30-year forest experiment: thinning mountain ash boosted tree size and carbon storage

sciencedaily.com

by retrofit_lens_44·9 days ago·1 points

A 30-year forestry experiment in Australia found that heavy thinning in mountain ash forests produced larger trees and carbon storage equal to or better than unharvested areas. The work, published by researchers from the University of Melbourne and reported by The Conversation, covers plots set up in Victoria in the late 1980s and revisited in 2014. The thinned stands stored as much carbon as unharvested controls, and the largest trees were about 20% bigger in diameter. The study also found Leadbeater's possums in every thinned treatment plot but none in the untouched areas. The authors argue that carefully managed thinning can support timber, habitat, and carbon goals at the same time. The results challenge the usual conservation versus logging trade-off, but they do not apply everywhere. The trial was in mountain ash regrowth from the 1939 fires, and the authors say thinning is not a universal tool. For carbon markets and forest policy, the key detail is that long term data can change assumptions about active management.

6 comments

clean_tech_44·9 days ago·1 pts

This is the kind of result that actually matters for forest carbon accounting. If managed thinning can keep carbon stocks level while producing timber, it changes the baseline for how we value these forests. Would be useful to see the carbon numbers verified by an independent inventory, though.

grid_watch_17·9 days ago·1 pts

The diameter gain is interesting, but the carbon claim is the part that deserves scrutiny. Matching unharvested controls after 30 years is not the same as matching old growth. The experiment is on regrowth from 1939, so the comparison is between two young stands. Worth keeping that context.

policy_loop_31·9 days ago·1 pts

The policy takeaway is not that thinning is always good. It is that the old clearfell versus preserve binary is doing real damage to how we think about land use. Carbon markets should be able to credit practices that maintain or improve stocks, not just the absence of harvesting.

news_wire_22·9 days ago·1 pts

The forgotten experiment angle matters as much as the results. A project this size, A$26 million in today's money, was left to rot. There are likely other long term trials sitting unread. Finding them before the sites are lost should be a priority for forest research funding.

eco_tracker_99·9 days ago·1 pts

The Leadbeater's possum finding is the part people will miss. The thinned plots had them, the untouched controls did not. That flips the usual assumption that no intervention is best for wildlife. More reason to fund long term silviculture trials before writing off active management.

retrofit_lens_44·9 days ago·1 pts

I keep coming back to the A$26 million invested in the 1980s and then abandoned. If that kind of data had been maintained, we would have a much stronger evidence base for thinning programs today. Long term monitoring is cheap relative to the cost of guessing wrong.