This Forest Survived a Megafire

[NickB79]

https://nautil.us/this-forest-survived-a-megafire-1236277/?utm_source=firefox-newtab-en-us

Five miles down a bumpy dirt road in Plumas National Forest, at the northern end of the Sierra Nevada mountain range, lies a paradox. On one side of the road, a scorched wasteland of burnt toothpicks covers the Earth, a stark reminder of the devastating Dixie Fire that swept through this area four years ago. Not a single living tree remains. But a few hundred feet away, a stand of hardy, healthy ponderosa pines shoot into the sky, their branches reaching toward the sun. Small burn marks on the trunks of these trees are the only evidence of that brutal fire, which devoured nearly 1 million acres across five counties in 2021, making it California’s largest single wildfire to date.

snip

The most commonly used methods to protect forests against megafires today include either thinning the trees or setting prescribed burns, and sometimes both. But some have begun to question whether controlled burns are effective during increasingly intense droughts, given the risks that such burns could spiral out of control. And while plenty of research has looked at how thinning and burns influence fire severity, few efforts have studied how these treatments affect the longer-term survival of individual groves of trees.

When the researchers analyzed the data from their plots, what they found is that thinning trees alone is not much better than a total lack of forest management. This is possibly due to the fact that some methods of tree thinning actually can increase fire risk because they leave behind dry branches that serve as tinder. But prescribed burns clear away that fuel, making a combination of thinning and burning the winning approach, the researchers found. It didn’t matter if the combination of treatments had been tried five years or 20 years prior. When thinning was followed by burning, the researchers saw much lower levels of both tree mortality and canopy torching. To save trees, it appears, you have to both cut them and burn them.

Please note, this doesn't say LOGGING is effective at preventing forest fires (as those on the right like to claim). The vast majority of trees removed in a thinning operation aren't log-quality; they're the spindly, closely packed ones. You actually leave the best log-quality trees behind to act as nurse trees later on.

[Bernardo de La Paz]

1. Fascinating! Good find. . . . . nt

[Srkdqltr]

2. How do you burn without burning all? I don't understand.

[NickB79]

4. Carefully

By thinning the forest of small trees, you prevent flames from being able to reach the canopy of the larger trees.

Then you have to set controlled burns when there have been decent rains so that humidity levels aren't too low, as well as watching winds and temps. There are always risks of fires running out of control, though.

[Srkdqltr]

7. Ok. I see.

[hunter]

3. Immigrants from Europe might have learned how Native Americans were managing forests...

... but they weren't paying attention as they were too busy killing both.

[eppur_se_muova]

6. Ditto grasslands. nt

[Srkdqltr]

8. Thats true.

[eppur_se_muova]

5. Hmmm ... no mention of these well-known phenomena ...

Thick bark.

Trees in fire-prone areas develop thicker bark, in part, because thick bark does not catch fire or burn easily. It also protects the inside of the trunk, the living tissues that transport water and nutrients, from heat damage during high-frequency, low-intensity fires. Ponderosa pine (Pinus ponderosa, also commonly known as the bull pine, blackjack pine or western yellow pine) is a great example. This signature tree in the western United States has a thick and flaky bark, sometimes compared to pieces of a jigsaw puzzle, which perfectly withstands a low-intensity, surface fire. The species also drops lower branches as the trees grow older, which helps prevent fire from climbing up and burning the green needles higher up the tree.

Fire-induced sprouts.

This fire-survival strategy allows for the complete destruction of above-ground growth. Typically, species that regenerate by re-sprouting after they’ve burned have an extensive root system. Dormant buds are protected underground, and nutrients stored in the root system allow quick sprouting after the fire. Shortleaf pine (Pinus echinata, also occasionally called southern yellow pine or the shortstraw pine) employ this technique.
***
more: https://www.nationalforests.org/our-forests/light-and-seed-magazine/how-trees-survive-and-thrive-after-a-fire


Add NickB79's remark in post #4, and it sounds like Ponderosas interspersed with other species which do not shed lower limbs would be more prone to crown ignition than Ponderosas in more homogenous groves, and thus less likely to survive a fire. So the isolated grove referred to in the OP sounds like it might be a common phenomenon.