Testimony of Dr. Peter Kolb on Mountain Pine Beetle
Peter Kolb. 2009. Testimony of Dr. Peter Kolb, Montana State University, before the House Natural Resources Subcommittee on Water and Power Hearing on Mountain Pine Beetle: Strategies For Protecting The West, June 16, 2009.
Full text [here]
Selected excerpts:
My name is Peter Kolb, and I am the Montana State University Extension Forestry Specialist and an Associate Professor of Forest Ecology and Management at the University of Montana College of Forestry and Conservation. I’m here today speaking on behalf of the Society of American Foresters (SAF), an organization of over 15,000 forest managers, researchers, and educators. I’ve been a SAF member for 27 years.
I am here today to offer you my testimony with regard to the bark beetle situation across western forests with specific reference to the conditions across the Montana with which I am most familiar. My perspective is not that of an entomologist, but that of a forest ecologist and management specialist whose main work objective is to help implement the results and conclusion of scientific research into practical working applications. I work in both academic circles as an applied researcher and educator, and in the forest practitioners’ realm, which gives me the opportunity not only to conduct relevant research, but to examine the effects of forestry applications. Just three days ago I returned from a week of working with family landowners and the Cree and Chippewa tribes of central Montana where we examined the forest conditions there and the effectiveness of various forest practices in combating a mountain pine beetle outbreak in the Bearpaw Mountains.
Bark Beetles
The bark beetle outbreak we are experiencing across the entire western portion of North America is the result of multiple ecological factors converging at the same time. Its occurrence is not a surprise for foresters across western forests as the current expansiveness of bark beetle activity has been building for many years. Bark beetles such as mountain pine beetles, one of the main culprits in the current outbreaks, have been extensively studied since the mid 1970s. Its life cycle and ecology are very well understood. It has been a natural part of western forests for millennia and its population cycles are fairly predictable. Under what we would characterize the average forest and climatic conditions of the past century it exists as a chronic population within pine forests, colonizing and killing trees that are unable or incapable of defending themselves due to a variety of physiological, genetic or environmental factors. It may be considered analogous to wolves circling a herd of caribou, culling out the weak, unfit and injured. As with any species, bark beetles have numerous pests and predators themselves including a variety of predatory beetles, wasps, nematodes, mites, fungal diseases, and larger predators such as bark gleaning birds and woodpeckers. Depending on the populations of these predators and pests, chronic bark beetle populations might be kept in check.
… The greater the suitable host tree number, the greater the potential food source and thus the larger the population of bark beetles that can develop. Likewise, the greater the percentage of host trees that are similar in age and size, the greater the probability of bark beetles successfully attacking and colonizing them at the same time.
A landscape such as Yellowstone National Park, that had a large acreage burn catastrophically in 1988, will develop an even aged forest of fire adapted lodgepole pine that are all similar in size equivalent in expansiveness as the area of disturbance. When these trees reach 90-100 years of age, they will mostly become suitable host trees at the same time that under the right climatic conditions can allow an epidemic of bark beetles to develop once again. The epidemic will then persist as long as there are host trees within flying distance of beetles and the climate remains favorable. The same is true, for example, of Colorado and Wyoming’s lodgepole pine forests. By and large, these forests are mature, even age forests of lodgepole pine stressed by drought and high densities of trees combined with warmer temperatures that foster mountain pine beetle population explosion. …
Mature forests with dense canopies have the additive effects of transpiring more water than forests of younger trees with less needle area, and intercepting rainfall and snowfall in their dense canopies that evaporates back into the atmosphere before having a chance to enter the soil where trees can absorb it. The additive impacts of greater water and energy production requirements, less soil water recharge, and limited space for photosynthetic (needle) area leads to significantly weakened trees. At this point the trees in this condition represent a large food source without any defenses, the perfect target for bark beetles and a host of other tree pests and pathogens. …
German Forests
Across central Europe forests have been harvested intensively and continually for over 2000 years. Many countries there, notably Sweden, Germany, Austria, France and Switzerland have developed forest management practices that maintain forest productivity, biodiversity, scenic and recreational beauty, and that have greatly limited catastrophic disturbances including bark beetle outbreaks.
As an example, the country of Germany has roughly the equivalent land area and forested area as Montana. A greater oceanic effect provides for a slightly milder climate and more evenly distributed annual precipitation. Tree growth rates can be twice as high there as in Montana. Whereas Montana has approximately 950,000 permanent residents, Germany has 83 million residents. Hiking and nature appreciation is a national pastime, and a large proportion of German forests have a primary nature reserve or biodiversity protection designation. Important to note is that forest management including tree harvesting is not viewed as a barrier to such objectives, but rather a tool to help achieve desired conditions for rare and endangered species and recreational quality. …
On an annual basis Germany harvests 12.6 billion board-feet equivalent of wood, Montana over the past decade has annually harvested an average of 750 million board-feet, most of which has come from private lands, not federal lands even though the later accounts for 67% of the Montana forest land base. To put this in perspective, the height of the timber harvest from [US] national forests was roughly 12 billion board-feet in the 1980s. Now the entire harvest off of national forests is roughly two billion board-feet. For Montana, as many other western states, the repercussions have been devastating to the wood products industry, forestry and logging professions. …
Bark beetles are a common problem in all forests in Germany for the most prevalent tree species, yet in the past decades bark beetle epidemics have not occurred, mainly because they have been prevented. The one exception is in the Bavarian National Park, were forest management was excluded as the purpose of the park was for nature to run its course without human interference, and for the dominating native pure spruce forest to grow into ancient old growth character. In the late 1990’s a spruce bark beetle population started to build in this forest. In the past decade it has killed 80% of the trees across 60% of the park and is expected to decimate the rest in the next five years. This past year, the Bavarian government agreed to allow foresters to start implementing measures to attempt to control the epidemic as it is now spilling out of the park onto private forested lands. …
Management Solutions for the US?
Can these management tactics also work for forest across the western United States? Our understanding of tree and beetle biology for our afflicted areas and species, as well as experiential knowledge certainly matches what German foresters have to work with. Multiple studies have shown that thinning forest stands to alleviate the impacts of light and water competition on tree vigor while leaving what appear to be the best trees results in less successful bark beetle attacks (Schmid et al. 2007). It has also been postulated that the greater heating from sunlight increases stress on bark beetles as they seek out trees. Increasing the diversity of tree species in forests that are primarily monocultures, such as the situation we see in Wyoming and Colorado with lodgepole pine, thus reducing contiguous host tree availability also makes for a more difficult environment for bark beetles, and reduces the ability of epidemics to develop. Similarly, decreasing the size of similar tree age and size patches of host trees will have the same effect as increasing species diversity, as younger age trees are not suitable host trees for most of the most prevalent tree killing bark beetle species. Finally, using harvest trees to trap beetles into, and then processing those trees thereby destroying the brood, combined with the use of synthesized aggregation and antiaggregation pheromones (attractants and repellents) to manipulate and control populations of beetles. All of these tactics have been used with documented success in western forests. They do require the skill and expertise of forest managers and forest entomologists, as well as a skilled and modern logging workforce. They also require a funding mechanism as the extensiveness of bark beetle mortality and risk is enormous (Figure 1). As a side note, we are quickly losing our skilled logging workforce in Montana (and across the West). Without this workforce and infrastructure to take these materials, we’ll lose our ability manage forests.
Another issue is what to do with the significant volume of already dead trees. In Germany much of the beetle infested or killed wood is harvested. Fifty percent of the more than four billion board-feet equivalent annual harvest in the German state of Bavaria, a forested land base of slightly more than 6 million acres, is salvage and sanitation harvest of dead and dying trees. This is all accomplished in a taxable profit generating free market system. What is suitable goes to sawmills and much of the rest is utilized for electricity, steam and home heating (Figure 2) with one third of all households heating with wood. Wood is rated as a renewable biomass source and replaces an equivalent of 396 million gallons of heating oil per year in Bavaria alone. Across the western United States, such utilization also occurs at a small scale in the form of rural home heating and cogeneration “hog-fuel” of some wood products industries. … One of the major barriers for such investments remains the availability of wood raw materials where 67 percent of the forested land base, bark beetles and all, is under federal management. …
Conserving tree species across their historical range with densities fitting the definition of “forest” both in the short term (next 50 years) and long term (next 50-200 years), that are capable of naturally regenerating and conserving their gene pool will be challenging if the predictions of climate change are realized. In addition, the characteristics and values associated with those forests have a greater probability of being conserved with active forest management than if left to what are deemed “natural” processes and consequences. “Active management” is defined here as the process where forests are inventoried within a reasonable scale for their biological and physical properties, that this knowledge is used to plan and implement landscape activities that provide for greater tree survival and natural regeneration when exposed to significant changes in temperature, precipitation and associated disturbances (wildfires, insects and diseases), and that all management options ranging from benign neglect to commercial tree harvesting are utilized. A thus managed forested landscape would consist of a mosaic of “wilderness” and “old-growth” patches as well as areas with harvests designed to promote tree vigor (thinning) and species and age class diversity (seed tree, shelterwood, patch cutting). In Montana, most Native American tribes have already adopted this management style on their reservation lands. Both the confederated Salish and Kootenai tribes (Flathead reservation) and Chippewa and Cree tribes (Rocky Boy reservation) are using active forest management as well as rapid salvage and sanitation harvesting to stem bark beetle epidemics and reduce the probability of catastrophic wildfire effects in their forests.
… As a forest practitioner with now 29 years of applied experience caring for trees and managing forests as well as extensive academic and scientific training and work on the ecology of Northern Rockies forest ecosystems, it is my opinion that active forest management and the use of wood-based renewable bioenergy applied in appropriate locations using both the academic and practical knowledge and experience currently available, will most likely result in greater forest resilience to large landscape level disturbances that are both within and outside of the historic range of variability. This will also maintain or increase most forest ecosystems ability to store and sequester atmospheric carbon dioxide.
