Economic Benefits from Violence Reduction Associated with Remediation of Abandoned Buildings and Vacant Lot Greening

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Abandoned buildings and vacant lots may create opportunities for violence by sheltering illegal activity and illegal firearms. A study by a Northern Research Station scientist and partners found blight remediation of abandoned buildings and vacant lots can be economically beneficial by reducing costs associated with firearm violence.

Blight remediation of abandoned buildings, such as the addition of new doors and windows; and greening of vacant lots related to storm water management and planting community gardens, can give urban areas a healthier sense of community. In turn, it makes these areas less appealing for criminal activity. Researchers analyzed the impacts and economic returns on investment of urban blight remediation programs involving 5,112 abandoned buildings and vacant lots as related to occurrences of firearm and non-firearm violence. Abandoned building remediation was associated with a 39 percent reduction in firearm violence. Relatedly, vacant lot greening was related to a 4.6 percent reduction in firearm violence. For every dollar spent on abandoned building remediation, taxpayers saved $5 through reduced firearm violence. Societal benefits of the same action resulted in $79 saved per dollar invested. For every dollar spent on vacant lot remediation, taxpayers and society benefited to the effect of $26 and $333, respectively. Urban blight remediation programs can be cost-beneficial strategies that significantly and sustainably reduce firearm violence.

Contacts

• Michelle Kondo, Research Social Scientist

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Predicting Pest Invasions

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During the last 150 years, hundreds of forest insects have accidentally been introduced to the United States, and many of these have caused substantial damage. The potential for new insect invasions remains as global trade continues to expand. Northern Research Station scientists and partners have developed a model incorporating sizes of source species pools and trade volumes to predict the numbers of new forest insect species likely to invade in the future.

Invasive insects have cost local government and homeowners millions of dollars and are a threat to forest health and productivity throughout the United States. Predicting how increasing rates of global trade will result in new establishments of potentially damaging invasive species is a question of critical importance to the development of national and international policies aimed at minimizing future invasions. Over time, successive introductions have actually depleted the number of potentially invasive species available overseas, however increases in imports have compensated for the effect of this depletion. Northern Research Station scientists developed a model that predicts future numbers of new species invasions based upon the abundance of species within invasion pathways. In this model the most abundant species are likely to invade first, while the many rare species are likely to invade only under high pathway (import) volumes. This mechanistic model is applied to make predictions of numbers of bark beetles likely to invade the U.S. from Europe over the next century but the model is widely applicable for predicting future invasions of all taxa and provides insights into how increases in rates of imports counteract the species pool depletion effect, resulting in the continued establishment of new species.

Contacts

• Andrew Liebhold, Research Entomologist

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Why Ice Storms Aren't Cool: Experimental Ice Storms Demonstrate Real Time Impacts on Northern Forests

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Station Director's Choice

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Extreme weather events are becoming increasingly common, creating dangerous disturbances to forests, towns, and cities. Scientists are pioneering new approaches to study these hazardous events with the long-term goals of making future forests and communities more resilient.

Ice storms are a common disturbance that can cause massive damage to north temperate and boreal forests worldwide. Because of the unpredictable nature of ice storms and difficulties in forecasting their occurrence, most past investigations of the ecological effects of ice storms have been based on case studies following major storms. During the winters of 2016 and 2017, scientists at the Hubbard Brook Experimental Forest in New Hampshire took a novel approach and created a suite of experimental ice storms in a northern hardwood forest. The icing treatments included targets of ¼, ½, and ¾ inch ice coating on tree branches sprayed in the winter 2016 to evaluate the impacts of different intensities of ice storms. In the winter of 2017, trees were sprayed with a ½ inch coating of ice to evaluate the impacts of consecutive ice storms. Early results show that the ice storm created gaps in the tree canopy and deposited large amounts of woody debris to the forest floor, but had surprisingly little impact on soil processes. The ultimate goal of this study is to provide information to stakeholders, such as utility companies, forest managers, and arborists, so that they will be better prepared to respond to big storms.

Contacts

• Lindsey Rustad, Team Leader / Research Ecologist
• John Campbell, Research Ecologist
Paul Schaberg, Research Plant Physiologist

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Increasing Atmospheric Carbon Dioxide Concentration Alters Forest Stand Development, so Do Management Guidelines Need Revision?

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A decade ago, increased atmospheric carbon dioxide was at the heart of the Aspen Free-Air CO2 Enrichment (Aspen FACE) experiment. Researchers in Rhinelander, Wisconsin, wanted to know if these increases affected forest growth. Their discoveries have implications for the validity of current forest management guidelines.

Building off of the Aspen Free-Air CO2 Enrichment (Aspen FACE) experiment in Wisconsin, Northern Research Station scientists are studying forests in northern Wisconsin to find out if forests may already have undergone developmental changes in response to increased carbon dioxide in the past century. Researchers grew pure and mixed stands of trembling aspen for 11 years in either present-day (360-380 parts per million) or elevated (560 parts per million) carbon dioxide and found compelling differences in stand development. Stands in elevated carbon dioxide grew faster and had developmental trajectories of self-thinning communities that carried more basal area at equivalent trees per acre. Comparison of the Aspen FACE stands to historical data suggests that current stocking guides underestimate maximum carrying capacity. In many situations, data used to develop currently employed stocking equations are in excess of 80 years old -- when atmospheric carbon dioxide was 33 percent less than today's 408 parts per million. Given that nearly every silvicultural practice is founded upon principles of stand development and size-density relationships, comprehensive reassessments may be needed because of atmospheric changes that have already occurred. To verify the experimental findings, field crews completed the first phase of surveys of pure and mixed trembling aspen stands on the Chequamegon-Nicolet National Forest. These assessments will be analyzed for their developmental characteristics for comparison to historical data.

Contacts

• Mark E. Kubiske, Research Plant Physiologist
• Christel Kern, Research Forester
• Christopher W. Woodall, Research Forester

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Investigating the Potential of CLT Panels made from Low-Grade Hardwoods for Building Construction

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Station Director's Choice

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The emergence of cross-laminated timber (CLT) for building construction in North America may provide an additional and valuable product market for low-grade hardwood logs.

Cross-laminated timber (CLT) is an engineered wood building material characterized by high strength and stability. Although scarce, existing research confirms that production of hardwood CLT is technically feasible. CLT made from low-grade hardwoods has the potential to become a building material that could be used as an alternative to concrete, masonry and steel. In a recent study, scientists randomly selected low-grade yellow-poplar (Liriodendron tulipifera) logs from two sites in the Central Appalachian region of the U.S. The logs were imaged using the U.S. Forest Service high-resolution laser scanner to measure and record surface defects and then sawn to maximize the production of timber for cross-laminated timber manufacture without respect to guidelines set out by the National Hardwood Lumber Association for grade. (Most common defects that reduce the value of the lumber are acceptable in CLT laminations.) By changing sawing parameters, scientists reduced the amount of wood residue and increased recovery. Overall yield of cross-laminated timbers from low-grade logs was 30 percent. Considering the low quality and low value of the material used, and potential value of the end product, these results are encouraging. Use of hardwood cross-laminated timber for building material is not well established yet. However, it has the potential to become a major application for low-value hardwoods from U.S. forests and generate economic opportunities in rural areas.

Contacts

• Ed Thomas, Research Computer Scientist

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Team Assesses Invasive Species Threat to Hawaii, Other U.S. Ports of Entry

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Introduced through pathways of international trade and tourism, invasive insects and pathogens can strike anywhere. Islands like Hawaii are especially vulnerable. A team of U.S. Forest Service scientists evaluated the risk of introducing nonnative pests that could endanger native Hawaiian plants. Lessons learned are applicable to other U.S. ports of entry.

The introduction of exotic insects and pathogens to the Hawaiian Islands could have devastating effects on native plants. Northern Research Station researchers collaborated with the Forest Service's Wood Import and Pest Risk Assessment Mitigation and Evaluation Team (WIPRAMET) to evaluate the risk of introducing nonnative pests that would endanger native Hawaiian plants. Pest Risk Assessments were developed by estimating the likelihood and consequences of the introduction of representative insects and pathogens of concern. Likely pathways of introduction were assessed. Twenty-four individual Pest Risk Assessments were prepared, 12 dealing with insects and 12 with pathogens. Six priority findings resulted from the analysis: 1) Inspection alone is not 100 percent effective in preventing introductions. 2) The primary sources of introductions are mainland United States and the Asia-Pacific region. 3) There is a strong need to make visitors aware that they are an important potential source of unwanted introductions. 4) Plant materials, especially live plants, are the most important source of pest problems for Hawaii. 5) The wood packing material pathway is insufficiently inspected and regulated. 6) The interstate movement of certain plant materials from Hawaii to the mainland is restricted, but similar restrictions on interstate movement to Hawaii are not. This analysis was used by the Hawaiian Department of Agriculture to develop a biosecurity plan. Many conclusions are also applicable to ports of entry on the mainland.

Contacts

• Jessie A. Glaeser, Research Plant Pathologist

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Putting Mountain Peatlands (and their Carbon Stocks) on the Map

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It is difficult to manage a resource when you do not know with certainty where to find it. Mountain peatlands are critically important ecosystems for storing water resources and organic carbon, yet they are poorly mapped. Northern Research Station scientists and partners improved methods for mountain peatland mapping, contributing toward high accuracy delineation of this important ecosystem across the globe.

Although covering only 3 percent of Earth's land surface, peatlands store about 30 percent of all soil carbon. Mountain peatlands are unique and important peatland types present in high elevation ecosystems across the globe, yet their distribution and reserves and fluxes of soil carbon are poorly understood. Working with colleagues at U.S. universities and scientists from tropical Andean countries of South America, Northern Research Station scientists are building scientific knowledge and capacity to manage mountain peatlands effectively. These peatlands are critical to water supply for major cities, are used as pasture for livestock, and are important reserves of carbon and sinks for atmospheric carbon dioxide, but are being impaired by changing land use. The research team has developed improved methods for mapping these peatlands' distribution, depth, and carbon stocks. Extensive peatlands in the Andes of Ecuador and Peru have been mapped. These peatlands, although lacking trees, store much more carbon per unit area than a typical tropical rainforest. The maps will be used as a basis for improved management of these ecosystems and to inform land use policy, and the methods developed will be useful in mapping peatlands in the mountains of the United States and across the globe.

Contacts

• Erik Lilleskov, Research Ecologist and Director's Representative

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Nonlethal Method of Defining White-nose Syndrome (WNS) Infection Proves Effective

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White-nose syndrome (WNS) has decimated hibernating bat populations in North America, but species in Europe appear to cope better with fungal skin infections that result in white-nose syndrome. A Northern Research Station scientist collaborated with scientists in the Czech Republic to develop a nonlethal method of comparing WNS infection in North American and European bats.

Perhaps the most catastrophic wildlife disease in a century, white-nose syndrome (WNS) has killed millions of bats in the United States, causing some species to be federally listed as threatened or endangered. Until recently, bats had to be dead or euthanized for laboratory testing procedures required to collect dermato-histopathological (skin lesion) samples from the wings, muzzle, and ears and to optimize detection of WNS. In addition, the severity scoring system for WNS currently in use requires the whole membrane from one wing. In order to conserve more individuals and recover affected species, finding a nonlethal sampling method was imperative. A Northern Research Station scientist and partners in the Czech Republic have validated a new nonlethal technique for identifying and targeting WNS skin lesions for sampling. Transillumination of a wing membrane with ultraviolet (UV) light elicits a distinct orange-yellow fluorescence that corresponds directly with the fungal cupping erosions in histological sections of the respective skin area. The fluorescence emitted from these skin lesions is associated with hyperaccumulation of riboflavin, a secondary fungal metabolite that may also represent a virulence factor leading to skin damage. When not being used in combination with infected wing membrane biopsies, UV transillumination can also be used for noninvasive photographic surveillance of infection intensity. The proposed semi-quantitative pathology score was tested and proved to be a powerful and widely applicable tool for defining WNS severity.

Contacts

• Sybill Amelon, Research Wildlife Biologist

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Implementation of Science-based Trials of Rowcrops Integrated with Prairie Strips (STRIPS): Incorporating Ecosystem Services into Midwest Agriculture

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Station Director's Choice

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Science-based Trials of Rowcrops Integrated with Prairie Strips (STRIPS) is transforming the way we conduct agriculture in the Midwest. STRIPS strategically integrates native prairie strips into rowcrop agriculture to achieve a greater number of benefits, including reduced soil erosion and better habitat for birds, pollinators, and other insects.

Prairie strips also enhance habitat for biodiversity, including birds, pollinators and other beneficial insects, reducing the need for pesticides. A partnership led by Iowa State University, the Leopold Center, the U.S. Fish and Wildlife Service and the Forest Service's Northern Research Station has resulted in many presentations to farmers, stakeholders, farm-related agencies and agri-businesses; 26 peer-reviewed publications (including a paper in Proceedings of the National Academy of Sciences (PNAS)): numerous popular articles including the New York Times and the Washington Post; and a handbook highlighting the benefits and methods of integrating strips into row crops. Researchers recently implemented STRIPS 2, which is placing prairie strips in actively managed row crop systems across Iowa. Currently more than 30 actively managed farms have implemented STRIPS with that number growing daily. Wide use of STRIPS has the potential to decrease nutrient inputs to the Gulf of Mexico and reduce the hypoxia zone.

Contacts

• Randy Kolka, Team Leader / Research Soil Scientist

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Children's Connections to Nature Prove to be Lasting

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Childhood nature experiences have lifelong positive effects. Children's voluntary engagement with nature - as opposed to exposure through schools and other organized programs - is an effective exposure mechanism for creating lasting effects, suggesting the importance of giving children opportunities to experience nature in ways that have less structure and more opportunities for free play.

Nature experiences have many long-term benefits to children and adults, including improving several aspects of human health, fostering the development of personal and social capabilities, improved test scores, self-discipline, and reduced behavioral problems. This study examined different mechanisms through which children and youth are exposed to nature and the extent to which different exposure mechanisms are associated with long-term benefits. Four mechanisms of exposing children to nature were examined: voluntary engagement (on one's own and with friends); with family; through school-related programs; and through extracurricular organized programs such as churches and Scout groups. Scientists assessed the effect of each of these exposure mechanisms on adult environmental citizenship and adult attitudinal and behavioral commitment to nature-based activities. Children?s voluntary engagement with nature emerged as the strongest predictor of a number of aspects of adulthood environmental citizenship and of behavioral and attitudinal commitments to nature-based activities. This suggests the importance of exposing children to nature in ways that have less structure and more opportunities for free play and free-choice learning. But exposure to nature through family activities significantly predicts adults' tendency to continue to participate in nature-based activities, suggesting the need for multiple exposure pathways to achieve the many benefits of childhood exposure to nature.

Contacts

• David N. Bengston, Research Forester
• Lynne M. Westphal, Project Leader / Research Social Scientist

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SLow Ash Mortaltiy (SLAM) Approach Reduces Emerald Ash Borer Numbers

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Emerald ash borer (EAB), the most destructive forest insect pest that has ever invaded North America, has killed hundreds of millions of ash trees, resulting in enormous economic and ecological damage. Scientists are testing methods for detecting and killing EAB to help forest and land managers prevent its spread.

Tools and guidelines are needed for early detection and management of the invasive emerald ash borer (EAB), which has killed hundreds of millions of ash trees since its discovery in North America in 2002. Scientists tested the use of girdled ash trees for EAB detection and as trap trees or "sinks" to attract beetles and then kill them or destroy infested trees. Low-density EAB infestations were readily detected with girdled ash trees. Injecting trees with systemic insecticide a few weeks prior to girdling produced lethal trap trees that attracted and killed EAB and reduced larval densities. A large multi-agency pilot study was conducted to test the SLow Ash Mortaltiy (SLAM) integrated strategy for managing EAB using a combination of tactics including girdled ash trees, regulatory control, public outreach, ash tree removal, and insecticide treatments. While a very small proportion of ash trees in the ~150 square mile project area were treated with insecticide or girdled, both tactics reduced EAB densities and protected ash trees in areas surrounding the treatments. Model results indicated that EAB spread rates were reduced from areas with girdled trees. Trees treated with the systemic insecticide also reduced larval abundance in subsequent years. These results will lead to improved area-wide management strategies and development of guidelines for forest managers and decisionmakers to control EAB and protect the ash resource.

Contacts

• Therese M. Poland, Project Leader and Research Entomologist

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Adapting Urban Forests to a Changing Climate

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A framework for urban forest vulnerability assessment and adaptation, piloted with partners in the Chicago region, is informing master planning for urban trees in the city of Chicago and is expanding to other urban areas in the Midwest and Northeast.

Urban forests improve the lives of people in cities, including reducing the urban heat island effect, controlling stormwater, and improving air quality. Maintaining and building strong urban forests is thus a key way for cities to adapt to warmer temperatures and changing precipitation patterns. But urban trees themselves may be threatened by intense heat, severe storms, rising sea levels, and more pests and diseases. Scientists at the Northern Research Station and the Northern Institute of Applied Climate Science developed a framework for urban forest adaptation. This framework was piloted in the Chicago region in collaboration with the Chicago Region Trees Initiative and other partners. A vulnerability assessment revealed that roughly 20 percent of the region's trees were vulnerable to climate change, and many of the trees that were not vulnerable were nonnative invasive species. Workshops with municipal foresters, parks department managers, and forest preserve managers integrated this information into local, on-the-ground projects. Information is now being incorporated into the Chicago Region Trees Initiative Master Plan. Lessons learned from the Chicago pilot have been applied to other urban areas in the Midwest and Northeast. Workshops in the Twin Cities, Boston, and Philadelphia brought together more than 150 urban forestry professionals to understand local impacts of climate change and develop their own local adaptation strategies. These efforts have resulted in real-world demonstrations of how people are adapting their urban forests to climate change.

Contacts

• Leslie Brandt, Climate Change Specialist
• Chris Swanston, Research Ecologist

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El Niño and El Niño Modoki Impacts on Extreme Precipitation in the U.S.

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Many areas of the United States are vulnerable to socioeconomic disruptions caused by extreme precipitation and resulting floods. Northern Research Station science is helping identify the different extreme precipitation occurrence patterns resulting from episodes of eastern Pacific Ocean warming (El Niño) and central Pacific Ocean warming (El Niño Modoki).

Intense precipitation events lasting from 1-24 hours can lead to major flooding with serious social, economic, and environmental impacts. Many factors affect the development of weather patterns conducive to extreme precipitation in the U.S., including changes to the climate system brought on by warming of the eastern or central Pacific Ocean waters, known as El Niño and El Niño Modoki, respectively. Forest Service researchers worked with colleagues at Michigan State University to investigate the similarities and differences in the patterns of warm-season (May-October) and cold-season (November-April) sub-daily extreme precipitation occurrences across the U.S. during El Niño and El Niño Modoki episodes that occurred over the 1979-2013 period. Results from the study suggest there are significant regional differences in the occurrences of extreme precipitation in the U.S. during El Niño and El Niño Modoki episodes, with cold-season extreme precipitation occurrences being more strongly associated with El Niño than El Niño Modoki episodes. Understanding when and where extreme precipitation and associated flooding could occur in the U.S. in response to El Niño or El Niño Modoki episodes can aid in the development of emergency management and environmental plans for responding to and mitigating the effects of damaging floods.

Contacts

• Warren E. Heilman, Research Meteorologist
• Xindi (Randy) Bian, Meteorologist

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NRS Scientists Disentangle Some of the Complexity Associated With Wildland Fires

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Station Director's Choice

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Planned wildland fires are conducted with the goals of reducing hazardous fuels and the severity of future wildfires, and creating desired conditions of forest structure and composition. How do fire managers optimize desired outcomes while reducing the impacts of smoke emissions and ember transport?

U.S. Forest Service, Northern Research Station scientists and collaborators are exploring the complex interactions between fire behavior, fuel loading and consumption, and turbulence and smoke dispersion during wildland fires of varying intensities in the New Jersey Pinelands. Measurements in wildland fires ranging from low-intensity backing fires to high-intensity crowning fires have shown that turbulence and heat flux are strongly linked to fire intensity, but the consumption of fuels on the forest floor and understory are only weakly related to the increased turbulence, dispersion of smoke, and ember production associated with higher intensity fires. Instead, consumption of fuels on the forest floor is strongly related to initial fuel amounts. This means that low-intensity fires can be effective at consuming surface fuels without causing some of the undesirable effects of high-intensity fires. Results from this research have led to the development and evaluation of an advanced smoke emission model that incorporates the effects of the forest canopy on wind and dispersion of smoke during low-intensity prescribed fires, and a better understanding of turbulence and heating in the fire environment. Research efforts are also resulting in unique field data sets to test a new, physics-based fire behavior model developed by USDA Forest Service researchers, the Wildland Urban Interface Fire Dynamics Simulator (WFDS).

Contacts

• Ken Clark, Research Forester

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Forest Service Moves American Elm a Big Step Closer to Landscape Restoration

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Over the past several decades, mature American elm trees have virtually disappeared from city streets and eastern forests as a result of Dutch elm disease (DED). Northern Research Station scientists are on the cusp of developing sufficient genotypes to successfully restore new selections of American elm back to the landscape. Dutch elm disease inoculation trials initiated in Ohio in June 2016 have yielded American elm cultivars that exhibit low levels of DED-induced decline 1 year later.

Prior to the outbreak of Dutch elm disease (DED) fungal pathogens, American elm trees were widely dispersed across the eastern United States, thriving in a variety of different forest habitats. Over the last several decades, considerable progress has been made cultivating new genotypes of American elm trees that are tolerant to DED. Yet, from an operational standpoint the existing DED-tolerant cultivars lack the genetic diversity necessary for large-scale landscape restoration and are not regionally adapted. In June 2016, more than 850 American elm trees were inoculated with DED to assess tolerance levels. The American elm material was derived from crosses between DED-tolerant individuals as well as material from large survivor trees. DED-induced canopy decline was assessed at 8 weeks and 1 year after inoculation. At 1 year post-inoculation, 18 selections have exhibited tolerance (less than 20 percent DED symptoms) to the disease. These varieties will continue to be assessed for tolerance and will be incorporated into restoration plantings across the urban to rural gradient.

Contacts

• Jim Slavicek, Project Leader / Research Biologist
• Charles Flower, Research Ecologist
• Cornelia Pinchot, Research Ecologist

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Land Use Conversion to and from Forest Land has Important Implications on the National Greenhouse Gas Budget

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Land use and land use change data from the Forest Inventory and Analysis program facilitates a first-of-its-kind analysis of carbon dynamics associated with forest land conversion in the National Inventory Report of Greenhouse Gas Emissions and Sinks in the United States.

As signatories to the United Nations Framework Convention on Climate Change, the United States submits a National Inventory Report of greenhouse gas (GHG) emissions and sinks each year, which includes GHG estimates from forest land contributed by the Forest Service and compiled by the Northern Research Station's Forest Inventory and Analysis Program. In 2015, the forest land category represented an estimated offset of 11.8 percent of economy-wide GHG emissions. Since 1990, forest land area has increased by an estimated 0.15 percent per year (390,000 ha) or about 10 million ha total through 2015. These increases are due, in large part, to the conversion of abandoned croplands to forest land and reversion and expansion of trees in grassland ecosystems. There have also been losses in forest land over the past 25 years, predominately to grasslands, croplands, and settlements. The estimated net U.S. carbon flux associated with forest land conversion over the last decade is approximately zero, with gains in forest land constituting sequestration of 23 teragrams of carbon of per year and losses resulting in emissions of 23 teragrams of carbon per year. The estimated emissions constitute decades and possibly centuries of accumulated carbon within these forests, which is abruptly or gradually released to the atmosphere during land use conversion, whereas the gains in forest land only represent carbon sequestration from new growth of live biomass and the accumulation of newly dead organic matter over the 20 years since land use conversion.

Contacts

• Grant M. Domke, Research Forester

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Managing the Foodscape to Alleviate Deer Browsing

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Forest plant biodiversity is being degraded by browsing from overabundant deer herds, but forest management can alleviate impacts. Research by Northern Research Station scientists and partners has expanded understanding of how forage availability throughout the landscape, or the "foodscape," influences browsing to provide guidelines forest managers can use to reduce browse impacts.

Browsing by deer can degrade forest diversity, impede sustainable management, and threaten forest health across millions of acres of public and private forests in the United States. Although managing browse impacts is daunting, deer behavior, including browsing, is shaped by the risks and rewards deer experience throughout their home range, including the quantity and quality of forage. Northern Research Station scientists and partners are improving understanding of how forage availability throughout the landscape, or the "foodscape," influences browsing and are developing guidelines managers can use to reduce browse impacts. Researchers measured browse impact to plant diversity in 23 forests in Pennsylvania. For each area, they characterized the foodscape in the surrounding square mile focusing on the abundance of forage-rich and forage-poor habitats. The study found strong signals that foodscapes altered browsing. Specifically, in foodscapes with abundant forage-rich, early-successional habitat, often created by forestry, browse impact waned and ultimately disappeared. Conversely, in forage-poor foodscapes browse impact intensified. Our results are significant to a region where deer browsing can depreciate stand values by approximately $1100/acre and degrade habitat quality for other values, including wildlife and recreation. These findings reveal that by improving foodscapes, forestry can provide complementary benefits to wildlife, biodiversity, and sustainable management.

Contacts

• Alejandro Royo, Research Ecologist

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A Native Fungus Takes on an Exotic and Aggressive Tree Species

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Working with the Wayne National Forest and the Ohio Department of Natural Resources, scientists from the Northern Research Station are studying a native fungus and finding that it kills ailanthus while sparing native tree species. Inoculations in research trials began in 2015 in Ohio and appear to be successful.

Ailanthus, commonly known as tree-of-heaven but more appropriately called "stink tree" due to the pungent order of its crushed foliage, is an introduced invasive common in eastern mixed oak forests. Since it is a rapidly growing and prolific tree, it often displaces native plants and disrupts forested ecosystems. It is very challenging to control chemically because it is a prolific sprouter. However, there may be an alternative biocontrol in the near future. A native soil-borne fungus, Verticillium nonalfalfae, which was discovered in Pennsylvania by Penn State researchers, is very specific and deadly to ailanthus but not to more than 75 other woody species. In a trial on the Wayne National Forest in Ohio, three Ohio state forests and a private, non-profit wildlife conservation center, researchers are testing the effectiveness of the fungus in killing ailanthus as well as monitoring subsequent regeneration. To date, control has been effective with no off-target effects being observed. Northern Research Station scientists are continuing to formally study nontarget effects before large-scale releases into forest environments begin. Scientists are also investigating ways to streamline the production of inoculum by developing improved and expedient culturing methods of fungal spores; existing production methods take 3 to 4 weeks to complete and are labor intensive.

Contacts

• Joanne Rebbeck, Plant Physiologist

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New Tool Detects Oak Wilt Fungus Faster and More Accurately

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Oak wilt is one of several significant oak diseases threatening oak health in the United States and is a potential threat worldwide. Accurate and timely laboratory diagnosis is critical to controlling the disease. A Northern Research Station scientist and collaborator have developed and validated two molecular-based diagnostic tools that greatly exceed standard isolation methods in time required and accuracy.

Caused by the fungus Ceratocystis fagacearum, oak wilt is causing crown wilt and death of oaks in 24 U.S. states; it has been particularly destructive in the Upper Midwest and Texas. If left unmanaged, the disease can dramatically alter urban and natural ecosystems. Effective disease management relies on accurate and timely diagnosis of the disease. Working with a University of Minnesota graduate student, a Northern Research Station scientist has modified molecular protocols for effective and routine use by plant disease diagnostic laboratories. Fungal DNA was extracted from drill shavings taken from the sapwood of red, bur, and white oaks in different stages of oak wilt development. Amplification of the DNA was completed using either nested or real-time polymerase chain reaction methods. Resulting levels of pathogen detection were compared with rates of detection using standard isolation methods. The molecular protocols were superior in detection frequencies compared to isolation for samples from actively wilting bur and white oak trees. The pathogen could only be detected in 1-year-old dead branches (bur, white) and main stems (red) of oak species using the new techniques. The molecular assays can be conducted in fewer than 2 days compared to 10 to 14 days incubation required for isolation. University and state agency diagnostic laboratories are using the methods, particularly for problematic samples.

Contacts

• Jennifer Juzwik, Research Plant Pathologist

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In the Aftermath of the Emerald Ash Borer Invasion: Forest Recovery and Management Using Biocontrol

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The invasion of forests by the emerald ash borer (EAB) has resulted in the death of hundreds of millions of ash trees throughout much of the U.S. Researchers are studying how effective biocontrol methods are in managing EAB populations in Michigan forests.

Emerald ash borer (EAB), a pest of ash trees native to Asia, was introduced to North America in wood-packing materials used in international trade during the 1990s. This beetle was discovered in Michigan in 2002, and to date infestations have been found in 31 states. EAB is now considered the most destructive nonnative insect to invade North American forests. In 2007, after three insect species that attack EAB in Asia were approved for release in the U.S., the U.S. Department of Agriculture started the EAB biocontrol program. At study sites in Michigan where these EAB biocontrol agents from Asia were first released, researchers continue to monitor the prevalence of introduced and native natural enemies, and their effects on EAB populations, ash tree health, and ultimately forest recovery. During the last 10 years, the sustained establishment and spread of two EAB biocontrol agents released in Michigan has been confirmed. Recent tree inventories at the study sites revealed large numbers of ash saplings and young trees, and the health of this surviving ash correlated with a biocontrol agent that attacks EAB feeding in small diameter ash trees. These findings indicate that EAB biocontrol may improve the outlook for ash trees in North American forests in the aftermath of EAB.

Contacts

• Leah Bauer, Research Entomologist

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Providing Comprehensive Information about Road BMP Effectiveness Helps Protect Water Quality on Forest Lands

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Station Director's Choice

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Sediment is the most common pollutant associated with forests, and roads are the most common sources of sediment in forests. Northern Research Station scientists compiled a synthesis summarizing the effectiveness of best management practices (BMPs) designed to control erosion from roads and protect receiving water quality.

Roads are integral to forest use and forest management. They provide access for a myriad of uses, including recreation, wildlife management, timber management, minerals extraction, and many other activities. However, because of their design, they restrict water infiltration, concentrate overland runoff, and intercept subsurface drainage. All of these factors contribute to increasing runoff, erosion, and sediment transport, with the ultimate result commonly being negative impacts to water quality and aquatic health from elevated inputs of sediment into receiving surface waters. Best management practices (BMPs) are tools and techniques that reduce erosion and sediment transport. Since roads are the most common sources of sediment in forests, most forestry BMPs are implemented on forest roads. Across the nation, there are dozens of types of BMPs and hundreds of ways those BMPs are applied, but little information had been compiled for land owners and land managers to summarize and compare the effectiveness of similar BMPs or BMPs with the same intended outcome. Northern Research Station researchers have compiled and published what is probably the comprehensive synthesis of the literature ever written on the effectiveness of forest road BMPs. National Forest resource specialists and engineers are among the major users of the literature synthesis, particularly during planning and resource impact analysis in the NEPA process.

Contacts

• Pamela Edwards, Research Hydrologist

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What Are the Potential Implications of Expanding Woody Biomass Harvesting to Forest Biodiversity?

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The U.S. Department of Energy;s 2016 Billion-Ton Report, Volume 1, identified a vast national potential of biomass resources that could be available for industrial uses in the future, but what are the potential environmental implications to our forests with an expanded forest biomass production program?

Understanding the effects of an expanded forest biomass production program requires specifics on how much is available, where is it located, and how much biomass can be produced and used most effectively. Determining where expanded biomass production may occur aids in evaluating environmental benefits and consequences spatially and, ultimately, evaluating the sustainability of expanded biomass production. A Northern Research Station scientist collaborated with Weyerhaeuser and the National Council for Air and Stream Improvement, Inc., to evaluate the implications of expanding wood biomass harvesting for forest biodiversity using projected available forest feedstocks generated in the Billion-Ton Report. Removing wood biomass is expected to affect biodiversity through the loss of dead and downed material associated with harvesting logging residues, and greater canopy cover and altered age distribution associated with biomass whole-tree harvesting. Results show nearly half of projected harvests occurred in southern U.S. followed by north-central and northeast regions, and the primary feedstock producing biomass was logging residues. As expected, the forest type producing primary feedstocks varied across the country. Analysis showed that depending on their distribution and habitat requirements in relation to predicted location and type of biomass harvested, species that rely on wood biomass or early successional habitat could experience both negative and positive impacts. Spatial results can be integrated with local biodiversity assessments to help identify species vulnerable to increased woody biomass harvesting.

Contacts

• Deahn Donner, Project Leader / Research Ecologist

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Managing for Hardwood—Softwood Mixtures as a Path to Economic and Ecologic Resiliency

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Forests composed of a mixture of hardwood and softwood trees offer a variety of potential ecological and economic values beyond what pure stands provide. Scientists are exploring the benefits and the challenges of managing these forests.

Maintaining healthy and diverse forests is essential for providing clean water, habitat, and wood products for sustaining robust rural economies. Mixed hardwood-softwood stands, or "mixedwoods", are structurally and compositionally diverse because of the differing shade tolerances, growth rates, longevities, and crown and root structures of the constituent species. This structural and compositional diversity results in greater habitat diversity, a more flexible and diverse forest product stream, and forests that potentially are more resistant or resilient to pests and pathogens, as well as environmental stressors such as drought and fire compared to pure stands. Scientists from the USDA Forest Service, Northern Research Station, are leading an effort with other scientists from universities and agencies in the U.S. and Canada to critically examine the economic and ecologic benefits of mixedwood forests and to address challenges associated with their management. Outreach to managers across multiple forest types is providing a new paradigm in which mixedwoods are recognized as distinct forest types with greater resiliency and more robust economic prospects for the changing global forest economy. Although regenerating and recruiting the softwood component of mixtures remains challenging, mixedwood types are more resistant to insect pests and may be more resilient to other environmental stressors.

Contacts

• John Kabrick, Research Forester
• Daniel C. Dey, Research Forester
• Ken Clark, Research Forester
• Laura Kenefic, Research Forester
• Christel Kern, Research Forester

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Mountain Pine Beetle: A Real Threat to Pines of Eastern North America

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The mountain pine beetle is spreading east through the Canadian boreal forest. Northern Research Station science suggests that the insect will find suitable hosts and survive cold winters in eastern North America, making it a serious threat to the region.

Mountain pine beetle is a devastating forest insect in western North America, where it has killed millions of pines. Changing winter temperatures have allowed the insect to escape geoclimatic barriers to its historic distribution, and it is spreading east through a contiguous band of Canadian jack pine that leads to the northeastern United States. Northern Research Station scientists and partners evaluated the potential suitability of pines common to eastern North America for the insect. Bolts of eastern white, red, and Scots pine were cut from Minnesota and taken to the Black Hills National Forest in South Dakota, where the mountain pine beetle is a native species. Uninfested lodgepole and ponderosa pine, known hosts for the insect, were cut from Wyoming and South Dakota as positive controls. Several studies were conducted to determine whether the beetles would recognize the cut bolts as hosts, would reproduce in these species, and would be able to overwinter. All pine species were attractive to mountain pine beetles, were readily colonized, and supported reproduction and development. Host species affected the cold hardiness of overwintering individuals. This research highlights the threat that mountain pine beetle pose to pines of eastern North America.

Contacts

• Robert C. Venette, Research Biologist

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