Let’s look some more at thinning.
First, I’ll say that I don’t know about wet areas. I remember a class at an Area 4 Silviculture Workshop in the 80’s, taught by Chad Oliver and Bruce Larsen (then of U of Washington). All the models were based on competition for light. I asked “but what if the trees are competing for water?”. That wasn’t part of modeling at the time. So much of forest ideas and models were generated from wet forests and don’t apply to dry forests. The point being that any discussion of thinning needs to be grounded in specifics of when, where and why.
At one end we have “no thinning is ever ecologically necessary.” Well, that’s a high bar, and not one that’s in law anywhere as I know for activities on National Forests. I don’t know that campgrounds or ski areas are ecologically necessary either. So the term “ecologically necessary” has to carry quite a bit of weight, especially if different fuels-related assumptions are involved. Are fuels prescriptions ecological? What if the fuels practitioner is trained as a fire ecologist? What do we mean by the term “ecological” in that sense?
Anyway, I’ll make a series of claims that we can discuss.
1. Thinning in forests is very common, at least here in Colorado, outside of a wood products context – purely for fuel treatment or wildfire mitigation. Then there are the folks in Arizona and the Lake Tahoe area, trying to find and encourage wood products companies to take their thinned material.
2. Some people thin in dry areas to reduce density of trees, because more trees can get started than the site can ultimately support. Thinning gives the remaining trees a better chance to get enough water to grow.
3. Some people thin (at least in California) to return to HRV (with the side benefits of fewer stems on health and resilience as above.)
4. Healthier trees (with stem reduction) are often, but not always, more resistant to bark beetles.
5. Removing biomass (cutting trees and removing them from the site by burning or other removal) reduces fuels.
6. Thinning can be done to help trees grow larger faster, as with west side plantations trying to get bigger trees for habitat, or in many places for wood products.
7. Some species, in some situations, have a tendency to stagnate rather than develop into stands such that without thinning trees don’t become large (“doghair”)..
To engage with previous comments:
Jon said:
It looks like this was looking at basal area rather than the size of trees removed, so I don’t think it proves the point that removing large trees is necessary to protect large trees from drought (or fires?) – unless large trees are all that were growing here.
Yes, I would say if all trees are large in a stand are large, and you want to thin, you would need to remove some large trees.
Jon also said in an earlier comment:
we should minimize it and be choosy about where that is done. Not to mention clearly explaining all this in the rationale for a project. This is what I’m not seeing discussed.
As we shall see in the next post, at least some environmental documents do have rationales and different ways of monitoring “choosiness” have been proposed.
Jake had some interesting comments:
While mortality from MPB was significantly less in the thinned areas (3% vs 13%), when the trees killed by the thinning (which also removed infested living trees) were included in mortality, total mortality is much greater in the thinned areas.
Let’s think about this some more.. (I didn’t go back and look at the study). When the thinning occurred, they removed more trees than might have been killed by beetles. But the way the stand develops, with more standing and falling dead trees (with MPB death) would be different, and more fuel would be in the stand. I’m not sure that those prescriptions were intended to reduce fuel loadings at the time, but I think it would be hard to argue that such a prescription would not reduce fuel loads.
Is that really “shady accounting” as Jake states? If the goal is to reduce MPB kill, then thinning would generally be successful. That would be in the framing of the study itself (reduce MPB mortality) rather than (how to maximize living trees on a site).
Also, the Negron et al (2017) study reported that 4 of their 21 thinned stands had much greater MPB mortality than the paired unthinned stands
That’s the “it doesn’t always work” argument. We’ve discussed that before with regards to fuel treatments in general.
Another of Jake’s comments:
Thinning, of course, had the benefit of providing saw logs to the mill, but it also probably came with significant costs to the ecosystem.
“Costs to the ecosystem” “ecologically necessary”. I thought the “ecological integrity” part of the 2012 Planning Rule suggested managing for NRV- related to HRV. But not if HRV is too open or requires thinning. It’s all very confusing.
Instead of “ecological integrity” perhaps the FS should have targeted “forest resilience” which would definitely have a fuels (both for the trees on-site and to support suppression via PODs and other fuelbreaks.
But what “costs to the ecosystem” come from thinning specifically? Wouldn’t it depend on when, where and why?
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A quick question:
If there is a stand of only large trees, is it really at-risk to high-intensity fire (if not ‘thinned’)?
That is my question – “if all trees … in a stand are large, and you want to thin, you would need to remove some large trees” – but why would you want to thin? And why wouldn’t it be more important to thin somewhere else, and is it more important to thin large trees than to leave them because there is a shortage of large trees (compared to HRV or NRV/future)?
Jon, check out the Tahoe write up in the next post. It seems like that would answer your questions.
Chances are, such a stand already has wildlife protections, sometimes even if there is no documented usage. If one Owl PAC burns, another similar stand can be a replacement.
My personal observation of east side Oregon pine forests is thinning for the short term gain is a fool’s errand. Thinned or untwined, fire mortality is the same: Almost complete.
Thinned will have more green needles albeit separated crowns. Untwined is canopy closure and tassel tops. Fire mortality also almost complete.
In the original stands, mature, and prior selective logging, the trees shorter than my arbitrary feet were all lost, and where ladder fuels were present there was loss of mature trees of my estimated 20″40″ DBH and total tree heights of 80-120 feet on steeper aspects and a tad shorter on level land. Wind driven fire. had to be 30 ft or higher flame heights.
My conclusion, that of an old man with primary work in temperate coastal forests where wind stunts trees where annual precipitation 60-120″, is that most thinning in western pine forests does not take enough trees. My thought is you carefully examine to determine the best tree to leave and only 25-30 per acre. Entry down the road is to either cut and pile to burn in winter, or broadcast burn the ingrowth in spring d before it becomes too much and too dry. Leave any replacement new trees since thinning where a leave tree has died. The driving outcome is a forest and one that can survive frequent low level fire. One where fire can be fought and suppressed with minimum tree and stand losses.
A side note is that private insurance is essentially not economically possible for timber on private land. Thus, husbandry has to be economically possible when replacing lost forests. Unsalvaged burned timber is the run up to a reburn. Emigrant fire in 2025 on the Willamette burned the Tumblebug fire scar from 2009 fire with no meaningful salvage logging. With no remediation, there will be fuels enough on ground steep enough, to have another fire in the still unburned fuels and regrowth fines. Each exposes the diminished soils to high level erosion. I have not been there yet. Middle Fork RD had placed logged. green timber into the Middle Fork Willamette to create “natural” logs for cover to provide sanctuary for “bull trout,” the ESA listed S. Malmo renamed S. Confluentus due to loss of access to an “at sea” anadromous journey and most of that due to geotechnical uplifting and waterfall barriers, as has happened with O. Clarkii to become C. Lahotan trout in the Great Basin, West Slope cutthroat in the Rockies, and Rio Grande cutthroat. O. mykiss the hot water tolerant interior and landlocked Redband Rainbow trout.
I have read no science that declares conflagration fires and rev burns are benign events for soil disturbance and enhanced storm water runoff and logging is ruination for the same. All of which brings to life how cutting green trees to place in a stream to create habitat that fires certainly will increase and augment. Dead trees become snags, and snags rot and fall to their heavy side, which is towards the light of the opening over a stream, to become drift to pile up on inside corners or force into the banks and upwards on outside stream corners. Would not the logging, the hauling by log truck to where a tracked log loader can remove the logs in the riparian area (verboten in logging) to place the logs in streams that most of my logging and timber purchaser experience was any log in the creek, all year or seasonal, had to be removed. 1993 and logging came to a standstill on federal timberlands, and then contracts were let in both State and Federal land ownerships to have NMFS and NOAA, EPA directed placement of LARGE diameter logs into streams. Coals to Newcastle. Do as we say, not as we do. Sovereign immunity.
Why not let a contract to fall trees into streams as part of rehabilitation of the fire scar? Before they burn as fuel for the soon to come reburn; while the wood is still sound which obviously was why dead blow down along roads was not used in bull trout habitat improvement.
Where is the POD cut merch to be disposed of? If PODs are paramount to fire control and area burned reduced, why are there not ongoing full blast emergency POD creating contracts being let? After all, a POD is “accepted resource loss” prescription management for fire suppression. Is there a comprehensive timber salvage and road construction plan for post fire in a POD? Chief Moore suggested an end run around NEPA with “using unplanned ignition as opportunities to reduce forest fuels.” Is not the same available to do the same with what happens to the timber killed in fire within the POD boundary? Reasoning: To reduce the fuels for a reburn. Just a part of the plan to reduce fuels to reduce fire losses to resources, understanding that most returns do consume more green timber at the fringes of the burn scar.
Why my concern? Thinning works ONLY if you remove the fuels from the cutting of trees and brush. Logging or controlled burns. Why would a POD not also be better for the future and potential returns with the dead timber removed? “An opportunity to reduce fuels due to having a plan for outcomes of using PODs to suppress and control wildfires.”
Thinning creates its own set of issues …
1. More light on forest floor = more ground cover, which dries quickly in late summer = kindling.
2. Wind becomes much more of a factor with a wildfire in thinned forests.
3. Surface heating increases; evaporation increases. Leading to global warming.
4. Removal of biomass removes stored carbon that is either burned or processed.
5. Fossil fuel energy used during thinning projects.
6. Poorly understood – and highly variable – impacts on wildlife, insects, soil microbiome.
Thank you.
Those are talking points, Glenn.
The rest of us are sharing our own observations and photos (see the one at the top of the post) of specific places.
Here’s a 2026 review paper comparing ecological costs and benefits of thinning:
https://www.sciencedirect.com/science/article/abs/pii/S000632072600056X
You’ll only get an abstract and snippets from this link, but I think the whole paper is worth reading.
Jake I looked at that piece and it’s a perspective (not a paper, a science op-ed) and the authors include Hanson and DellaSalla and Law, so I think I know what to expect. Nevertheless, since scientists don’t really do back and forth (there’s no institution that I know of to promote it) I’m ready to take a look. I will see if I can get an e-reprint from the lead author.
Also it looks like it was published in April 2026 (?).
It’s a review of previously published scientific papers, not an op-ed. I can send you a copy if you give me an address. I know you disagree with Hanson’s, Dellasalla’s, and Law’s results, but they are scientists and their work is published in peer-reviewed journals just like everyone else’s (except, perhaps, the USFS internally published studies).
Yes, well my observations suggest that perspectives are often quite like op-eds only they have citations, that’s why I call them “science op-eds”. .. you can email me at sharon at forestpolicypub.com.
To me, it just makes sense to thin! But how to thin? If you are in the South, you will thin early and often – usually. There is a 120 acre plantation next to some older timber stands (we own the older stands, the plantation is industrial) that was planted in 2000. Beautiful improved loblolly, probably 200 sq ft/acre, average 14” diameter. The owners (Potlatch/Deltic) are going to clearcut 26 year old lob! That’s where their $ is.
Same company, similar plantation and they thinned from 200 to about 100 BA. Weyerhaeuser back here thins and fertilizes, with three thinnings per 50 year rotation. Priorities, I reckon. USFS here pre-commercial thins and begins commercial thinning at about 25 years. I’ve seen 16” average dbh in 25 year old Lob! Most of these FS areas are 100-120 year rotation.
Back in Oregon, we thinned, I believe it was programmed to three entries, with the final being a shelterwood prep cut. Not many yellow bellies were thinned due to age but we did do some shelterwood in dry-site pines. I had a large thinning project around the Big Summit Prairie, in a fine stand of second growth PP, that we carried high BA to maintain 60% crown closure. Turned put well but was really difficult to maintain quality of crown closure. Read: took a long time to mark! 🤣
AZ and NM used the term “thin” but it wasn’t really what I would call thinning. It removed, as I’ve mentioned before, down to probably 20 sq ft/acre. NOT 4- FRI, but White Mountain Stewardship. The A-S had lost over a million acres to wildfire in a 10-year period, and even CBD realized something has got to change. 4-FRI uses a clumpy/groupy (spotted dog/hog) approach (GTR-310) to develop “fire safe” zones for generating openings, and keeping seedlings/saplings alive during wildfire. Goshawks are a big driver in 4-FRI. Richard Reynolds has a paper on this.
As for MSO, by the time I left Arizona, the USFWS determined 70% of MSO population had been lost to wildfires! It has only gotten worse since the, making is questionable whether a “taking” due to treatment disturbances is really a thing anymore…..
I thinned lodgepole on the BLM on Colorado and it turned out well. It was WUI and probably removed a third of a well developed stand, averaging 9-10” dbh. With all the beetle kill around, but not close, absolutely no bark beetle issues. Dave and I have talked about this at length – I have no clue why/why not the bugs have left Lake County lodgepole alone…..
Thanks for the roundup of thinning around the country, Jim!
Yeah Sharon, as a forester schooled in silviculture – both educational and job performance, anyone would know the value of managing crop trees! Most folks of the preservation persuasion will be against any form of mechanical, or fire stand manipulations to stimulate growth. I was hired to grow trees first; planting, silviculture prescriptions, appraisals, mark and cruise and administration of timber sale contracts.
Leadership comes later, when you put all other disciplines on that plank of performing for the American people. I didn’t mention Planning specifically, but my first EA’s were on the Ochoco in the late 1970’s. Fast as I could run, I could never outrun NEPA…..🤣
“Costs to the ecosystem”? I can’t think of any.
Seriously, I can’t think of a single cost, if you take a whole-ecosystem perspective and long-term view, and if project goals are ecosystem restoration. There may be short-term impacts, but in the long term the benefits greatly outweigh the short-term negatives in basically all cases
Of course it does, T! 👍
If project goals are ecosystem restoration (and we all agree with what that is based on science and the forest plan), the exception would be where the short-term negatives exceed some substantive threshhold that would delay or prevent recovery, especially in a threatened/endangered species context.
Sharon wrote about thinning projects designed to mortality from fire, insects, and disease that resulted in less living trees than unthinned areas:
“Is that really “shady accounting” as Jake states? If the goal is to reduce MPB kill, then thinning would generally be successful. That would be in the framing of the study itself (reduce MPB mortality) rather than (how to maximize living trees on a site).”
This suggests to me that only chain-saw mortality is acceptable. Mortality due to fire, insects, and disease are not. It sounds like a silviculture view, but not a forest ecology view.
Also, in the Negron et al 2017 study, sure, the unthinned stands would have “more standing and falling dead trees (with MPB death) would be different, and more fuel would be in the stand”. Several studies have shown that beetle-killed forests do NOT burn at higher severity or higher frequency. And the unthinned areas would also have more carbon storage, more snags, more coarse woody debris, and less soil disturbance that usually leads to invasive weeds.
Finally, in your series of photos at the top, I like the 2010 pre-treatment ecosystem. How do you know that there would have been overstory mortality if it hadn’t been treated?
Yes, If perhaps 80% of trees (by tree count) are thinned from one plot, and an adjacent plot is not thinned, and then bark beetle comes through, both the percent and absolute number of trees killed by bark beetle in the not-thinned plot may be greater — yet a greater number of living trees will likely remain on the not-thinned plot because so many trees would have been killed by cutting on the thinned plot. So it really is “shady accounting.” BTW, in the SFNF we have seen prescriptions for more than 90% of standing trees to be cut, although I think they may have lightened up a bit on the percent cut in recent years.
Sharon’s question: “But what “costs to the ecosystem” come from thinning specifically? Wouldn’t it depend on when, where and why?” Yes, it would. Generally, the costs become greater when forests are drier, such as in the dry forests of the Southwest. The SFNF can be considered the “canary in the coal mine” of ecosystem costs from thinning https://www.counterpunch.org/2024/02/09/thin-from-below-in-dry-forests-out-of-the-frying-pan-into-the-fire/
I don’t think I would use the SFNF for any “canary” other than what NOT to do in fire and fuels management…..
Just saying……
I see your point, but it’s also possible that they are trying to apply methodologies to the very dry SFNF that work better in wetter forests. There are clearly elements of human error in the multiple prescribed fires turned wildfires that have occurred on the SFNF, but I think the bigger picture is that the types of fuels treatments that may work to some extent in wetter forests simply do not work well and safely enough in dry forests like the SFNF. I believe there needs to be a very different strategy applied to these dry forests. If cutting and burning is to be carried out, it needs to be limited and strategic because there aren’t enough safe weather windows for extensive burning, and the vegetation is often very dry. Any cutting requires burning in order to consume piles, and also to burn off the shrubs and weeds that grow in the opened-up and dried out areas that formerly had much more tree canopy cover. All of this is risky in dry forests. One of the lessons learned in the Calf Canyon fire review, the “Gallinas Canyon Pile Prescribed Burn 2022 Declared Wildfire Review,” was that:
“Execution of the mechanical thinning prescription resulted in an open canopy that increased the amount of solar radiation and in-turn increased the rate of snowpack sublimation and snowmelt. In addition, the open canopy may have increased post-thinning windthrow that increased surface fuel loading significantly between thinning and pile burning treatments.”
https://lessonslearned-prod-media-bucket.s3.us-gov-west-1.amazonaws.com/s3fs-public/2024-06/Gallinas%20Canyon%20Pile%20Rx%20Burn_2022.pdf
I have long been advocating for a “from the roots up” reassessment of fire and forest management strategies for forests like the SFNF. Clearly the current strategies are not working well.