We have had some discussions of thinnings and how material can be left, and may dry out, and thereby make fires hotter potentially closer to the ground than they would otherwise be, in thinned stands. One of our readers (thank you!) sent us these photos. You can click on these to get higher resolution.
what is the four mile report that described how thinning can makes fires worse?
I have little doubt that without adequate slash treatment they surely can increase severity but there have been other studies describing reductions in fire mortality after fuels treatments and thinning, under the right conditions.
Contrary to clear evidence, some contended for years that thinning makes things worse, with blatant miscitations of some studies. Too typical. But I always wondered, so contrary reports of negative impacts from a reputable source are quite welcome.
Sorry, I have a bad habit of writing my posts and editing them right after I post them. Originally in the post I did refer to the 4 Mile report and then deleted it, because I couldn’t find the comment I wanted to refer to..
But then after you commented I applied myself with greater energy and did find it…
http://ncfp.wordpress.com/2012/08/30/report-prior-fuel-treatments-ineffective-at-moderating-fourmile-canyon-fire/#comment-10284
And you can check out the rest of the discussion and the report. What is interesting about the report is that it seems to have been applied generically in various statements by folks since.
OK,I skimmed the 4 mile report and it seems obvious that a lack of slash treatment and scattered treatment areas failed to dampen the fire. It is also obvious that under the right conditions, things can burn hot no matter what the treatment or how widely spaced the trees. The treated areas above Alpine in the Wallow fire did dampen the blaze enough to protect homes but did little to reduce mortality given the weather conditions.
We need a chart describing the performance of these treatments in different fires under different landscape and weather conditions. It has been a few years since i reviewed the lit myself.
But i can’;t imagine the areas in the pics above not being effective under most conditions. These are not areas which will see a lot of shrub growth in the understory although the need for followup treatments in 10-20 years is likely.
I agree with the comment by Bob Zybach in the 4 mile discussion, some treatments look silly.
It is about 9 am here in Gonder, northern Ethiopia, Simien mountains.
This is “whole tree harvesting” in action. Limbs and tops are skidded to the landing to be processed by a boom delimber.
The top photo is one day after cutting. The middle photo is one week after thinning. No slash. No need to RX burn.
Both photos are around a 25′ spacing, 50 Basal Area, crown fire hazard eliminated.
Mechanical logging is cheaper, safer, and better for fire hazard. One of the big reasons for starting WTH 25 years ago was the steep increase in Workmans Comp for cutters. THe other reason was smaller diameter trees to harvest. In 20 years, these trees will be 16″ DBH (currently 12-14″). The thinning release will be dramatic. On the top photo, 90% of the trees harvested were 12″ an under.
In P pine stands in central Oregon, such whole tree harvest appears to be the norm. On such gentle terrain it seems appropriate, not much ambiguity there and from what I understand soil impacts with new equipment is minimal. Burning such gentle terrain usually laced with way too many roads is also easy.
Many would agree with this but the problem is that many steeper mixed conifer stands look little like this.
We keep coming back to P pine, but we need to look at the other more difficult sites where cable logging is necessary and large amounts of slash need to be treated. Setting slopes on fire invites a host of problems, it is not easy as this.
I have thinning photos from a number of other places that raise more difficult questions.
Greg, does cable logging use WTH today? Do they delimb the trees on the landing? An old forester told me they used to “broadcast” burn the old skyline units in the 80’s, do they still do that? I’m just curious. I suppose it depends on the size of the trees. Didn’t mixed conifer evolve with a infrequent stand replacing fire regime? Or at the least a mixed severity. Doesn’t a variable retention “regeneration” harvest serve this purpose? Of course, if you want to retain scenic values..that’s a different question. Slope is a tough problem for fires. When I photographed the “green islands” of the regen clearcuts that didn’t burn…the one place they did burn was steep slopes.
some cable logging used WTH but i have not seen too much of it.
More often slash is left to be burned, usually piled and when they set it on fire, there can be damage to residual trees, sometimes a lot, sometimes none at all. It depends on how much is left.
Yes, they used to broadcast burn old skyline units, I planted many like that, we called it “gravy” with such a clean burn but that is in the past.. Without such burns it could be really hard to get the trees in.
Lots of mixed conifer. p pine dominated stands have “encroachment” by fir in understory, such as also seen in sequoias.
Higher elevation mixed conifers more often have stand replacement regime,although quite variable.