Kevin Van Tighem Says No
Conservation and nature writer and former superintendent of Banff National Park
Our fight against the mountain pine beetle is doomed to failure. And in fighting this hopeless war we’re actually fighting the things our future most needs: sustainable forest ecosystems and water security.
Alberta earns $100-million per year in stumpage revenues from forestry. But we spend almost half that amount each year on pine beetle control. That’s a direct subsidy back to industry—over half a billion dollars so far. Those forests are on public lands and provide far more than just wood. We rely on them for recreation, wildlife habitat and, most importantly, water. Our economy can survive without timber revenues, but not without the water that comes from those forested hills.
The dense lodgepole pine forests of western Alberta grew in a climate that no longer exists. Periodically renewed by fire, they used to benefit from good soil moisture in the growing season, followed by long, cold winters that killed bark beetles. That 20th-century climate is gone. Winters are milder, summer droughts more frequent, and extreme weather brings damaging winds. Wind-killed trees are good habitat for Ips, Dendroctonus and other bark beetles. Mild winters help beetles survive. And drought-stressed trees are easy to attack and overwhelm.
So the beetles are here to stay. We should manage our forests for the future, not the past. Researchers have shown that those crowded pine forests are already stressed by limited soil moisture. Beetles, by thinning forests, create healthier, vigorous stands better able to survive insect outbreaks. More-open forest canopies reduce the risk of severe wildfires too, by making it harder for flames to spread. Opening up the forest also improves water supply. Instead of getting caught in branches and evaporating, more snow accumulates on the ground. The trees shelter that snow from sun and wind so that it gradually soaks into the ground instead of rapidly draining as it does in exposed logging clear-cuts. That’s good both for trees and for creeks and rivers reliant on groundwater.
As the climate shifts towards one that favours pine beetles, it would also make sense to manage forests for greater diversity: not just pines, but spruce, firs, aspens and poplar. Mixed forests not only resist insect outbreaks, they support more kinds of wildlife. Ironically, pine beetles give us exactly that: open forests with a mix of tree species. They don’t kill all the trees; they don’t even kill all the pines. The most vigorous pines survive amid other species, all spaced more widely because of the dead pines mixed among them.
But what about fire? Research in BC and the Yellowstone has shown that beetle-killed stands are no more likely to burn than live trees. Once needles fall off, dead pines actually resist fire.
At a time of rapid climate change, mountain pine beetles are Nature’s gift to us; they help create the forest ecosystems we need. It’s wrong to waste public money in a futile effort to help private forest companies remain stuck in the last century.
Allan L. Carroll Says Yes
Professor and director of forest sciences at the University of British Columbia
In the late 1990s the most recent mountain pine beetle outbreak began in central BC. Due to a long history of fire suppression creating large areas of homogeneous pine forests and to climate warming enhancing beetle survival, the outbreak rapidly spread to become the largest forest disturbance event in recorded history. Jurisdictions across western North America were forced to make extraordinary decisions regarding management of mountain pine beetle. Decisions of this sort are the responsibility of elected officials, ideally based on balanced assessment of available facts. The responsibility of a scientist, such as myself, is to generate the knowledge to support decision makers. Here, I briefly outline the facts associated with the Government of Alberta’s decision to control the spread of mountain pine beetle and describe some of our learnings on the ramifications of that decision.
In 2006, during the peak of BC’s outbreak, large numbers of beetles were carried eastward by winds and deposited in the forests of central Alberta. These forests contain populations of pine trees that have not evolved with mountain pine beetle. As a result, they’re less resistant to attacks, and once colonized they produce more beetles. This startling fact raised concerns that impacts in Alberta would exceed those seen in BC, where projections at the time suggested 80 per cent of mature pine would be killed. Values considered at risk in Alberta were threefold: economy of the forest sector; resilience of watersheds along the southeast slopes of the Rockies; and the integrity of transcontinental boreal Jack pine. To protect these values the Government of Alberta implemented an aggressive program to reduce the size of the invading beetle population. Given that beetles feed and reproduce beneath the bark, this can only be accomplished by destroying currently infested trees, a very labour-intensive and expensive endeavour.
To date, Alberta has spent over $500-million to mitigate mountain pine beetle impacts. The province’s forest industry is worth $9-billion annually and employs 38,000 workers. Although it’s not possible to place a value on the watersheds of the southeast slopes nor on boreal Jack pine, the $500-million invested over 15 years seems a bargain relative to the value of the forest sector alone—provided, of course, the beetle control program works. Our analysis of the efficacy of the program shows it has protected more than 500,000 hectares from colonization by the beetle. We also project that populations will likely collapse before the end of the decade, as long as control efforts are maintained. Thus, continuation of the ongoing spread-control program seems more than prudent.
Mountain pine beetle is now firmly established in Alberta, and, as in its native range, future outbreaks can be expected. Decision-makers then will be faced with the same difficult task to formulate a response concomitant to the values at risk. Lessons learned from the current outbreak will be invaluable.
Kevin Van Tighem responds to Allan L. Carroll
What’s needed, and missing, from much of the rhetoric around pine beetles, is simple realism. It’s therefore encouraging that Allan Carroll acknowledges the fact that mountain pine beetles are here to stay. Beetle populations, as he points out, benefit from an abundance of vulnerable trees and favourable weather conditions. We now have both.
Alberta’s forest management has created the former, by preventing forest-renewing fires so effectively that many pine stands are now both crowded and aging, as well as by reforesting clear-cuts with monocultures of densely packed and genetically similar pine trees. The changing climate has generated the latter condition. We have, in short, made Alberta a good place for bark beetles.
There are, however, two flaws in Carroll’s argument. The first is his assertion that mountain pine beetle has never been native to Alberta and that our pine trees are consequently more vulnerable to them. This is pure conjecture. There have been times in the past—notably the Hypsithermal period, between 9,000 and 5,000 years ago—when Alberta’s climate was much warmer. There’s no reason not to assume that mountain pine beetles were widespread then. The same beetle species is endemic to the Black Hills of South Dakota, considerably farther east than Alberta. And Alberta’s lodgepole pine have long coexisted with many other species of bark beetle. There’s no reason to assume—and no evidence—that lodgepole pines in Alberta respond to mountain pine beetles any differently than lodgepole pines in BC. Absent any scientific evidence, asserting that our pines are more vulnerable becomes merely rhetoric supporting people looking for more reasons to log.
The second flaw is Carroll’s suggestion that we need to manage pine beetles to protect our watershed resilience. This argument is wrong-headed. “Management” of pine beetles involves, to a large degree, aggressive logging. Logging entails the digging of roads, scarification of soils and removal of standing trees, all of which damage hydrological processes, increase sediment erosion, promote early snow melt and leave the landscape exposed to sun and wind. Pine beetles, on the other hand, open up the forest canopy while retaining intact soils, standing trees (dead and live) and lush understorey vegetation. If Alberta were truly concerned about managing our forests for watershed health, we would reform logging practices so that logging left forests looking and functioning more like the kinds of forests that pine beetles give us—for free.
The war on beetles makes sense only if one sees forests primarily as economic resources, not as living ecosystems.
Alberta’s watersheds are certainly in trouble—but large-scale logging is a big part of the problem, not any part of the solution. More logging is exactly the opposite of what we need.
It’s certainly legitimate to worry about what will happen when mountain pine beetles spread into Jack pine stands farther east across the boreal. What’s missing, however, when foresters argue for more logging to prevent that from happening, is a realistic assessment of what drives the spread of beetles. Climate change trumps everything. There’s nothing we can do, at this point, to prevent the spread of pine beetles in a hotter, drier boreal.
Any species that undergoes episodic population explosions also experiences population crashes. Carroll is right to predict that, by the end of this decade, pine beetle numbers will have declined. What is less persuasive is his assumption that the decline will be the result of Alberta’s aggressive logging response. Experience in BC has shown that loggers chase beetles across the landscape, leaving clear-cut messes behind while failing to catch up with the bugs, but are happy to take credit for the inevitable natural crash in the beetle population. Why? Because it gives them licence to “save” the forests all over again next time, by wreaking harm that far outweighs the purported damage being done by a native insect.
The war on pine beetles makes sense only if one sees forests primarily as economic resources, not as living ecosystems, and only if one assumes that climate change isn’t real. But forests are dynamic ecosystems that respond to climate and other changes by way of natural disturbance processes such as fire, trees being uprooted by wind, and insect outbreaks. Those natural adjustments shape new forest communities that continue to protect watersheds, provide wildlife habitat and sustain reasonable levels of resource development. And climate change is, unfortunately, as real as it is now irreversible.
That’s why pine beetles are here to stay. They are nature’s elegant and predictable way of helping our forests adjust to change. They aren’t just natural; they’re necessary. The fight against pine beetles, on the other hand, amounts to doubling down on the unsustainable harm already being caused by those who look at forests and see only wood products.
Allan L. Carroll responds to Kevin Van Tighem
Kevin Van Tighem outlines a long-term management vision intended to promote the resilience of Alberta’s forests in the face of global change. The case he makes is irrefutable and I support it wholeheartedly. Where I am forced to take issue is with his assertion that management of the mountain pine beetle is doomed to failure. I have encountered this belief often in the decades I have worked with eruptive forest insects. It arises from misconceptions regarding the complex population dynamics of the insects, their interactions with the environment, and legacy impacts of past forest-management decisions.
The mountain pine beetle is a bark beetle, meaning it feeds and reproduces in the tissues beneath the bark of its host trees. Successful colonization and subsequent reproduction necessitate tree death. It is an eruptive species characterized by occasional outbreaks in pine forests throughout its historical range west of the Rockies. Between outbreaks, the beetle exists in very low-density populations. Beetles from these populations avoid healthy, vigorous trees due to their effective resin defence systems that can repel low-density attacks. Instead, they infest and kill moribund trees with impaired defences. These endemic populations contribute to the overall health of the remaining forest.
Epidemic beetles threaten the many ecosystem services provided by mature pine forests.
Beetle behaviour changes when conditions allow populations to grow. Now the beetles preferentially attack and kill large, vigorous trees that contain higher-quality tissues within which larvae develop. These epidemic beetles use pheromones to co-operatively mass-attack trees, overwhelming their defences. The larger the beetle population, the more trees that are killed in an epidemic. No tree is completely immune to attack by epidemic beetles. Like BC, the pine forests of Alberta have been subjected to aggressive fire suppression for decades. This has made them age unnaturally, creating vast areas of mature trees susceptible to epidemic mountain pine beetle. The occurrence of epidemic beetles in Alberta, as in BC, threatens the many ecosystem services provided by mature pine forests—unless the rate of spread and impacts is mitigated.
Alberta was afforded an invaluable lesson by BC’s slow response to the mountain pine beetle eruption that began in the late 1990s: Impacts of a burgeoning outbreak can be mitigated only by early and aggressive actions that reduce beetle populations. BC’s delays led to an unprecedented outbreak that caused huge socioeconomic and ecological impacts that will surely resonate for decades. With the outbreak spreading north and east in BC, Alberta prepared for the likely invasion. When it came, the province implemented an aggressive control program intended to find and destroy as many newly infested trees as possible each year. A recent assessment of the Government of Alberta’s “slow-the-spread” program by my research group has shown that the potential area of invasion by epidemic mountain pine beetle has been reduced by approximately 70 per cent to date.
The assertion that the slow-the-spread program is “doomed to fail” is only valid if this effort and expense is required in perpetuity. But outbreaks don’t last forever. The slow-the-spread program, as its name implies, is intended to mitigate impacts until the outbreak naturally collapses. In all previous outbreaks in BC, epidemic populations collapsed in 10–15 years. This is primarily due to the tendency of epidemic beetles to kill large trees so quickly that they exceed their ability to find and colonize new ones. In Alberta the evidence suggests populations are already falling, and collapse is projected within a few years. Management is in fact succeeding in protecting large areas of pine forests from invasive mountain pine beetle. As a result, susceptible watersheds, wildlife habitat and recreational areas have been sheltered from large amounts of tree mortality. Continuing the slow-the-spread program until beetle populations collapse will ensure forests’ protection, at least in the short term.
Van Tighem is correct that the mountain pine beetle is now a permanent resident of Alberta’s pine forests, and that climate change has created conditions that favour its survival. In combination with the limited defences of evolutionarily naïve pines in Alberta, this makes future outbreaks very likely. If the ongoing slow-the-spread program can be maintained for the next several years, then I’m in complete agreement with Van Tighem that forest management efforts must refocus on tactics that promote resistance and resilience to future disturbances of all kinds—including the next mountain pine beetle outbreak. The ability of forests to be resistant and resilient to disturbance is dependent upon species diversity and landscape heterogeneity. This creates “spatial insurance” for viable ecosystems to retain ecological processes and deliver ecosystem services in the face of global change.
