SOS Forests

Active Forest Management Is the Solution to Bark Beetles

Dr. Peter Kolb, 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, testified last month before the House Natural Resources Subcommittee on Water and Power Hearing on Mountain Pine Beetle: Strategies For Protecting The West.

His testimony is now posted in the W.I.S.E. Colloquium: Forest and Fire Sciences [here].

It is a very interesting and powerful testimony. Dr. Kolb correctly described bark beetles 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.

He further described bark beetle ecology and some of the factors that lead to large outbreaks, including mild winters, long summers, and forest conditions that provide ample susceptible trees.

Dr. Kolb also reported on German forests, and the successes and failures in dealing with insect infestations there.

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. …

To emphasize a point, Germany is the size of Montana yet harvests as much volume annually as the US Forest Service harvested annually nationwide at the height of federal timber harvest in the 1980’s. The current harvest from USFS lands is 1/6th of that. (For more discussion and charts regarding the declining federal harvest, see National Forest Timber Management: Myth, reality, and some questions for the future by W.V. (Mac) McConnell [here]).

German foresters have avoided insect infestations through silvicultural practices that have also retained and enhanced other forest values. From Dr. Kolb’s testimony:

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. …

There is a lesson here. We could also avoid bark beetle infestations, such as the one that has recently killed vast tracts of forests across Colorado and Wyoming. From Dr. Kolb:

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.

… 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.

… 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.

An excellent testimony. Kudos to Peter Kolb. Let’s hope Congress absorbed the lesson.