Reply from Cal Wettstein on Bark Beetles and Fire

cal wettstein

Cal is retiring fro the Forest Service; currently his is the Acting Deputy Forest Supervisor on the White River, so you might want to send your greetings to him.. Here’s an article about him, when he was bark beetle incident commander (you may have to answer some strange questions to get to the content).

Below is his answer to the question Andy Stahl raised here, regarding a quote from Cal in this story.

On the BB fire thing, first, I won’t miss the political arguments over it….. but really, I looked at the NASA clip and the naysayers (ie Veblen, Kulakowski, etal) continue to miss the big picture. We’ve been very clear that in pure lodgepole pine, during the red-needle stage ignition is easier and we can get flashy crown fires, but they only last one burn period—there’re no heavy fuels to carry fire for very long. The BB fire connection is several decades out. The dead trees fall over 15-20 years (hopefully they’re not disputing the effects of gravity), creating a heavy fuelbed of 60-80 tons per acre. The next forest grows up through that fuelbed and the combination of heavy down fuels, residual mature trees that weren’t killed by bugs, and regeneration that will serve as ladder fuels, set the stage for intense large scale fires—not over the next few months or years as implied by the NASA piece, but over decades—40-50 years. I know the intent of these ongoing arguments is to keep management in check in the short term—so we don’t overdo the knee-jerk reaction to red trees, but the work we’ve been focusing on in the WUI is aimed at much longer term. Andy needs to look at the longer term. Bottom line is, despite high-priced NASA landsat analyses or convoluted GIS exercises, we know from real-life fire experience that a fuel model with 60-80 tons of heavy fuel per acre is going to be problematic when it eventually burns—especially in and around homes and infrastructure.

Well, I could go on and on but I’d be wasting breath…. So I’ll just say that I would never assert that BB’s cause large scale intense fires—BB’s are just one integral part of numerous extremely complex systems that also include fire.

Note: what Cal says is not very different from what I’ve been saying and what we told the local Colorado scientists at various meetings. So possibly some folks didn’t listen to what we said, or they didn’t believe us, or other places are very different from Colorado. Each possibility raises a variety of intriguing questions, IMHO.

7 thoughts on “Reply from Cal Wettstein on Bark Beetles and Fire”

  1. Cal has said the same thing to me many times during interviews. My question is, how long do those down trees stay viable as highly flammable fuel? Are there any peer-reviewed studies showing that, in fact, the downed beetle-killed trees are a major fuel source after 20-30 years? Does it depend on aspect and elevation? In somewhat wetter areas, it appears to me, based on personal observation, that the downed trees get mushy (I know that’s not a technical fire term) in that timespan. Perhaps in lower elevation on drier slopes, they might stay viable as a fuel source a bit longer.

    • With all due respect, and as one who worked on the White River in timber well before Cal arrived (1979), controlling a fire burning under drought and windy conditions in a mature lodgepole pine forest, regardless of understory fuel loading, is a fool’s errand. The understory fuel loading isn’t going to make any meaningful difference when it comes to fire suppression. Sit back, roast marshmallows, and keep people safe. As any number of FS studies have shown, the fate of homes will depend not upon what Cal, et al., do on public lands, but on the home ignition zone and construction materials.

      In Cal’s post, there’s also a bit of revisionist history. Here’s what Cal had said originally in the story to which I linked:

      When pine beetles take over a forest, fire is typically not far behind, said Cal Wettstein, incident commander with the Rocky Mountain division of the Beetle Incident Management Organization.

      “When trees die, they go through a natural process of drying” — leaving them vulnerable to fire — “and eventually falling,” he said. “When beetles get into a forest, they essentially shortcut that first stage.”

      Now Cal is saying that the dead trees affect fire 40 to 50 years after dying, which hardly sounds like the “not far behind” and “shortcut” messages in the story as reported.

      I’ve not seen any studies that substantiate Cal’s assertion that fire is more highly correlated with pine beetle-killed forests, regardless of how long since the beetles passed through the neighborhood. That’s all the NASA study looked at — geographic correlation between burns and beetles — and it found none.

      A corollary to the NASA study is that suppression actions and fuels treatment simply haven’t made much of a difference on a big landscape-level. In other words, about 4-6 million acres burn annually nation-wide; more during droughts and less during damps, no matter how much money we spend on fire suppression or pre-suppression fuel treatments.

  2. In an attempt to respond to Bob B.s question, I believe the downed dead timber rot cycle is heavily related to the snow depth (ie, elevation, snow zone, aspect) and duration that these trees are covered with snow. If they are jackstrawed, very thick and many boles are 6-10′ above the forest floor, they stay hard and firm and more combustible for many more years than if they are in touch with the duff and molds, etc. That is my experience.

    And I wish we could discuss fire hazards or intensity of burns without adding the WUI/risk to homes factor. That is another, separate issue. I suspect it is very rare to find homes or housing tracts right up against dense stands of LPP with tons of down LPP in the understory. In those extreme, very rare situations where this might occur, the WUI high-hazard zone might need to be expanded a bit beyond what is “normal”.
    We keep mixing our apples with our oranges in these discussions. Talking about fire severity in the forest miles from town is one issue. Discussing the 1/4 mile immediately adjacent to structures is a different issue. We must clarify what we are discussing and stay on track!

    • I tend to think that it is impossible to separate forest issues because, in the end, all the issues must be re-combined and applied in a site-specific way. Snag patches and re-burns are real and persistent dangers, often ignored in public land discussions. Here in the Sierra Nevada, fires (both human and natural ignitions) are a reality that cannot be ignored. Fires here are more fuels-driven. Bark beetle mortality merely adds to the fuels loadings. Studies rarely include fires from ALL sources, and their conclusions rarely apply to many real-world forests.

    • Ed, I agree with you about snow, but also like any fungal activity it depends on very local moisture and heat conditions through time. Like warmer and wetter is always better than colder and drier.

      I also agree with you about helping to stay on track by talking about specific situations. I made a post with a table that might help that.

      In Colorado, I think we have quite a few WUI dead LPP projects, which is why I think the differences in our areas are so interesting. In fact, when I worked for the FS, we did a powerpoint for the RACNAC about the differences between Colorado and Idaho, which everyone might find interesting will try to find a copy online.

  3. Fires in the Sierra are “fuel driven”??? Are you saying that fuels are more critical than weather events? Of course, the amount and types of fuels influence the fire behavior and intensity, but I have yet to see any discussion with wildfire experts who put fuels at the top of their concerns. Climate change and extreme weather…yes

    Of course all these issues about fire and fuels and managment are eventually inter-related, but our discussions here seem to meander from some rather site-specific point or narrow research finding (or opinion) into other avenues that really don’t relate to the starting point of the discussion.

    If we are going to discuss WBP mortality (almost always on some remote, high-elevation ridgetop) don’t, please, digress into low elevation, WUI related arguments. Sometimes our discussions here degrade to the level of current rantings about “gun control” in the media. Illogical and confusing.

    • Ed, I think we digressed because the WPB litigation and my tracking down of Cal Wettstein, which I had agreed to do a while back when Andy posted the NASA article, occurred at the same time. I totally agree that the need for, utility of, and design of fuel treatment projects depends on local factors.


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