A forestry experiment in Australia's mountain ash forests, established in the late 1980s and then forgotten for years, has delivered a surprise. The Silvicultural Systems Project at Tanjil Bren compared clearfelling, small patch cuts, and heavy thinning against unharvested control areas. When researchers revisited the site in 2014, they found that the heavily thinned stands had produced remarkably large trees—the biggest averaged over a meter in diameter, about 20% larger than those in untouched controls.
Just as striking, the thinned stands had recovered all the carbon removed during harvesting and gained enough additional carbon to match or exceed the increase seen in unharvested areas over the same 30 years. Larger trees are more resistant to fire and more likely to develop hollows that provide habitat for rare species. Camera traps confirmed that Leadbeater's possums were present in every thinned treatment plot but absent from unharvested areas.
The results challenge the idea that conservation and timber production are always in conflict. The authors argue that carefully managed thinning can support wood production, carbon storage, and wildlife habitat at once—though they caution that it is not a silver bullet and should not be applied everywhere. They also stress the value of long-term experiments, many of which have been neglected or forgotten, and call for finding and funding them before their insights are lost.