Warming climate leads to more bark beetles and dead pine trees than drought alone

Research shows that warming shortens the time between beetle generations, supercharging beetle population growth

Pine trees killed by bark beetles
Pine trees killed by bark beetles. Photo by Ethan Miller.

In California’s Sierra Nevada, western pine beetle infestations amped up by global warming were found to kill 30% more ponderosa pine trees than the beetles do under drought alone. A new supercomputer modeling study hints at the grim prospect of future catastrophic tree die-offs and offers insights for mitigating the combined risk of wildfires and insect outbreaks.

“Forests represent a crucial buffer against warming climate and are often touted as an inexpensive mitigation strategy against climate change,” said Zachary Robbins, a researcher at Los Alamos National Laboratory, graduate student at North Carolina State University, and lead author of the paper on beetles and ponderosa pine tree die-offs. “Our research shows that warming shortens the time between beetle generations, supercharging beetle population growth. That can then spur catastrophic mortality in forest systems during drought in the Sierra Nevada and throughout the Western United States.”

In the recently published study in Global Change Biology, Robbins and his collaborators developed a new modeling framework to assess the risk western pine beetles, or bark beetles, pose in many forest ecosystems under climate change. If the effects of compromised tree defenses (15% to 20%) and increased bark beetle populations (20%) are additive, the team determined that 35% to 40% more ponderosa pines would die from beetle attacks for each degree Celsius of warming.

“Our study is the first to attribute a level of tree mortality to the direct effect of warming on bark beetles, using a model that captures both beetle reproduction and development rates and host stress,” Robbins said. “We found that even slight increases in the number of annual generations of bark beetles due to warming can significantly increase tree mortality during drought.”

Using Los Alamos supercomputers, the team modeled bark beetle dynamics and tree die-off during the extreme drought of 2012-2015 and earlier periods. Then they investigated those results using field observations of maximum and minimum temperature, precipitation, tree density, tree mortality, and beetle flight initiation (when fully developed beetles leave their tree of origin) along with lab studies on beetle rate of development.

They found that a quicker rate of producing new generations of off-spring contributed more to killer infestations than did surviving the winter in the absence of cold temperatures fatal to the beetle, yet, surprisingly, the increase in the number of generations was not very big.

“In the Sierra, we saw only about one-third more generations per year, but that really amplified mortality,” Robbins said. “It shows that a small impact in the success of these populations can have a big impact on tree mortality, where we previously thought the beetle needed one whole generation increase to substantially impact mortality.

“These findings should generally apply to many species of pine forests around the West, although the beetle species might be different,” said Chonggang Xu, coauthor of the paper. A senior scientist at Los Alamos, Xu simulates forest-vegetation dynamics in his research.

“Beetle-instigated die-off may cause forests to act as carbon sources to the atmosphere for decades,” Xu said. “Dead trees don’t absorb CO2 but release carbon to the atmosphere. This could potentially raise global forecasts of atmospheric carbon, which has not yet been explicitly considered in current-generation earth-system models.”

The research also has implications for forest management under climate change.

“A mechanistic understanding of the interactions among climate, forests, and disturbances can improve the planning of forest management actions and better predict the effects of climate change on biological systems,” Robbins said.

Older, bigger ponderosas are particularly vulnerable to beetle attacks because their size supports large infestations, Xu said, while younger, smaller trees can survive.

“A diverse forest that combines small and big trees and species diversity, as well, is more resilient,” Xu said. He pointed out that forest management to minimize wildfire risk often removes the smaller trees and preserves the larger ones, “which creates a forest of big trees. Then the beetle comes and the trees could be devastated at the same time.”

Bark beetles kill trees worldwide by chewing through bark and depositing their larvae in the inner bark. An increasing number of beetle outbreaks in the past two decades have devastated forests across the American West, including New Mexico, striking nearly 11 million acres nationwide and threatening the basic structure and ecological processes of some forests.

The beetles exploit the warming, drying climate in the West. When precipitation and temperature remain at historic levels, trees can defend themselves from infestation, but drought often sparks bark beetle outbreaks. That is because water-stressed trees suppress their photosynthesis, close their stoma, and grow more slowly, depleting their carbon storage, which may weaken their defenses.

The life-cycle of the beetle depends on temperature under the bark and in the air. Warmer temperatures reduce the number of beetles killed off by deep winter cold and accelerate and extend the breeding season. Outbreaks finally collapse when bark beetles exhaust the supply of susceptible trees, acutely cold temperatures kill off the beetles, or predators and parasites decimate bark beetle populations.

The study considered historic and contemporary temperature trends in a broad swath of the Sierra Nevada, including several national forests and Kings Canyon, Sequoia, and Yosemite National Parks.

In a new approach, the team used a model of the breeding cycles and population dynamics of bark beetles. The team incorporated this model into a tree-death and insect-attack model, which accounts for the number of bark beetles in flight, the number and size of trees available as hosts, and the drought. The models were validated against data from field observations.

Paper: “Warming increased bark beetle-induced tree mortality by 30% during an extreme drought in California,” by Zachary J. Robbins, Chonggang Xu, Brian H. Aukema, Polly C. Buotte, Rutuja Chitra-Tarak, Christopher J. Fettig, Michael L. Goulden, Devin W. Goodsman, Alexander D. Hall, Charles D. Koven, Lara M. Kueppers, Gavin D. Madakumbura, Leif A. Mortenson, James A. Powell, Robert M. Scheller, in Global Change Biology. DOI: 10.1111/gcb.15927.

Funding:  University of California National Laboratory Fees Research Program at Los Alamos National Laboratory.

From Los Alamos National Laboratory. The paper, funded by taxpayers, is not open source. Copies are priced at $59.


Thanks and a tip of the hat go out to Mike.

Combined, bark beetle outbreaks and wildfire spell uncertain future for forests

Bark beetle outbreaks and wildfire alone are not a death sentence for Colorado’s beloved forests — but together, their toll may become more permanent

Aspen trees regenerate fire beetles
Aspen trees regenerate from their roots in the San Juan range of the Rocky Mountains, amidst many dead Engelmann spruce trees. (Credit: Robert Andrus)

Aspen trees regenerate from their roots in the San Juan range of the Rocky Mountains, amidst many dead Engelmann spruce trees. (Credit: Robert Andrus)

New research from the University of Colorado Boulder found that when wildfire follows a severe spruce beetle outbreak in the Rocky Mountains, Engelmann spruce trees are unable to recover and grow back, while aspen tree roots survive underground. The study, published last month in Ecosphere, is one of the first to document the effects of bark beetle kill on high elevation forests’ recovery from wildfire.

“The fact that Aspen is regenerating prolifically after wildfire is not a surprise,” said Robert Andrus, who conducted this research while working on his PhD in physical geography at CU Boulder. “The surprising piece here is that after beetle kill and then wildfire, there aren’t really any spruce regenerating.”

Andrus’ previous research found that bark beetle outbreaks are not a death sentence to Colorado forests — even after overlapping outbreaks with different kinds of beetles — and that spruce bark beetle infestations do not affect fire severity.

This new research, conducted in the San Juan range of the Rocky Mountains, shows that subalpine forests that have not been attacked by bark beetles will likely recover after wildfire. But for forests that suffer from a severe bark beetle outbreak followed by wildfire within about five years, conifers cannot mount a comeback. While these subalpine forests can often take a century to recover from fire, this research on short-term recovery is a good predictor of longer-term trends.

“This combination, the spruce beetle outbreak and the fire, can alter the trajectory of the forest to dominance by aspen,” said Andrus, who is now a postdoctoral researcher at Washington State University.

For those worried about the future of Rocky Mountain forests farther north, more research is needed on areas burned in the 2020 East Troublesome Fire to understand how the mountain pine beetle outbreak prior to that fire will affect forest recovery, according to Andrus.

The next generation

Each bark beetle species specializes in attacking — and usually killing — a specific host tree species or closely related species. Several species of bark beetle are native to Colorado and usually exist at low abundances, killing only dying or weakened trees. But as the climate becomes hotter and drier, their populations can explode, causing outbreaks which kill large numbers of even the healthiest trees.

spruce seedling fire beetles
An Engelmann spruce seedling survives where few seeds have fallen following spruce beetle outbreak and wildfire. (Credit: Robert Andrus)

An Engelmann spruce seedling survives where few seeds have fallen following spruce beetle outbreak and wildfire. (Credit: Robert Andrus)

These large, healthy Engelmann spruce and subalpine fir trees are the ones that produce the most seeds. When bark beetles kill these trees and then fire sweeps in, the researchers found there simply aren’t enough seeds being produced in the burned areas to regenerate the forest.

Aspens, however, regrow from their root systems. While all three of these higher elevation trees have thin bark and die when exposed to fire, with their regenerative roots underground, aspens can bounce back where conifers cannot.

The researchers focused specifically on areas of forest affected by spruce bark beetle outbreaks, which attack Engelmann spruce, where fires such as Papoose, West Fork and Little Sands burned in 2012 and 2013 in Rio Grande National Forest. They found that for forests that suffer from a severe bark beetle outbreak followed by wildfire within about five years, Engelmann spruce and subalpine fir trees failed to recover in 74% of the 45 sites sampled.

This information will help inform land managers and policy makers about the implications for high elevation forest recovery following a combination of stressors and events.

And it’s more important information than ever. Not only do bark beetle outbreaks leave behind swaths of dead, dry trees — and fewer trees to produce seeds — but the climate is getting hotter and droughts are becoming more frequent, promoting larger fires.

“Bark beetle outbreaks have been killing lots and lots of trees throughout the western United States. And especially at higher elevation forests, what drives bark beetle outbreaks and what drives fire are similar conditions: generally warmer and drier conditions,” said Andrus.

But there is good news: The aspens that may come to dominate these forests can anchor their recovery, and keep forests from transitioning into grasslands.

“Where the aspen are regenerating, we expect to see a forest in those areas,” said Andrus.

The name of the paper that was published January 22, 2021 is “Future dominance by quaking aspen expected following short‐interval, compounded disturbance interaction.” Additional authors on this publication include Thomas Veblen at CU Boulder; and Sarah Hart and Niko Tutland of Colorado State University.

Do fuel reduction treatments increase resistance to insects and drought?

Not always, according to researchers

Prescribed fire at Mount Rushmore National Memorial
Prescribed fire at Mount Rushmore National Memorial, April 29, 2020. Photo by Paul Horsted.

Intuitively we might think that fuel reduction treatments and prescribed fire would lead to more resistance to drought and attacks by beetles. While that is sometimes the case, it turns out that following the extreme 2012-2016 drought in California, prescribed burning increased beetle infestation rates and increased mortality of red fir and sugar pine in an area studied by scientists.

Researchers studied 10,000 mapped and tagged trees in a mixed‐conifer forest following mechanical thinning and/or prescribed burning treatments in 2001 through the extreme drought in California. The work was conducted in the Teakettle Experimental Forest (36°58′ N, 119°2′ W) located in the High Sierra Ranger District of Sierra National Forest, in California’s Sierra Nevada. Elevation of the forest ranges from 1,880 to 2,485 m.

While prescribed burning is an important tool for increasing resistance to wildfire their results suggest prescribed burning does not necessarily also instill drought resistance.

Below is an excerpt from a paper  titled, “Do forest fuel reduction treatments confer resistance to beetle infestation and drought mortality?” It was written by: Z. L. Steel, M. J. Goodwin, M. D. Meyer, G. A. Fricker, H. S. J. Zald, M. D. Hurteau, M. P. North, and published by the Ecological Society of America January 22, 2021.

Management challenges
Density reduction treatments that rely on mechanical thinning alone had neutral to positive effects on conifer survival during the 2012–2016 drought (Figs. 7, 8). The overstory treatment that removed medium to large trees (e.g., ≥25 cm) was most beneficial to residual individuals, suggesting such a strategy could be used broadly to increase drought resilience for some species (i.e., Jeffrey pine and white fir). While removal of smaller trees (e.g., ≤25 cm) may be less effective at mitigating drought mortality, treatments focused on ladder and surface fuels may still be preferred when considering non‐drought objectives such as reducing fire hazard or maintaining wildlife habitat (Stephens et al. 2012).

Prescribed burning appears less effective than mechanical thinning at reducing drought mortality and in some cases can lead to higher beetle infestation and mortality rates (Fig. 8). This is most striking in the case of large sugar pines which died at much higher rates in prescribed burn plots during the drought. The negative effect of burning on tree survival is somewhat surprising given that the fire regime under which these forests developed was characterized by frequent (i.e., 11–17 yr) low‐ to moderate‐severity fire (North et al. 2005, Safford and Stevens 2017), and that the prescribed burn occurred approximately a decade prior to the drought.

Mortality and probability change
Indirect effect of forest treatment on drought mortality. Treatment abbreviations are UU for Unburned/Understory Thin; UO for Unburned/Overstory Thin; BN for Burned/No Thin; BU for Burned/Understory Thin; and BO for Burned/Overstory Thin. Value distributions represent change in probability of mortality relative to controls for two tree sizes. The scale of the x‐axis varies among species. (From the research)

Further, van Mantgem et al. (2016) observed decreased tree mortality associated with prescribed fire elsewhere in the Sierra Nevada following the initial two years of California’s drought, and Meyer et al. (2019) found no difference in mortality between paired burned and unburned plots in red fir forests during the middle and late periods of the drought. The forests Meyer et al. (2019) sampled were at higher elevations than Teakettle where soil moisture is substantially higher and temperatures lower.

The results presented here could be unique to the Teakettle Experimental Forest, but we suspect they are more likely attributable to the historic severity of the 2012–2016 drought. When beetle populations are less than epidemic such as at higher elevations, during moderate droughts, or early in severe droughts, previous fire and its associated reduced density may be neutral or ameliorating for conifer mortality.

Our sugar pine results may indicate a tipping point beyond which the combination of extreme water stress from drought, bark beetle outbreaks, and fire result in increasingly high rates of tree mortality (Nesmith et al. 2015), and subsequent forest structural changes outside the natural range of variation (Young et al. 2020).

These results suggest cautious low‐intensity and small (i.e., stand) scale prescribed burning, as it is often applied by managers, may only benefit forests under short duration drought stress while contributing to higher mortality in red fir and sugar pine during prolonged and exceptional droughts.

High mortality rates of large sugar pines may be related to prescribed fires consumption of deep litter and duff layers that have accumulated around the base of pine species under fire suppression, suggesting removal of litter and duff through raking could protect individual trees. Nesmith et al. (2010) found raking increased survival and reduced bark beetle activity when fire intensity was moderate (<80% crown scorch) and when fuel depth was ≥30 cm. Thus, protecting individual trees of high ecological value may be possible prior to prescribed burns. However, such targeted measures are infeasible at broad scales in fire‐prone landscapes of the Sierra Nevada. In the long run, retaining sugar pine in these pyrogenic landscapes may hinge on fostering sunny, bare mineral soil conditions favorable for sugar pine regeneration and in the future reducing surface fuels on a regular basis.

Infestation probability
Marginal effects on beetle infestation. (C) host species basal area within a 10‐m radius, and (D) whether a tree experienced a prescribed burn treatment. Beetle and tree species abbreviations are jpb for Jeffrey pine beetle; rtb for red turpentine beetle; mpb for mountain pine beetle; eng for fir engraver; pije for Pinus jeffreyi (Jeffrey pine); pila for Pinus lambertiana (sugar pine); abco for Abies concolor (white fir); and abma for Abies magnifica (red fir). For C, thick lines show mean effect estimates with labeled solid lines represent relationships where the 90% credible interval does not include zero. To illustrate the spread of credible effects, 30 model posterior draws are also drawn as faint lines. Note the y‐axis scale differs for (D). (From the research)

Treatment effects on large diameter trees are often the focus of management restoration efforts since these structures have been reduced from past logging, take a long time to develop, and are associated with important ecosystem services (e.g., sensitive species habitat and carbon storage). Treatments using only thinning consistently reduced mortality of large (>75 cm DBH) trees across species, albeit with different effect sizes. For incense‐cedar and especially white fir, there was a greater reduction in mortality for small versus large trees, which are often the target of fuel reduction treatments. Prescribed fire has mixed effects, reducing mortality of large Jeffrey pine and slightly reducing small white fir mortality when combined with thinning, but increasing mortality of large red fir, incense‐cedar, and significantly increasing large sugar pine mortality.

While prescribed burning is an important tool for increasing resistance to wildfire (Stephens and Moghaddas 2005, Prichard et al. 2010), our results suggest such fuel treatments do not necessarily also instill drought resistance. There is general benefit to all species in reducing density, but the means (i.e., mechanical vs. prescribed fire) of treatment matters, suggesting caution in widespread use of fire in drought‐prone areas where managers want to retain large sugar pines and red fir.

Firefighters report “surprising” fire behavior in beetle-attacked lodgepole forests

surprising fire behavior beetle-attacked lodgepole forest fires
The researchers interviewed senior firefighters who worked on 13 wildfires in beetle-attacked areas of Northern Colorado and Southern Wyoming between 2010 and 2012. Image from the research. Click to enlarge.

In 28 interviews of experienced wildland firefighters of seven different agencies in Northern Colorado and Southern Wyoming researchers asked them about their observations of fire behavior in beetle-attacked lodgepole pine forests, with a focus on what they considered surprising from a fire behavior standpoint and how this in turn affected their suppression tactics. The interviews focused on 13 wildfires that occurred during the 2010 through 2012 fire seasons.

Below is an excerpt from a paper written by the researchers:

“The surprises in fire behavior experienced by firefighters during the red phase of post-outbreak forests included an elevated level of fire spread and intensity under moderate weather and fuel moisture conditions, increased spotting, and faster surface-to-crown fire transitions with limited or no ladder fuels.

“Unexpectedly, during the gray phase in mountain pine beetle-attacked stands, crown ignition and crown fire propagation was observed for short periods of time. Firefighters are now more likely to expect to see active fire behavior in nearly all fire weather and fuel moisture conditions, not just under critically dry and windy situations, and across all mountain pine beetle attack phases, not just the red phase. Firefighters changed their suppression tactics by adopting indirect methods due to the potential fire behavior and tree-fall hazards associated with mountain pine beetle-attacked lodgepole pine forests.”

Download the research paper (1 Mb)

Forest Service intends to restore areas in Wyoming with logging, prescribed fire, and building roads

The project would take place in the Medicine Bow National Forest in southern Wyoming

Beaver Creek Fire intensity
Varying burn intensities on the Beaver Creek Fire in the Medicine Bow-Routt NF in Colorado about 1 mile south of the Wyoming state line. The area had large areas of beetle-killed trees. July, 2016. InciWeb.

The U.S. Forest Service has a plan to treat 360,000 acres in the Medicine Bow National Forest in southern Wyoming by logging, thinning, prescribed burning, and building 600 miles of roads. The justification for what they are calling the Landscape Vegetation Analysis project, or LaVA, is to treat areas in the forest with the intention of “restoring forest health”. This area just north of the Colorado/ Wyoming border has been heavily impacted by Mountain Pine Beetles, so it fits the agency’s definition of an unhealthy forest and is considered by the U.S. Forest Service as an undesirable condition.

Landscape Vegetation Analysis project
The areas in the Medicine Bow National Forest north of the Colorado line would be part of the Landscape Vegetation Analysis project.

The Forest Service intends to build 600 miles of roads, clear cut 95,000 acres, selectively cut or commercially thin 165,000 acres, and use prescribed fire, mastication, and hand thinning on 100,000 acres.

Climate change that brought drought and warmer weather has provided a better habitat for the beetles. During normal times their spread is inhibited in the higher elevations by cold winters. Several days with low temperatures of around 35 degrees below zero can knock them back, but if that does not occur the rice-sized insects can come back with a vengeance the next summer.

Beetle-killed trees can be hazardous to firefighters due to the possibility of falling trees and burning snags. And, 5 to 15 years after the outbreak heavy ground fuels make fireline construction difficult. The dead trees can also be problematic near roads, trails, and structures. But a couple of years after the beetle attack and the red needles have been shed, the tree skeletons are less prone to crown fires than green trees. In 2015 University of Colorado Boulder researcher Sarah Hart determined Western U.S. forests killed by the mountain pine beetle epidemic are no more at risk to burn than healthy Western forests. Other scientists have found similar results.

Below is an excerpt from the Washington Post:

Not everyone considers the plan a good idea. Some biologists say science doesn’t back up the efficacy of the treatments proposed, particularly logging and the prescribed burns that the Forest Service calls necessary for lodgepole pine to reproduce and more diverse species to take root.

“They say they are going to reduce fuel loads to limit wildfires, and the literature doesn’t support that,” said Daniel B. Tinker, an associate professor at the University of Wyoming, who has studied the region for 23 years. “We’ve had fires this summer that burned through areas that were clear-cut 15 years ago. Those stands weren’t supposed to burn for 100 years.”

Conservation groups also say the Forest Service truncated scientific review in a rush to meet congressional demands for increased timber production on public lands. For now, the proposal does not specify which parcels would be targeted and where those hundreds of miles of road would be built.

In the Washington Post, article Andy Stahl, executive director of Forest Service Employees for Environmental Ethics, was quoted as saying “Certainly, prescribed burning doesn’t pay its way — it’s expensive at around $100,000 per acre.”

If there is a prescribed fire somewhere that actually cost $100,000 an acre, which is very hard to believe, it is definitely an outlier. The costs vary greatly across the country and by vegetation type. They can be as inexpensive as less than a dollar an acre in Oklahoma, but usually run $10 to $250 an acre.

The federal agencies have had to cut back on their prescribed burning programs in recent years due to budget reductions.

The Forest Service expects to make a decision on the Medicine Bow plan in mid-2019.

Thanks and a tip of the hat go out to Gary.
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Secretary Zinke issues misleading information about wildfire risk

He incorrectly said a beetle infestation leads to an added risk for fire

Beaver Creek Fire beetles intensity
Photo of a portion of the 2016 Beaver Creek Fire in Colorado, an area with heavy beetle kill. One smoke is visible. USFS photo by Andrea Holland.

Today Secretary of the Interior Ryan Zinke tweeted that trees killed by beetles “are an added risk for fire”. This is misleading at best, and incorrect when all of the facts are brought to light.

And as before when the Secretary and the President said “poor forest management” and “environmental radicals” are responsible for the recent major fires in California, the issue can’t be described or solutions offered using just a few words. It is nuanced and complicated, not lending itself to a 280-character conversation.

In 2010 I first became aware of research by scientists that found fire severity decreases following an attack by mountain pine beetles. Since then additional studies have led to a more thorough understanding of the process.

Three factors or characteristics of a beetle-killed forest affect the behavior of a wildland fire.

  1. After a tree is killed by a mountain pine beetle, the needles turn brown or red; this is known as the “red stage”. The dead red needles remain on the tree for one or two years and then fall off. During this period the potential for a crown fire that moves above the ground through the tops or crowns of the trees can increase. After the needles drop the potential for a crown fire is close to zero. A crown fire can’t be controlled. No amount of fire retardant dropped by aircraft, water applied from the ground, or dozers building fire lines will stop it. This is the largest factor to consider when discussing fire behavior before and after a beetle outbreak. After a couple of years, it is easier to control a fire in a beetle-affected forest than one that is green, and this effect lasts for decades. There are other factors to consider also.
  2. After 5 to 15 years the limbs begin to break off a beetle-killed tree and then the top can break off and eventually the remainder of the tree falls to the ground. This adds fuel to the forest floor and can increase the intensity of a fire that burns along the ground. It is easier to control a surface fire, even one burning intensely, than a crown fire .
  3. After a decade or two the potential for individual or multiple tree torching can increase. This involves the burning of an entire standing single tree or multiple trees. These latter two issues, surface fire intensity and torching, add to the challenges for firefighters, but the reduced crown fire potential greatly outweighs the other two.

This can be distilled into what I have called Resistance to Control (RTC) which considers those three characteristics of a beetle-killed forest. One to two years after the insect-attacked tree dies, the RTC increases,  but after that it decreases immediately and remains lower than before the attack for several decades. Eventually live trees replace the dead ones and all three characteristics return to their normal state.

The chart below summarizes these three issues. It is from a paper titled Effects of bark beetle-caused tree mortality on wildfire, written by Jeffrey A. Hicke, Morris C. Johnson, Jane L. Hayes, and Haiganoush K. Preisler. With apologies to the authors of this very good research paper, I took the liberty of adding a Resistance To Control variable (the red line) to their chart.

Bark Beetles effect on fire behavior, multiple studies w-resistance to control

There is still another characteristic of a beetle-killed forest that is important to consider. Pine beetle outbreaks do not automatically lead to catastrophic wildfires. In 2015 University of Colorado Boulder researcher Sarah Hart determined Western U.S. forests killed by the mountain pine beetle epidemic are no more at risk to burn than healthy Western forests. Other scientists have found similar results.

Mr. Zinke referred to a forest with evidence of tree mortality caused by insects as a forest that is not healthy. Insects are part of the ecosystem; they will always be part of the forests. We will never be able to eradicate them, nor should we. The populations of the insects run in cycles. They feed on trees to survive.

In addition, the “dead and dying timber” as a result of fires or insects that Mr. Zinke wants to remove is an integral part of the forest ecosystem. The National Wildlife Federation says, “Dead trees provide vital habitat for more than 1,000 species of wildlife nationwide. They also count as cover and places for wildlife to raise young.”

An article at The Hill November 20 covers how Mr. Zinke and Secretary of Agriculture Sonny Perdue are hoping that the new version of the Farm Bill will allow more logging that among other objectives, “beautifies the forests”, as Mr. Zinke is quoted as saying.

Roy Renkin, a Yellowstone National Park Vegetation Management Specialist, wrote in 2010, “Disturbances like insect outbreaks and fire are recognized to be integral to the health of the forests,” he said, “and it has taken ecologists most of this century to realize as much. Yet when these disturbances occur, our emotional psyche leads us to say the forests are ‘unhealthy.’ Bugs and fires are neither good nor bad, they just are.”

(Here is a link to all articles on Wildfire Today about beetles and fire.)