Impacts of Fire Disturbance on Anthropogenically- Induced Vegetation Mosaics

This is a guest post from Derek Weidensee

If Derek Weidensee were writing for academic journals, he would probably title these photos the above. But he calls them “clearcuts don’t burn.”

Look at photo-39. It’s my attempt at objective reporting. It’s a clearcut that burned. You can see the burned part to the left of the green island. Of course, in 85% of the cases the fire stopped at the edge-stark contrast like-but where it did burn into the regen it soon dropped to the ground and piddled out.

(photo 39 is below)

From Derek:

I’ve spent the last four years photographing the phenomenon on 8 Montana wildfires. The “green islands” are regenerated clearcuts 20-40 years old. They are all of the 2008 Rat Creek fire and the 2000 Mussingbrod fire both west of Wisdom Montana.

If you’re into “google earth”, you can see the location and also another “striking visual” of the Phenomenon by typing the following latitude and Longitude into the “fly too” box. “45 44 56.65N, 113 44 10.71W”. Also try 45 41 34.44N, 113 45 13.15W.

I think you’ll find them interesting. In light of the MPB epidemic, I think it goes a long ways towards answering the question “does salvage logging mitigate fire hazard”. I’m certainly not saying you need to clearcut it all, but there is research that shows “strategically placed” salvage clearcuts on 20-30% of the project area can limit the spread of the fire.

The following is a link to all the research I’ve found regarding the clearcuts don’t burn phenomenon.

If anyone would like to see more photos of the phenomenon, here are two links- they are posted in Google documents. Clearcuts don’t burn I and Clearcuts don’t burn II.

4 thoughts on “Impacts of Fire Disturbance on Anthropogenically- Induced Vegetation Mosaics”

  1. I wonder, when humans were around but didn’t control fires, whether our interior forests looked more like Derek’s first photo. I wonder whether the fire and forest ecologists who study the past could tell us that.

    That makes me wonder if the past forests look like that, when people study the past and tell us large acreages of beetle kill didn’t make fires worse (or increase fire risk or hazard, or however they framed it), it was partially because it was more of a mosaic.

  2. So, if I send in photos showing charred clearcuts next to green or hardly burned native forest or old-growth that will then mean beyond a doubt that…?

    • Matthew

      You are welcome to reinvent the wheel if you don’t trust foresters training and experience. It is all about probabilities and you would eventually come to the conclusion that there is no one size fits all solution nor is there any guarantee that what should have worked will work. However, if you follow sound forestry practices, you will win more than you loose and you will definitely be better off than if you had taken a let nature take its course approach.

  3. I’d like to see those photos Mathew. Perhaps you can give me the Lat. and Long. of these sites on Google Earth and I can go visit them? I have no doubt such sites exist. I once saw a USFS aerial photo of an “underburned”(green) old growth patch next to a burned clearcut. Perhaps it was slash. I always wondered why the “Jocko fire” burned so much Plum creek land. Then I got a clue when the USFS mentioned they(PC) had “pre-commercial” thinned (pulp) 7000 acres in the last 10 years. The unthinned patches of “regen clearcut” lodgepole were green islands in a sea of burned shelterwood mixed conifer. Someday maybe a Plum Creek forester will fill me in.

    I’ve always said that 20-30% of clearcuts burn for the various reasons I’ve outlined in the link above. But, when I think back to those burned sites, I cannot think of one burned clearcut that was adjacent to an unburned stand of old growth(or mature). Not on the Montana fires I visited at least. It does amaze me how isolated Larch can survive an inferno. Otherwise, I’ll let the pictures speak for themselves.

    And who am I to say. These are just the observations of an arthritic old land surveyor. Perhaps you’ll join me in calling for academia to research this. With all the google earth, AUTOCAD and GIS technology out there, it shouldn’t be hard for a geography or forestry student to map burned and unburned clearcuts and old growth and compare their ratios.It’s not to difficult to overlay a burn severity map on top of a “past treatments” map or pre-fire structure map. That was my epiphany.

    This subject is just crying out for a bright young grad student. With all the proposals poppin up in the West to salvage log and fire mitigate MPB this is going to be a hot subject for several years to come. This is the kind of research that’s gonna make you stand out in the pack of dissertations. And it might actually have some real world implications.


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