A forestry experiment forgotten for 30 years has delivered a surprise about carbon storage. Researchers revisited the Silvicultural Systems Project at Tanjil Bren in Victoria’s mountain ash forests. The experiment was set up between 1987 and 1989. It compared clearfelling, patch clearfells and heavy thinning, where 50 to 70 per cent of trees were removed. When scientists returned in 2014, the thinned sections stunned them. The trees left standing had grown enormous. The largest averaged over a metre in diameter at chest height. That is about 20 per cent bigger than trees in untouched control areas. More remarkably, the thinned stands had stored as much or more carbon in their wood as the unharvested forest. In 30 years, they had recovered all the carbon removed during harvesting. The findings have big implications. Bigger trees resist fire better and form hollows that endangered species need. Camera traps found Leadbeater’s possums in every treated plot, but in none of the unharvested areas. The researchers say no single approach suits every forest goal.