It’s in our paper that just came out. See figure 4, positive interaction between tree height and HDW index causes sign to flip. Like I said, I’d want to understand it more, but this is just about the most detailed data we’ve ever had on these dynamics so I’d be surprised if it’s a total artifact

My hope is that this research can help us better balance the goals of providing a sustainable source of timber and reducing fire risk.

Fire is ultimately a contagious process. That means we need broad cooperation across ownerships to get on top of it. Logging is a part of the solution!

The real issue for me is that logging=bad ignores all the nuance. Sure, some logging is bad for fire, but other types of logging are critical for reducing severity. The timber industry has a clear fire problem (so does USFS, just a slightly smaller one), it also provides enormous value.

We also find that while big trees reduce the prob. of high-severity fire in mild weather conditions, they become a liability in extreme ones, increasing fire severity. I would want to understand that result more before basing policy on it, but nevertheless it suggests some complications.

Its complicated. We show conclusively that the increased risk of high-severity fire in industrial forests is the result of plantation-type structures, too many trees spaced too regularly. This suggests thinning (i.e. logging) and rx fire are needed across both private and public land.

@latimes.com

Hopefully, this research will help us strike a better balance between the sustainable production of critical wood products and the mitigation of fire severity risk in plantations.

Mitigating the severity of future fires requires a coordinated effort across ownership boundaries. In particular, strategies like mechanical thinning which reduce the density of trees and foster structural variability are critical.

Overall, the paper suggests that the forest structures created through plantation forestry -- dense, homogenous stands with high ladder fuels -- elevate the risk of high-severity fire. However, although public lands fared better in our dataset, they still have a massive fire severity problem.

This is an important result because it indicates that management practices which reduce tree density and ladder fuels, and increase variability, will remain effective even as extreme weather conditions become more prevalent under climate change. Indeed, these efforts will only become more urgent.

Critically, we also found that the effects of forest structure on fire severity were amplified in extreme weather conditions!

We found that fires were more severe in dense, spatially homogenous forests with high ladder fuels – characteristics more common on private industrial than adjacent public land.

Using this data, we examined: (i) which forest structures are most associated with high-severity fire; (ii) whether these forest structures are more common on private industrial land; and (iii) how extreme fire weather driven by climate change mediates the effect of management.

Using a unique airborne LiDAR dataset, we identified and mapped individual trees across 460,000 hectares in the Sierra Nevada, an area which subsequently burned in five large wildfires including the Dixie Fire, the largest single fire in California’s recorded history.

Brandon Collins, Michelle Coppoletta, Scott Stephens and I have been working for the past three years to understand a consistent, puzzling pattern in wildfire data: that fires are more severe on land owned by industrial timber companies than on land managed by public agencies.

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