, a key habitat feature, and are more resistant to fire.
There is an important boundary on what this means for US foresters: the findings come from re-measurement at one main site, in mountain ash, a fast-growing eucalypt adapted to infrequent, severe bushfires. Still, as carbon markets and resilience planning ask for harder numbers, this kind of long-lived field dataset feels unusually “tech-like” in its value.
