All About Clearcutting
Everyone should be outraged at the ugly scars on formerly green mountainsides left by clearcutting, the practice of removing not just the trees needed for logging, but everything else as well, leaving only bare dirt. But many of us are not completely aware of the reasons this is done. Today we let forestry science answer the question of whether clearcutting truly does reduce the amount of old growth forest, or if it might (counterintuitively) leave us with more.
Today we're going to dig into an emotionally charged issue, the clearcutting method of logging, which leaves the forest stripped clean of trees and everything else. It raises anger among anti-logging activists who want the forests left natural, and that causes conflict with the loggers who note the activists still expect to fill their lives with wood and paper products. Some believe clearcutting is merely a lazy and destructive tool of the greedy who couldn't care less what the forests look like, or whether it can ever recover, so long as they can extract every last penny from it. Today we're going to find out whether clearcutting is truly as destructive as the activists think, or whether it's as necessary as the loggers say, or whether there's a bit of truth on both sides. Because whatever your position, it's to everyone's advantage for that position to be better informed by the best data we have.
First of all, let's make an important distinction. Clearcutting and deforestation are two different things. Deforestation is the permanent removal of forest to make way for cattle, agricultural, or other repurposing of the land; clearcutting is a logging method where the forest grows back. That's what we're talking about today.
Obviously, clearcutting is ugly. It leaves great patches of bare ground where a forest once stood. These patches can be as small as five acres, and in the largest can be several hundred acres. They are usually seen interspersed with stands of trees that may have been clearcut previously and now have juvenile trees, or may be uncut old growth. But the near-universal reaction to clearcut patches is that they're ugly. So how did we get here?
In the 18th and 19th centuries, logging was done when there was little understanding of forestry or ecology, and nobody ever gave a thought to running out of forest. Then in the 20th century, land was getting purchased and loggers had to start thinking about efficiency. What arose was a practice called high grading. Loggers would select all the best trees — those that were biggest and straightest and of the right species to meet market demand — and ignore the trees that nobody wanted. This improved their efficiency and profitability, but it left forests in a pretty bad condition. Trees didn't seem to want to grow back.
Eventually, logging companies started to get deep into forest science. The best way to create long-term profitability is to log in such a manner that the forest will return as quickly as possible, so in at least that one sense, logging industry and activists are on the same page. This is what led to the development of silviculture, the science of regrowing forests. Clearcutting — where everything is taken from the land, including bad and damaged trees, trees of an undesired species, even shrubs — is not just a logging method, it's also one of the most-practiced silviculture methods. If it was just about removing trees, also taking the stuff you don't want just costs extra money. Logging companies wouldn't do that if it wasn't an effective silviculture method. And they need to be in business tomorrow and next year, so silviculture is absolutely worth every penny of investment. So why do they spend the extra money to clearcut everything?
The basic reason clearcutting works as silviculture is that by replanting saplings into an environment with no competing trees, it was found that they grew back fastest and healthiest. Trees also use a lot of water, and where other trees have been removed, more water is available for the saplings. They also get full sun.
A clearcut area can be the best possible environment for new trees to grow — can be, but not always. Trees come in many different species with many different needs, they have different methods of seeding, and they grow in different ecosystems with different conditions. Different types of silviculture are practiced in different forests. In some cases, a variation called seed tree is used, where some of the best trees with superior genetic traits are left standing, sparsely throughout the nearly clearcut area, to reseed the area naturally; and then once the new growth is established the seed trees are removed. Another variation is called shelterwood which leaves more of the original growth standing, best in cases where growth of the desired species will thrive under partial sun and undesired species wanting more light can be minimized by the shading. In all three methods, you eventually end up with a stand of trees of all the same age and species, and in optimal health.
All of these methods — along with others and including all sorts of variations — are better than high grading, where loggers used to go through and take just the trees they wanted. Saplings don't thrive where there are too many other trees still around because there is too much competition; they don't get nearly as much water and light as they would in a clearcut area. High grading also leaves the forest unsuitable for future reharvesting, because every time you high grade through a forest you leave it with a higher percentage of undesirable trees, and only minimal slow regrowth of desired trees. And if you can't reharvest here, it means you have to go find a new place. This is the basic reason loggers don't leave as many trees as people would like to see.
A common characterization of clearcutting that's often given in its defense is that it mimics a forest fire. It's common knowledge that fires, while destructive, are necessary to the long-term life cycle of any forest system. The undergrowth is cleared out, old deadwood is removed, the ability for light to reach the forest floor is restored, and some types of flora actually require fires to reproduce. It's a periodic reset button that gives the forest a fresh, clean restart. And the comparison actually holds up quite well, but only to a point. Clearcutting does provide all the benefits just listed; however, it's far from a perfect emulation. The greatest difference between a burned forest and a clearcut forest is found in an unexpected place: the water chemistry of its streams. These differences are diverse but consequences are relatively minor, except for one: sedimentation. Both clearcutting and fires will result in increased sedimentation because there's no longer any undergrowth holding some of the soil to the hillsides. However, the biggest single driver of the increased sedimentation following clearcutting is also from an unexpected source: it's not the cutting itself, it's the dusty dirt roads created and used by the loggers. This increased sedimentation has unambiguous detrimental effects on the stream biota, especially during the summer. Research has found that logging companies should maintain higher quality roads that don't degrade so much, and should minimize their placement near stream headwaters.
Trees are not the only citizens of the forest. Wildlife of all kinds also calls the forest its home, and impacts to wildlife are another of the most visible areas of concern with clearcutting. Obviously, wildlife numbers are directly related to habitat size and availability. A lot of research has been done on this over a long time, but perhaps the largest single project that has produced the most and the best data has been the Northwest Forest Plan (NWFP) enacted in 1994, covering 100,000 square kilometers of federal forestlands in the US Pacific Northwest. Ten federal agencies are involved in this wide-reaching plan with a stated mission of being "scientifically sound, ecologically credible, and legally responsible." Among many other things, it halted all clearcutting of old-growth forest on this land, and included strategies to protect many particular wildlife species.
In 2015, the NWFP scientists drafted their 20-year report — and pretty much everyone was surprised at everything in it. Much of what scientists expected to happen turned out to be wrong. Bird populations continued to decline, exactly the opposite of what was expected. Loss of old growth acreage increased, also in contrast to expectations. The reason? Fires. Forest fires were larger and more destructive than ever before, and this trend is projected to continue far into the future. In areas where clearcutting was continuing, losses to the increased fire activity were lower than expected. One reason appears to be that clearcut areas act as a sort of fire break, keeping the wildfires in those regions smaller and easier to contain. The somewhat-counterintuitive bottom line is that the combination of clearcutting and forest fires — according to the data so far — leaves us with more total acres of forest remaining than do forest fires alone without clearcutting, and corresponding greater numbers of wildlife populations and species diversity.
I'd like to close with a small personal anecdote from my research on this topic (which I don't do often, so humor me). I found one news article in which the reporter pointed to a freshly clearcut hillside, and asked the logging exec "You think that looks aesthetically pleasing?"
And he answered "I do. Maybe I'm somewhat biased, but when I look out, I see sustainability and rejuvenation." Now, if you're like me, that probably made you roll your eyes and laugh at the transparent spin doctoring. It's an ugly, blank hillside covered in stumps and scars. I live in Oregon, and every time I fly I look out the window and am sickened by the tracts of clearcut mountainsides. But also, where I live, I often drive through areas recently razed by horrific, Biblical-scale forest fires (I'm something of an anachronism, driving my Tesla through logging country). Some of these burn areas are a few years old and the hillsides are absolutely thick with brilliant bright green young saplings, all the same age. I've also stood in a tract of clearcut former forestland, and — once you're there and not viewing it from airliner altitude — you see the exact same explosion of life. Mr. Skeptoid is (unsurprisingly) not one to anthropomorphize trees, but it's hard not to be happy when standing amid countless thousands of waist-high saplings. I do think that there is a middle ground where the logging industry and the anti-clearcut activists can meet. Perhaps both sides could improve the quality of their communication. Perhaps both sides could take a step or two toward understanding the other's perspective.
Taking everything into account, the best-supported conclusion on the question of clearcutting is that it's very ugly, at least macroscopically; but nature can be plenty ugly on her own as well. And ugliness is only in the eye of the beholder. Clearcutting is incrementally more damaging to the environment than nature's worst will always continue to do, but unless we're all willing to give up having wood and paper products, it is more or less in balance with that need. Forestry scientists are awesome and do amazing work, and their valuable skills will continue to inform and improve forestry management practices.
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