Wildfires in Clearcuts

[BuzzH]

cjcj, since you asked Rockydog about fires in clearcuts and how they can burn more...I'll take a stab at it.

Really this does depend on the type of clearcut and whether or not its been broadcast burned or not. That said, most cutting units are not burned for at least a couple years to allow the slash to dry so a broadcast burn can be effective on reducing the fuel load. Of course some units arent burned for several years, for all kinds of reasons...mostly air quality and burn window issues.

This is a photo I took while I was fighting a fire in 1994 in Montana, near the end of August. This fire started by lightning, on the edge of a clearcut and when we arrived was about 2-3 acres. By the time we'd walked down to the fire, about 1/4 mile, it had quickly grown to about 10-12 acres with flame lengths 40-50 feet. I determined it was burning too intensly for hand crews, pulled my crew to the road, and ordered a few loads of mud to cool the bastard down a bit. If I remember right, we got 6 loads of mud on the thing before we could begin hand line. In that time frame of about an hour the fire had ripped through the 50 acre clearcut and slopped over the upper road into the timber. Once the fire hit the timber, it layed down and moved one hell of a lot slower through the understory and never did reach the crowns. The flame lengths were 2-5 feet in the understory of the timbered part. The reason for this was because of the fuel loading in the clearcut, combined with the fact that everything is exposed to the sun, drying the fuels more and faster in the clearcut. The fire in the timber simply crept through the understory as there wasnt hardly any available fuel and I'd guess fuel moisture content was a bit higher.

Now I know theres a jillion different scenerios, but its a goddamned falicy that fires wont burn through clearcuts, and in some cases, like the one mentioned above, they actually burn more intensly in them.

Another shot of the same plane coming in.

 

[Ithaca 37]

cjcj, Here's what I've observed. The clearcuts have a lot of brush and grasses in them for at least the first 5-10 years. They dry out in the hot summer sun and ignite much more easily and burn hotter. In Idaho the fires often jump from clearcut to clearcut as the wind carries some light burning embers sometimes as much as a mile and they set another clearcut on fire. As for human caused fires, the logging roads to the clearcuts provide more access for vehicles and more chance of a fire being set accidentally.

"Of course clearcuts burn. When long, hot summers dry out the grasses, brush, and logging wastes, they can flare explosively. When they grow thick with closely packed young trees, they present exactly the fire danger we are wrestling with now. The logging roads provide human access that is the source of the vast majority of forest fires. (from Dr. Thomas Power, University of Montana, August 15, 2000)


Two good examples of how fires seek clearcuts and logging roads, and ignore the moister old growth: the Raft River Fire on the Olympic Peninsula, and the Sundance Fire, in North Idaho--both in 1967. In the former, the fire literally raced from clearcut to clearcut down the logging road, completely skipping the old growth in between. In the latter (70,000 acres), the burned area was entirely in an area laced with logging roads and logging scars, once again largely ignoring the uncut areas."

http://www.wildrockiesalliance.org/issues/wildfire/15facts.html

""Over and over again the media portrays fires as some kind of catastrophic disaster," said Wuerthner. "Yet wildfires are to western ecosystems what rain is to a tropical rainforest. They are necessary for the continued health and existence of these ecosystem."

"Wildfires cleanse the forest of disease and insects," he continued. "They thin forest stands. They recycle nutrients. They create snags that are homes for thousands of species. When such snags fall into streams, they provide bank stability and fish habitat. We couldn't pay enough or hire enough people to all these positive things in our forests that fires are doing for free.""

http://www.monitor.net/monitor/0008a/1forestfire2000.html

<FONT COLOR="#800080" SIZE="1">[ 06-06-2003 18:17: Message edited by: Ithaca 37 ]</font>

 

[cjcj]

thank`s for the education, i don`t think i`ve ever said clearcut`s don`t burn, and the link rockdog posted mostly shows devastation in dollars [homes etc.] but as was stated all fires are not the same ,had that dry fuel from those clearcut`s been gathered and burned, then you wouldn`t have that hot fire mentioned, in fact after seeing the devastation of that az fires,caused last year you could see some place`s where the fire burned just the top`s of the tree`s,and that was strange looking,and in one subdivision one cabin would burn, but miss the next one, it was like the fire played hopscotch over the whole area, i`m not about to challenge your info, i think it`s correct, but i also don`t think you can predict the nature of most forest fires. but thank`s for the education, i`m alway`s willing to learn.

 

[cjcj]

oh yea cool pictures!

 

[RockyDog]

Thanks Buzzh and Ithaca. You have alot more perseverance than me. But it still seems as if your posts did not sink in.

<FONT COLOR="#800080" SIZE="1">[ 06-10-2003 09:18: Message edited by: RockyDog ]</font>

 

[cjcj]

they sink in rock boy, it`s just that you can`t explain yourself! and you know that the fact is no two fires are the same , but ONE fact is clear, FIRE doesn`t burn without FUEL! and this INCLUDES LOG`S!

 

[ELKCHSR]

There have been exhaustive study's done on fuel loading and types, I have quite a few different manuals and hand outs on this very subject, from how much projected fuel is on the ground and standing in tons per acre, how tall, size and type of vegetation, moisture content on types of fuels, terrain, aspect, time of day-month, elevation, relative humidity, wind speed, the list keeps going, so one that studies this stuff intensely will get a really good handle on the basic behavior of most all fires...
There has been a very good and solid science done to evaluate this stuff, now there are things as with all things in nature where it doesn’t always follow the steadfast rules of what has been written down, so there is always the chance of things not going according to Hoyle, look at what is going on in Arizona right now, they sure didn’t seem to notice the signs of the sixty mile an hour winds coming thru when they did.