Four Points to consider when thinking about forest fires
1. Every Forest is Different
Some forests, like the lodgepole forests in the Rocky Mountains and Yellowstone National Park (as shown in the photo at the top of this page) have long fire return intervals, are naturally dense, and are filled with a significant amount of woody material.
In contrast, dry ponderosa forests in the Southwest and mixed-conifer forests in the western Sierra Nevada have frequent, mixed-severity wildfires that burn with a mixture of high-severity (most trees are killed) and low-severity (most trees are only scorched). Past fire suppression has caused many of these forest to miss several fire cycles, leading to the build up of vegetation in some locations (see #4 below).
Forests above 7,000 feet are sparse, having fire return intervals on the order of centuries. Other forests, like those in the Pacific Northwest, are so moist that huge trees and dense understories of ferns and shrubs are the norm (prior to industrial logging).
A few forest types are shown below. Click on the photo to see the larger version.
Natural fires are infrequent on most western landscapes. Contrary to the view that fires are supposed to burn frequently, everywhere, the reality is that most ecosystems in the West have long natural fire return intervals. Chart lists ecosystems with naturally long fire return intervals. Click to enlarge.
Sparse forests of high elevation
High Sierra Nevada. The natural time between fires is on the order of centuries.
Jeffery pine grove of about 5 acres in the Sierra Nevada. This is the "open park-like" forest some promote as the natural condition of all forests. It only occurs naturally in small areas.
A wall of wood in the Pacific Northwest, that would eventually become Olympic National Park. Unfortunately, the trees pictured did not survive the logging industry and mismanagement by the US Forest Service.
A post fire snag forest in the low elevation, western Sierra Nevada. This habitat provides an incredibly rich, biodiverse environment. It was scheduled by the US Forest Service to be salvaged logged until it was stopped by a lawsuit.
Dense, lodgepole pines in Yellowstone National Park. High-intensity, large fires are the natural pattern.
Artificial tree plantation. This is what fire officials and foresters often describe as the preferred forest. No shrub understory, trees spaced 10-20 feet apart, and little biodiversity.
2. Logging and Over-grazing
Historically, many Western forests have been severely damaged by industrial logging. Timber companies would first search out and cut the largest trees. Later, huge areas were clear cut. Livestock were often brought in afterwards and used to clear whatever habitat remained. Sheep herders and cattle ranchers also overgrazed forested landscapes, causing significant soil damage and removing the grasses that would have carried low-intensity surface fires.
Consequently, large areas were opened up. With the rich soil and ample rain, forests regenerated with massive numbers of trees. This was the origin of the so-called "dog-haired" thickets and overly dense forests often mentioned in the media.
Ironically, this damage is usually ignored in the forest fire discussion. Instead, the blame for what some claim as over-stocked forests and the large number of dead trees is directed at government efforts to suppress wildfire. Even fire officials, the ones who do the suppression, blame themselves. While fire suppression has indeed added to the ecological imbalance, it was, and remains, the greed of extraction industries like logging and ranching that is the actual source of the problem.
3. Climate Change
Global climate change is raising temperatures in many forested areas in North America. Higher temperatures contribute to increased tree mortality, lengthening of fire seasons, and increasing the number of large, high-intensity fires.
4. Fire Suppression Fallacy
Some low elevation (below 7,000 feet) mixed-conifer forests (like those in the western Sierra Nevada) and dry ponderosa forests in the Southwest have missed natural fire cycles due to fire suppression. However, most forests have not since most natural fire return intervals are a century or more, long before significant fire suppression efforts got underway (see chart above). The actual problem faced by forests that have missed natural fire cycles is not so much about an "artificial" build-up of vegetation, but rather the legacy of past land abuse - clearcut logging, soil disturbance, overgrazing, and the establishment of dense tree plantations (by private as well as USFS managers).
Such disturbance continues today with the addition of chemical herbicides and salvage logging. The notion that recent forest fires are a result of past fire suppression via "fuel" build up is a fallacy. Wildfires are driven by drought, high temperatures, low humidity, and wind, all being exaggerated now by human-caused climate change. Hence, the call to log and clear forests of habitat is more about satisfying timber industry interests than reducing wildfire risk.
Please see the letter of opposition signed by dozens of national and local science and environmental organizations to US Senate Bill 4431 by Daines/Feinstein, a bill that mistakenly calls for increased logging as a solution. Also, an excellent op-ed in the Los Angeles Times provides additional information on this subject: Don't believe self-serving messengers. Logging will not prevent destructive wildfires.
Intensively Managed (logged) Forests Burn Hotter Than Native Forests
“Areas intensively managed burned in the highest intensities. Areas protected in national parks and wilderness areas burned in lower intensities. Plantations burn hotter in a fire than native forests do. We know this from numerous studies based on peer-reviewed science.”*
Look at the photo of the high-severity burn patch from the 2013 Rim Fire. What you will hear from the US Forest Service is that this forest burned at unnaturally high-severity because past fire suppression had created an overly dense forest. The situation is much more complicated than that.
This area shows the ghost of devastation past. All the large, magnificent, fire-resistant trees were logged long ago. Clear cutting likely came next, in several waves. Once the land was barren, a new forest exploded with growth (notice the trees are all about the same size). The only natural portion of this scene is the native shrubland in the lower left corner - now becoming a new, biodiverse pyrogenic habitat, soon to transform into montane chaparral, if allowed.
The US Forest Service's response? Salvage log, tear up the soil, and "reforest" with planation trees. What's the ecologically sound thing to do? Leave Nature alone and stop repeating the same mistakes over and over again. The forest will return in time. We just need to stop pretending it's supposed to happen tomorrow.
A large, high-fire severity patch burned during the 2013 Rim Fire. Notice the size of the trees - all young, all approximately the same age. This is the classic symptom of industrial logging, not fire suppression.
Click image to enlarge.
The Folly of "Salvage" Logging
Ecologist Chad Hanson stands in a Rim Fire snag forest regenerating on its own with ferns, wildflowers and young trees. (Los Angeles Times).
Salvage Logging Causes Significant Environmental Harm
An article in the Los Angeles Times (7/18/18) discussed the folly of pretending that we know better than Nature when the US Forest Service and timber companies promote the practice of post fire "salvage" logging, in this case the fragile post fire, pyrogenic habitat created by the 2013 Rim Fire on the Stanislaus National Forest.
Contrary to what logging advocates claim, nature does not need our help in “restoring” the fragile post-fire forest habitat created by the Rim Fire in the Stanislaus National Forest. Post-fire forests in the Sierra Nevada need to be left alone so they can carry on as they always have by creating rich opportunities for a wild diversity of plants and animals to thrive.
Despite overwhelming science showing that post-fire logging causes significant ecological damage, advocates for the timber industry ignore the fact and use Orwellian double speak ("restore" actually means to log or clear cut) to confuse the public. At times, the disregard for Nature is blatantly exposed. Such occurred during a USFS sponsored field trip through the Rim Fire on May 30, 2019.
When confronted with the fact that thousands of nesting birds would likely be killed in in an upcoming salvage/grinding operation, a board member with the Sierra Nevada Conservancy said that such a thing didn't matter because, after all, birds will be killed in the next fire anyway. See Figures 1 and 2.
When confronting cognitive dissonance, individuals and institutions will reject, rationalize, or ignore the truth.
This is why we filed a lawsuit to stop the forest from being destroyed by salvage logging.
Figure 1. A remarkable pyrogenic habitat created after the 2013 Rim Fire. The US Forest Service designated this place as "unhealthy" and scheduled it to be logged, then planted with plantation trees. Click image to enlarge.
Figure 2. Multiple species of pine and fir emerging in the biodiverse pyrogenic habitat developing after the 2013 Rim Fire, scheduled to be clear cut and crushed by logging equipment.
A rich, pyrogenic, post fire habitat, unlogged, unsalvaged, left alone. Post 2013 Rim Fire, Stanislaus National Forest.
This cheat grass-invaded tree farm was planted after the area was salvaged logged and sprayed with herbicides to eliminate shrubs and natural biodiversity.
Post 2013 Rim Fire, Stanislaus National Forest.
A severely burned forest is not a “destroyed” forest, but rather a habitat restored.
That is not something you are likely to hear during or after the next large forest fire in the Sierra Nevada. It certainly wasn’t during the 2013 Rim Fire in Yosemite and the Stanislaus National Forest. It should have been, however, because the science is clear – severely burned forests provide some of rarest and most biodiverse habitats on earth.
Tahoe National Forest, after the 2008 American River Complex Fire.
Dead Trees, Bark Beetles, and Questionable Claims
about Forest Density
Despite all the panic-filled claims by fire officials and foresters, tree mortality and density in many of our Western forests have not created an ecological disaster nor have these conditions automatically increased fire risk.
Scientific studies have consistently found that trees killed by drought and or beetles (drought is what weakens the trees to allow for beetle attack) do NOT increase risk or severity of wildfire. The most comprehensive study published in the Proceedings of the National Academy of Sciences concluded, "the annual area burned in the western United States has not increased in direct response to bark beetle activity" (Hart et al. 2015). A study from the University of Montana stated "weakening or eliminating environmental laws to allow more beetle timber harvest treatments is the wrong choice for advancing forest health in the United States" (Six et al. 2014).
Other papers concerning tree mortality, beetles, and logging for "restoration" in our forests:
Fire risk and dead trees
"High severity fire was more prevalent in stands with low MPB (mountain pine beetle) mortality due to the higher proportion of live trees (and therefore fine aerial fuels) remaining."
"While research is ongoing and important questions remain unresolved, to date most available evidence indicates that bark beetle outbreaks do not substantially increase the risk of active crown fire in lodgepole pine (Pinus contorta) and spruce (Picea engelmannii)-fir (Abies spp.) forests under most conditions. Instead, active crown fires in these forest types are primarily contingent on dry conditions rather than variations in stand structure, such as those brought about by outbreaks."
"We found no evidence that pre-fire tree mortality influenced fire severity. These results indicate that widespread removal of dead trees may not effectively reduce higher-severity fire in southern California’s conifer forests."
"Though it may seem to some laypersons that a post-fire landscape is a catastrophe, numerous scientific studies tell us that even in the patches where forest fires burn most intensely, the resulting wildlife habitats are among the most ecologically rich and diverse on western forestlands and are essential to support the full range of forest biodiversity."