Seeing the Forest for the Trees

There’s an old cliché that one can’t see the forest for the trees. It is used to describe people who are so focused on some detail that they fail to see the big picture. Nowhere is this failure to see the forest for the trees more evident than the rush to utilize dead trees for biomass fuel s and/or the presumed need to “thin” forests to reduce so called “dangers” and/or “damage” from wildfire and beetle outbreaks.

Contrary to popular opinion, we probably do not have enough dead trees in our forest ecosystems. And this deficit is a serious problem since dead trees are critical to the long term productivity of forests, and perhaps more important to forest ecosystems than live trees. Dead trees are not a “wasted” resource. It is questionable whether we can we remove substantial quantities of live or dead wood from the forest without serious long term biological impoverishment to forest ecosystems.

An abundance of dead trees, rather than a sign of forest sickness as commonly portrayed, demonstrates that the forest ecosystem is functioning perfectly well. For far too long we have viewed the major agents responsible for creation of substantial qualities of dead trees--beetles and wildfire—as “enemies” of the forest, when in truth; they are the major processes that maintain healthy forest ecosystems.

Recent research points out the multiple ways that dead trees and down wood are critical to the forest. One estimates suggests that 2/3 of all species depend on dead trees/down wood at some point in their lives.

Dead trees are very important for functioning aquatic ecosystems as well. Trees create structure in streams that shapes stream channels, reduces water velocity and erosion, and provides both food and habitat for many aquatic invertebrates. In general the more wood you have in the stream, the more fish, insects, and other aquatic life. Aquatic ecologists generally believe that there is no upper limit for dead wood in streams.

Once a tree falls to the ground and gradually molders back into the soil, it provides home to many small insects and invertebrates that are the lifeblood of the forest, that help recycle and produce nutrients important for present and future forest growth. For instance, there are hundreds of species of ground nesting bees that utilize down trees for their home. These bees are major pollinators of flowers and flowering shrubs in the forest.

Ants are among the most abundant invertebrates in the forest and many live in down trees and snags. Ants play a critical role in the forest, helping to break down wood, aeration of soil with their burrows, and protection of trees against the onslaught of other insects. One study found that ants killed 85% of the tussock moths that attacked Douglas fir and there are many other examples of how ants protect trees from tree predators.

And it’s not just wildlife that depends on dead trees. A recent review of 1200 lichen species found that 10% were only found on dead trees, and many others prefer dead trees as their prime habitat. Lichens, among other things, are important convertors of atmospheric nitrogen into fixed nitrogen important for plant growth.
Even the charcoal that results from wildfires burning up trees is important for soil productivity, helping to increase soil nutrients, water-holding capacity, and as a long-term storage mechanism for carbon.

Most beetle and wildlife events do not kill all the trees. Instead, they create a mosaic of age classes that actually increases biodiversity. Contrary to the popular opinion that beetles “destroy the forest” and fires “sterilize” the soils or create biological deserts, several recent studies have concluded that both beetle killed forests and the burned forests that result remain after stand replacement wildfires have among the highest biodiversity of any habitat type.

Notwithstanding, the fact that much new research suggest that both thinning or biomass removal are often ineffective at slowing or stopping large fires or insect outbreaks because these events are primarily driven by climatic/weather factors rather than fuels, there is the issue of whether the cure is worse than the so-called disease.

Logging, thinning, biomass removal and other forest management introduce all kinds of negative impacts to the forest ecosystem from the spread of weeds to soil compaction to alteration of water flow, disturbance to wildlife, creation of new ORV trails, increases in sedimentation, that all lead to the degradation of the forest ecosystem itself. Most of these negative impacts are ignored or glossed over by proponents of thinning and biomass removal.

In short, current efforts to thwart, and stop beetle outbreaks and wildfires create “unhealthy forests”. In fact, nearly everything that foresters do from thinning forests to suppressing fires degrades and impoverishes the forest ecosystem. Forest “management” is so focused on trees and wood products, that it represents a critical failure to see the forest through the trees.

Interview Ecological Value of Wildfire

Logging, thinning would not curtail wildfires

Guest Viewpoint


Logging, thinning would not curtail wildfires

By George Wuerthner

Published: Dec 26, 2008 09:26AM
Opinion: Editorials & Letters: Story

Kathy Lynn’s guest viewpoint in the Dec. 17 edition of The Register-­Guard about wildfires and protecting communities was full of flawed assumptions, and consequently flawed solutions.

Lynn correctly noted that acreage burned by wildfire has increased, but she implied that somehow this was a result of “unhealthy” forests — and her implied solution is more logging.

Unfortunately in ecology, what seems obvious is not always accurate. Remember, the sun does appear to go around the Earth.

Contrary to common opinion, large blazes are not driven primarily by fuels, but by climatic conditions. When you have high winds, high temperatures, low humidity and severe drought, you have the right ingredients for large fires.

Not surprisingly, the past decade has been a period of severe drought, high summer temperatures and low humidity. Those conditions have been coupled at times with high winds — so naturally we would expect more large blazes.

Such weather-driven blazes are unstoppable and go out only when the weather changes — not because of a lack of fuels.

Although we are seeing more charred acres in recent year, the idea that this trend is unnatural is skewed by our limited time perspective.

The years between 1940 and late 1980s were moister and cooler than, say, the turn of the century or in the past decade. Unfavorable conditions for fire ignitions kept the annual acreage of wildfires down to historically low levels.

However, if you go back even to the turn of the century, you will find that tens of millions of acres burned annually — including a single fire in Idaho and Montana that in 1910 charred more than 3.5 million acres. One researcher in California recently estimated that prior to 1850, an average of 5 million to 6 million acres burned annually in California alone.

Healthy ecosystems burn, and often burn by the tens of millions of acres. The spate of large wildfires we are experiencing now are not “abnormal” or an indication of “unhealthy” forest. Rather, we are seeing the natural response of a healthy forest ecosystem.

Given that wildfire was so common for thousands of years, it is not surprising that recent research shows that wildfires, particularly severe wildfires, increase biodiversity.

If anything, we probably need more wildfire, not less. With global warming we will probably get it, as vegetative communities adapt to new climatic realities.

Another surprising finding is that mechanical fuels treatment, commonly known as logging and thinning, typically has little effect on the spread of wildfires. In fact, in some cases, it can increase wildfires’ spread and severity by increasing the fine fuels on the ground (slash) and by opening the forest to greater wind and solar penetration, drying fuels faster than in unlogged forests.

Although we are really unable to stop fires, nor prevent their spread by logging and thinning, that doesn’t mean we need to let fire burn down homes.

Research by Jack Cohen at the Missoula Fire Lab in Montana has found that the most effective strategy for protecting homes and communities is accomplished by reducing the flammability of homes. Replacing wooden shingles with metal roofs, removing firewood from around a home, keeping gutters free of debris and other simple measures can significantly reduce the likelihood that a home will burn.

Logging the forests is not the answer to protecting our communities from wildfire, nor does the sun circle the Earth.

George Wuerthner is a part-time resident of Eugene. He is an ecologist, and the author of 34 books, including “Wildfire: A Century of Failed Forest Policy.

Logging not the Answer--A Response to Ellen Simpson

The December 15th Great Falls Tribune editorial by Ellen “No Brainer” Simpson of the Montana Woods Products Industry titled “Red and Dead” reminds me of the scare tactics of the Cold War Era when “better dead than Red” was the motto of some right wing fear mongers.

Throughout her editorial she used fear of fire as her major theme and asserted that it was a “no brainer” that logging was the cure. Towns are going to burn down if we don’t log the forests. People are going to be unemployed if we don’t log the forest. Hikers will be hit by fallen trees if we don’t log the forests.

More than that, she demonstrated that she didn’t use her brain or at least isn’t aware of some of the recent research on beetles, wildfire, and thinning.

It is only the ignorant or those with an agenda to profit from logging that sees wildfire and/or beetle killed forests as “unhealthy”. Unfortunately there is a lot of ignorance being spewed forth by the timber industry trying to exploit fear of fires and beetles.

As is typically the case in ecology, the truth is often the opposite of what seems intuitive. (Remember the world does appear flat.) Contrary to what might seem obvious, logging forests does not stop the kinds of large fires she envisions will engulf Montana communities.

Climate, not fuels, drives large fires. Under conditions of extreme drought, low humidity, high temperatures and high winds, fires are unstoppable. It doesn’t matter whether you have thinned, or even clearcut the land, any residual vegetation will burn and burn well.

I attended the Pacific Coast Fire Ecology Conference a few weeks ago where at least four different presentations showed recent research that documented in one fashion or another that mechanical thinning (i.e. logging) failed to stop fires and/or in some cases actually increased fire severity. Researchers found that logging, by leaving behind fire fuels on the ground, as well as opening up the forest to greater wind penetration and solar heating, can even assist fire spread and increase tree mortality.

If logging were able to stop fires, the Jocko Lake, Black Cat, Chippy Creek, Fish Lake and many other well known Montana fires would have never gotten large enough to make headlines since all burned through areas that had been previously logged and/or thinned.

And while Simpson tries to suggest that wildfires are somehow “bad’ for forest ecosystems, some recent studies suggest that biodiversity is highest in recently burned forests, particularly those with severe fires. From an ecologist’s perspective (and the forest ecosystem), dead trees are an important ecological component of a healthy forest ecosystem.

As for beetle-killed trees increasing fire hazard, again what seems intuitive is not quite what it seems. There is a growing body of scientific literature that finds little correlation between bark beetle-killed trees and wildfires.

Fires don’t burn because there are dead trees. To get the big fires we read about in the papers, you need a convergence of an ignition with severe fire weather conditions of wind, drought, high temperatures and low humidity. These kinds of weather conditions are relatively rare—which is why, for example, large wildfires in Yellowstone’s lodgepole pine forests only occur on average every 300-400 years.

Thus the probability that any particular stand of bug killed trees will burn is small during the few red needle years immediately after a bug kill when they are most vulnerable to fires. In fact, logging a stand of bug killed trees will actually increase the spread and intensity of any fire that should ignite by creating more slash on the ground than if you leave it alone.

Some recent scientific studies back up that contention. Researchers in Yellowstone found only a small relationship between beetle killed trees, and fire—and in one instance found that a recent beetle kill stand apparently had zero chance of increased burning. Another study in Alaska looked at the charcoal/pollen record going back 2,500 years, and could find no relationship between beetle outbreaks and wildfire.

The reason for this has to do with several factors. First, once the red needles and small branches fall off a tree—typically after its first winter--its flammability goes way down. Big upright standing logs just don’t burn that well. It’s the fine fuels that carry a fire as anyone who has tried to make a campfire knows.

Contrary to what you might think, very dry green trees are more flammable than a dead beetle killed tree. Under severe drought conditions the wood in live trees can become as dry as kiln dried lumber, yet still possesses fine fuels of small branches and needles which contain flammable resins.

As for beetles destroying the forest, a recent study found that bark beetles actually increase biodiversity in forest ecosystems, so from the forest ecosystem’s perspective are a welcome natural process.

If protecting Montana communities is the goal, research by Jack Cohen at the Missoula Fire Lab has shown that reducing the flammability of homes is the best and most cost effective strategy for reducing fire risk. Measures like metal roofs, removing wood piles from homes, and other tactic that any individual homeowner can do dramatically increases the chance that a home will survive even a stand replacement blaze.

Unfortunately, forest ecology is not as straight forward as some might suggest, and Ellen “No Brainer” Simpson hopes you don’t use your own brain in thinking about complex ecological issues.

Rethinking Forest Health

George Wuerthner

I just read through a portion of the Beaverhead Deerlodge National Forest (BDNF) revised plan. Among the major components of the plan is support for “vegetation management,” a euphemism for logging. The BDNF plan calls for “treating” its forests by logging to “restore” its ecological health. It has become commonplace for the Forest Service to justify logging for forest health reasons instead of timber production. We no longer log just to get the raw material for lumber and profits for timber companies. We log the forest to restore ecological health, or so the agency suggests.

I personally don’t believe that the BDNF staff is purposefully using “forest health” as an excuse to log. There is a wide-spread assumption among many forest ecologists that past forest management, including past logging, along with fire suppression, has radically altered our forests. However, the agency may be unaware of more recent research that calls into question many of these previous assumptions about forest condition and health.

Even if the assumptions about forest condition are correct, that doesn’t mean that logging can actually restore the presumed “historic range of variability.” One could restore ecological health by permitting more fires to burn, and by the use of more prescribed burning. Since this doesn’t produce profits for the timber industry, the agency is under a lot of pressure to cut trees instead of using less intrusive means like prescribed burning and wildfire as a means of restoring the presumed forest conditions. To its credit, in its Alternative 3 of the forest plan the BDNF does recommend exactly that prescription—more wildfire and prescribed burning and limited logging. Unfortunately, for the public, Alternative 3 is not selected by the agency as its preferred alternative.

The problem for anyone advocating “restoration” is that we have few references about how the forest looked a hundred years ago. There are some historic photographs that provide a valuable perspective, but whether these represent just a point in time and at a particular spot, or are characteristic of the forest as a whole is unknown. Furthermore, there is always the potential for a selective bias in the choice of photographs by the researcher seeking to find evidence for a change in forest condition and composition.

The same can be said about written accounts. When someone asserts that the forests were so open they could ride a horse through them could again reflect a bias in the observer who either selected the easiest pathway through the woods, avoiding other denser forest stands, or even a failure to note when the forests encountered were densely forested. Also there is always the chance for researcher bias that ignores some references to forest condition, in favor of descriptions that fit one’s preconceived notions about how the forest appeared.

The further back in time you go, the murkier the record. Most ecologists must rely upon reconstruction of past “historic conditions” by proxy. One popular method involves looking at fire scars on trees, and trying to determine past fire intervals. The assumption is that low intensity fires do not kill trees, but rather leave a record of their occurrence by a scar. By reading the intervals between such fire scars, researchers can reconstruct past fire occurrence and severity and make some assumptions about the historic look of these forests. However, a recent review of this method by a number of researchers has called into question the validity of many of these studies.

For instance, William Baker from the University of Wyoming and colleagues did a review of fire history studies in ponderosa pine forests and found that nearly half of them depended upon only one or two trees. Such a small sample size is suspect. Furthermore, even when a larger sample is used, there is a tendency for fire researchers to sample trees where there is an abundance of fire-scarred trees. However, such a bias in sampling may not represent the historic conditions of the forested landscape as a whole. Baker’s research suggests that the occurrence of stand replacement fires may have been greater than previously assumed, even for low elevation dry forests.

Another study done by Forest Service researcher Paul Hessburg and associates looked at the temporal patterns of eastside forests in the Cascades. He started with the assumption that past conditions would be reflected by the stand composition of the present forest. Using randomly selected air photos to review forest stand composition, he determined that there was little evidence for so called “light, low intensity” burns or “open park-like” forests in dry low elevation and moist mixed forests as presumed. Rather partial and stand replacement fires appeared to be the norm—even before fire suppression was effective and presumably created a “fuels build up.”

A third study in Colorado done by Dominick Kulakowski and his associates critiqued the Forest Service’s assumption that there was wide-spread “decline” in aspen. Kulakowski was fortunate in finding a highly detailed and accurate 1898 map of forest type and occurrence of recent burns for a portion of the Grand Mesa area of Colorado. Digitizing the map, and then comparing it to the present vegetation type for the forest, he was able to determine that relative to the late 1800s, a larger portion of the landscape was covered with aspen today than a century ago. A rash of fires near the turn of the century as a result of more favorable climatic conditions for fires (i.e. drought), as well as burning by sheep herders, miners, and other settlers contributed to an increase in aspen throughout the 20th Century. So measured against people’s recollection of aspen abundance in the recent past century, there had been a decline in aspen. But what Kulakowski’s research showed is that the current abundance of aspen was not outside of the historic range of variability—and conifer cover was actually greater a hundred years ago than today.

A fourth study of wildfires in the northern Rockies by Penny Morgan, of the University of Idaho, found one more piece of evidence that can be used to question the assumptions about “historic range of variability.” She mapped known wildfires on national forests in Idaho and western Montana from 1900 through 2003. She found the majority of all large fires occurred in just 11 fire years. These fire years coincided with extensive drought. The first six big fire years occurred prior the mid-1930s and the last five years have been since 1988—the year that much of the Yellowstone ecosystem burned. Between the 1940s through the late 1980s, moister conditions resulted in virtually no large fires in the entire region. This has major implications for our assumptions about fire suppression and fuels.

Many people use the recent past as their point of reference. In other words, people talk about the large fires we are experiencing today as compared to the 1940s, 50s, 60s and 70s and presumed that the reason has to be a consequence of greater fuels. But what is intriguing about her research is that six of the large fires occurred long before anyone can claim that fire suppression was responsible for a “fuels buildup.” No one can reasonably assert that fire suppression and fuel buildup was responsible for the huge 1910 Burn that raged across more than 3 million acres of northern Idaho and western Montana. Drought and wind drove those fires, as it has all recent big fires.

The more recent spate of large fires in the 1990s and 2000s are attributed to “fuel buildup” as a consequence of this fire suppression. However, the recent period of large fires also coincides with historically severe drought conditions across the West—the kind of climatic conditions that has always driven large blazes. Severe drought and overall warmer temperatures are also responsible for widespread beetle outbreaks. Beetle experts, however, do not see the large die-off of trees due to beetles as out of the ordinary—and many assume that such large scale beetles outbreaks have occurred in the past, again calling into question the assumption that our forests are “unhealthy.”

Temporal scale is an important factor in how we view current conditions—the longer the time frame of reference, the less current conditions seem unnatural. A study by Boise State University professor Jen Perce and colleagues looked at fire frequency and scale among ponderosa pine forests along the Payette River in Idaho. Using the geological fire history recorded by charcoal buried in soil sediment, she concluded, contrary to popular perception that low intensity blazes are the norm for low elevation dry forests, when viewed over longer time scales, climatic conditions like drought has led to significant stand replacement fires on occasion, even in ponderosa pine ecosystems.

What do all these studies and others suggest about the presumed “historic range of variability”? The message I take from these studies is that climate controls big fires and, when viewed on a landscape scale, our forests may not be out of balance as presumed. In fact our forests are very healthy and what we are seeing with both large blazes and large scale beetle outbreaks are within the “norm” for these forests if climatic conditions are taken into account. The large fires we are experiencing are “resetting” the ecological parameters of the region. There is no need to “restore” forest health—the forests are perfectly healthy and are restoring themselves—without the help of the timber industry, thank you.

Furthermore, even if it can be proved that some forests are somewhat out of “balance” that doesn’t necessarily mean that intrusive logging is necessary or can restore forest health, especially since logging has many other negative impacts that are often ignored or glossed over. These include the creation of access roads that decrease habitat security for wildlife, act as vectors to spread weeds, not to mention are a major source of sedimentation into streams (sedimentation from fires is short lived—while roads “leak” sediment for decades).

Logging operations seldom leave as many snags as naturally occur as a result of fire or beetles. Logging also removes snags which are critical to the survival of many species—for instance; more than a third of all birds in the northern Rockies are cavity nesters, not to mention use of snags by a host of other species from bats to snails. Plus, logs charred by fires take longer to decompose and last longer as a structural component in the ecosystem—with long term consequences for wildlife and nutrient flows. The presumption that logging “emulates” nature is a bunch of timber industry propaganda.

Finally, new research is calling into question the other major justifications for logging which includes the assertion that logging can stop or reduce large fire risk and/or insect outbreaks. Logging does not affect the conditions that drives large blazes namely drought, high temperatures, low humidity, and, most importantly, wind. In fact, there is even evidence to suggest that thinning the forest can substantially exacerbate these conditions leading to increased solar drying of fuels, and permitting greater penetration of wind. Even a five mile an hour increase in wind results in an exponential increase in fire spread. And removal of competing trees, leads to rapid regrowth of shrubs and smaller trees that are more flammable. The best way to reduce fire risk to communities is to fire-proof homes, not the forest.

Circling back to the BDNF plan, all of this research calls into question the Forest Service assumptions about what is “normal” for the BDNF as well as many other forests in the region. It is possible that the Forest Service assumptions about the forest conditions are accurate. On the other hand, there is more than a reasonable likelihood that our forests are well within the “historic range of variability” and need no intrusive management other than to get out of the way and allow fires, beetles, droughts, and other normal ecological processes to operate.