Research Highlights - Sustaining Forests
The Northeastern and Midwestern forests are the defining elements of much of the natural environment in their region. This region is the most heavily forested region of the United States, and 76 percent of the forested lands are privately owned, mostly by non-industrial, family landowners. Sustaining this mix of privately owned and public forests involves understanding their ecology (at scales ranging from individual organisms to broad landscapes); their relationships to people and communities; and developing appropriate management strategies in the face of changing environmental conditions (climate) and of changing social conditions (economics and demographics).
2012 Research Highlights
Is a Once Mighty Tree Species Ready for a Comeback?
American chestnut was the dominant tree species in the Appalachian Mountains before an introduced fungus almost extirpated it and changed the way of life for early inhabitants who relied on this tree for food, shelter, and animal production. Helping the American chestnut tree move toward a comeback, the Northern Research Station's Hardwood Tree Improvement and Regeneration Center (HTIRC) and The American Chestnut Foundation (TACF) have begun two restoration plantings on the Wayne and Hoosier National Forests. HTIRC staff from both NRS and Purdue University and the Indiana Chapter of TACF helped coordinate and plant the initial restoration sites in the Midwest. These plantings are an important next step to test blight resistance in the field and to understand the ecological steps necessary for successful restoration of American chestnut.
National Forest System: Wayne and Hoosier National Forests; Indiana State Nursery; Purdue University; The American Chestnut Foundation, Indiana Chapter
Harvest Gaps to Restore Tree Diversity in Managed Forests
A medium-size (20-m-diameter) gap has been accepted in practice as the "perfect" gap size to restore or maintain tree diversity in northern hardwood forests. However, when tree regeneration in harvest gaps of various sizes was examined for over a decade in northern hardwoods, the results were surprising. Less abundant tree species were found to grow better in larger gaps (up to 46 m in diameter) but survive better in small gaps (6- to 10-m-diameter), suggesting that medium gaps may provide an acceptable tradeoff between growth and survival. However, the density of these species was low, regardless of gap size, suggesting that the role of gap size in tree diversity may be dampened by other site factors such as deer browsing and shrub competition. This work challenges conventional wisdom about the perfect gap size and provides empirical evidence to guide management decisions on responses of trees to gap size. Results from this research are already influencing forest management practice and planning on public lands in Minnesota and Wisconsin.
National Forest System: Chequamegon-Nicolet National Forest; University of Minnesota
Effects of Disturbance, Climate, and Management on U.S. Forest Carbon
Recent climate variability (increasing temperature and droughts) and atmospheric composition changes (nitrogen deposition, rising carbon dioxide concentration), along with harvesting, wildfires, and insect infestations, have had significant effects on U.S. forest carbon uptake. The carbon changes in forests of the conterminous U.S. can be attributed to disturbance and non-disturbance factors. Scientists from the Northern Research Station combined an advanced ecosystem process model with data from Forest Inventory and Analysis and remote sensing to separate the effects of disturbance factors (harvesting, fire, and insects) from non-disturbance factors (climate variability, carbon dioxide fertilization, and nitrogen deposition). Results showed that disturbance factors had the strongest effects overall, but with significant regional and temporal differences. This is the first time such separation of causes has been possible at the continental scale. This new information can be used to support development of policies and approaches to improve sustainable forest management and provide for cleaner air and water.
University of Toronto; Nanjing University, China
New Management Strategies for Northern White-Cedar
Northern white-cedar (Thuja occidentalis L.) is one of the least studied commercially important species in the northeastern U.S. and Canada. White-cedar is valued as a source of niche products such as shingles and fence posts and as a sacred plant for Native Americans; it contributes to biodiversity by increasing local tree species richness and providing wildlife habitat. But foresters have little and often contradictory information about cedar ecology and silviculture. In response to this information need, Northern Research Station scientists and their partners conducted more than a decade of research, resulting in new silvicultural guidelines for white-cedar in the variety of habitat types where it is found. Their work includes a synthesis of knowledge as well as new studies of white-cedar regeneration, growth, mortality, site relationships, and responses to treatment. Their recommendations include retaining and releasing cedar in managed stands, and establishing and protecting advance regeneration and residual trees during harvesting. A new management guide, jointly published by the U.S. Forest Service and the Canadian Forest Service in English and French, has been produced.
Morrisville State College, New York; Northeastern States Research Cooperative; University of Maine, School of Forest Resources; Centre d'enseignement et de recherché en foresterie de Sainte-Foy, Inc., Ministere des Ressources naturelles et de la Faune du Quebec; Natural Resources Canada; Canadian Wood Fibre Centre; Nova Sylva Inc.; Universite Laval, Quebec, Canada; Southern Sciences and Information Section, Ontario, Canada
2011 Research Highlights
Long-Term Differences in Forests With Different Deer Densities
Thirty years after a study on the effects of deer on forest ecosystems established new forest stands at deer densities ranging from 10 to 64 deer per square mile, Forest Service scientists found that tree species diversity, canopy foliage density, insect density and bird density, all decreased significantly as the deer density at stand initiation increased. If deer densities were high initially, the effects carried over, even if densities were lower later.
In a large-scale, 30-year controlled experiment, Forest Service scientists found that 10 years of different densities of white-tailed deer created contrasting forest tree communities with effects that ricocheted up the food chain even 20 to30 years later. Higher deer densities during stand initiation resulted in significantly reduced diversity of tree species, and density of canopy foliage, canopy insects, and birds, even thirty years later. Because recruitment of trees from seedlings to the canopy occurs over a relatively brief, early period (for about 10 years) these results show that even short-term variations in deer density may cause centuries-long disruptions to forest ecosystem structure and function. As numbers of predators decline and herbivores increase worldwide, similar effects may persist long after herbivore density becomes effectively managed.
Forest Service partners: National Forest System, Allegheny National Forest
External partners: Timothy Nuttle and Ellen Yerger, Indiana University of Pennsylvania; Pennsylvania Department of Conservation and Natural Resources, Bureau of Forestry and Pennsylvania Game Commission; Seneca Resources
Nuttle, T.; Yerger, E.H.; Stoleson, S.H.; Ristau, T.E. 2011. Legacy of top-down herbivore pressure ricochets back up multiple trophic levels in forest canopies over 30 years. Ecosphere 2(1):4.
Horsley, S.B.; Stout, S.L.; deCalesta, D.S. 2003. White-tailed deer impact on the vegetation dynamics of a northern hardwood forest. Ecological Applications 13(1): 96-118.
Housing Trends and Impacts on the Secondary Wood Industry
Forest Service researchers analyzed the current housing market through the perspectives of subscribers to a major U.S. trade publication with more than 33,000 subscribers in the secondary woodworking industry. These subscribers---manufacturers of cabinets, flooring, architectural fixtures, and related products--- are critical users of lumber from the nation’s hardwood forests. This analysis provides small manufacturers with information to better understand their current economic and competitive environment and with ideas for surviving the housing downturn.
Forest Service scientists, working in collaboration with Virginia Tech and Wood & Wood Products magazine, analyzed the current housing market through the perspectives of the magazine’s 33,000 subscribers. This analysis was requested as a follow-up to a successful study with the same cooperators in 2010. An article based on the 2010 study, for example, was among the “top 5 most-viewed articles” for the entire year on Wood & Wood Products’ website, illustrating the importance of this research to wood manufacturers. In the 2011 study, the scientists developed a series of questions to measure the impacts of the housing downturn on the wood products industry and to determine what actions were being taken to remain profitable. The survey was then presented by the magazine’s staff to their subscribers. The results help manufacturers (especially smaller firms) better understand current economic conditions and tactics within their industry and are invaluable to researchers as a barometer of industry activity and perceptions. The results were published in the July 2011 edition of Wood & Wood Products as a cover featureand posted on the magazine’s website.
Urs Buehlmann, Virginia Tech; Karen Koenig, Wood & Wood Products magazine
Buehlmann, U.; Bumgardner, M.; Schuler, A.; Koenig, K. 2011. Housing and the wood industry: trends and market conditions. Wood & Wood Products July:24-29.
Impediments to Woody Biomass Utilization on Federal Lands
Although increasing utilization of woody biomass from federal lands is seen as a key part of facilitating fuels treatments on federal lands, efforts to increase utilization have met with limited success. Forest Service researchers studying the social dynamics of biomass use on ten sites on federal lands therefore paid particular attention to assessing the reality of persistent conventional wisdoms about what limits utilization.
Because “accepted truths” are not necessarily accurate, they can negatively influence the framing of problems and actions. The researchers found that the conventional wisdoms were reasonably accurate, although the degree to which each impeded progress varied.
Dennis R. Becker, University of Minnesota; Kathleen E. Halvorsen, Michigan Technical University; Cassandra Moseley, University of Oregon
Becker, D.S.; McCaffrey, S.; Abbas, D.; Halvorsen, K.; Jakes, P.; Moseley. C. 2011. Conventional wisdoms of woody biomass utilization on federal public lands. Journal of Forestry, 109(4):208-218.
Recovery of Paper Birch From Crown Injury Is Linked to Soil Calcium
Acid rain leaches calcium from forest soil and may indirectly slow recovery of tree growth and condition after storm injury
Greater dieback and growth reductions of paper birch growing on low-calcium soils following the 1998 ice storm suggests an additional impact of acid rain-induced calcium depletion.
The regional ice storm of 1998 damaged the crowns of many hardwood trees, including paper birch. Subsequent crown dieback and mortality of paper birch has been reported throughout New York and New England. A Forest Service scientist and collaborators evaluated the timing and nature of decline in Vermont and found that birch experienced dramatic reductions in woody growth following the 1998 ice storm. However, trees on calcium-rich soils rebounded in growth after initial declines, whereas trees on calcium-poor soils experienced continued low growth and crown deterioration. This phenomenon has been previously documented for red spruce and sugar maple in the region, highlighting the importance of calcium---a nutrient vulnerable to leaching loss from acid rain---for tree recovery from environmental stress.
Forest Service partners: National Forest System, Green Mountain National Forest
External partners: Joshua M. Halman, Gary J. Hawley, and Christopher F. Hansen, University of Vermont; Vermont Department of Forests, Parks, and Recreation
Halman, Joshua M.; Schaberg, Paul G.; Hawley, Gary J.; Hansen, Christopher F. 2011. Potential role of soil calcium in recovery of paper birch following ice storm injury in Vermont, USA. Forest Ecology and Management. 261: 1539-1545.
2010 Research Highlights
Second edition published of The Ecology and Silviculture of Oaks
The second edition of The Ecology and Silviculture of Oaks was recently authored by retired NRS scientist Paul Johnson (Columbia, MO) and NRS scientist Stephen Shifley), with their colleague Robert Rogers (University of Wisconsin--Stevens Point, Emeritus). With 580 pages and more than 200 figures, the second edition includes much new material on artificial regeneration, effects of climate change, managing for biomass and carbon sequestration, oak decline, and sudden oak death as well as the material covered in the 10 chapters of the first edition.
This book presents a holistic approach to oak ecology and silviculture across the more than 200 million acres of oak forests and mixtures in the United States. It is not a manual or how-to guide for oak silviculture, but rather a source of ideas on how to think about oak forests as responsive ecosystems.
Citation: Johnson, P. S., S. R. Shifley, and R. Rogers. 2009. The Ecology and Silviculture of Oaks, 2nd ed. Wallingford, UK: CABI Publishing. 580p. ISBN 978-1-84593-474-3.
Web -enabled database site for Center for Forest Mycology Research expanded
The culture collection and herbarium maintained by the Center of Forest Mycology Research (CFMR) in Madison, Wisconsin is one of the largest fungal “libraries” in the world. The collection specializes in fungi associated with wood and contains both living fungi and dried reference specimens, which are used by researchers worldwide in studying forest pathology, disturbance biology, fungal genetics, distribution of invasive species, and impact of climate change on forest ecosystems. The CFMR’s web-enabled database, accessible at http://www.fpl.fs.fed.us/research/centers/mycology/culture-collection.shtml, has recently been enlarged and updated.
It enables researchers around the world to access files about the CFMR’s 13,000 cultures and 50,000 dried specimens representing over 1000 fungal species in a user-friendly software interface. NRS scientists at CFMR have developed molecular tools---including “genetic fingerprinting” using DNA sequencing and cloning techniques---to detect and identify fungi both in culture, as well as directly from wood and other substrates. These techniques are currently being used to identify fungi associated with wood decomposition under different climate regimes and fungi associated with bat hibernacula for management of white-nose syndrome (a devastating disease of bats in the Eastern U.S.) as well as for tracing the spread of destructive tree root pathogens in U.S. forests.
DNA tool detects white-nose syndrome fungus in bat caves
Over one million bats, including rare and endangered species, have succumbed to white-nose syndrome, a disease first observed in 2007 in Upstate New York. This lethal disease is caused by the fungus Geomyces destructans, which continues to spread eastward across the United States. Assessing the distribution of G. destructans in environments occupied by hibernating bats is critical for WNS surveillance and management. NRS scientists Daniel Lindner and Jessie Glaeser are collaborating with the USGS Wildlife Health Laboratory in Madison, WI, to characterize the distribution of G. destructans in cave sediment samples from bat hibernation sites in the eastern United States.
They are using molecular identification techniques that Lindner helped to develop. The fungus was found in cave sediment samples from states where WNS is known to occur, suggesting that the fungus can persist in the environment, but was not found in caves outside the region of known infestations; Closely related fungi, some previously unknown to science, were also found. Bat biologists are using this research to devise strategies to save these animals from extinction.
United States Geological Survey; Wildlife Health Laboratory; Symbiology Inc.
Landscape-level deer herd reductions restore forest understory plant communities but not species diversity
White-tailed deer overbrowsing has altered forest understory plant species (forbs) diversity throughout eastern North America. Since 2001, NRS scientist Alejandro Royo has tracked the response of herbaceous plant communities to deer herd reductions throughout the 70,000-acre Kinzua Quality Deer Cooperative (KQDC) in northwestern Pennsylvania.
Royo and his partners---forest managers from the Allegheny National Forest, the Bradford Watershed, Forestry Investment Associates, the Collins Pine Company, Sand County Foundation, and RAM Forest Products---found rapid, dramatic increases in overall forb and shrub cover of deer-palatable understory plants, such as trilliums and Canada mayflower, but no changes in plant species diversity. Thus, controlling deer alone may not promote diversity in overbrowsed, species-poor forests without additional restoration strategies. These results are being incorporated into a vegetation monitoring proposal by the Pennsylvania Bureau of Forestry for use in its 2.5 million acres of state forests.
2009 Research Highlights
Training managers to use natural models for ecological silviculture
The Northern Research Station is a founding member of the Conservation Forestry Network (CFN), which aims to improve forest management across North America. The CFN works by bringing together experts, land managers, stakeholders, and decision-makers in workshops that focus on the application of ecological principles to forest management.
- The Forest Guild
- Conservation Forestry Network
- Society of American Forests (SAF), Ecology and Range Working Group
- West Virginia University
- Maryland and Delaware SAF
- University of Wisconsin-Stevens Point
- University of Wisconsin-Madison
- Wisconsin Department of Natural Resources
- Chequamegon-Nicolet National Forest
- University of Washington
- Jones Ecological Research Center
Wood-based energy systems and potential effects on roundwood demand and supply
Planning for energy utilization requires information on the availability and future utilization trends of woody biomass from forests. NRS scientist Jan Wiedenbeck and a partner at Pennsylvania State University identified 342 facilities in the northeastern United States that use pulpwood or “energy wood.” Eighty-four percent of these facilities are in business to produce an energy-related product; 16% use it to fuel their internal operations.
- Dr. Chuck Ray, Pennsylvania State University
Developing emerald ash borer-resistant ash
Ash timber is valued for applications requiring strong, hard wood. In the urban landscape, ash trees are important street trees, as they sequester pollutants, conserve energy by provide shade, and shelter urban fauna. The emerald ash borer (EAB), an exotic beetle from Asia, is attacking and killing all ash trees in North America. First identified in Michigan in 2002, the EAB has since been detected in Ontario, Ohio, Indiana, and at least nine other states.
Family forest landowners and stewardship activities
Family-owned forest lands provide goods and services that benefit both owners and society, including recreation, timber, wildlife habitat, and clean water. To encourage landowners to undertake stewardship practices to protect and sustain their forest resources, government agencies use a variety of approaches, including incentives, tax relief, technical assistance, and educational programs.
- Dr. Michael Kilgore, Dr. Steven Taff, and Joseph Schertz, University of Minnesota
Delivering best science for sustaining mixed oak forests
Northern Research Station scientists achieved two milestones in science delivery, working with state forest management agencies in Pennsylvania and Ohio. Since 2000, NRS scientists have worked with the Pennsylvania Bureau of Forestry to organize science-based knowledge about oak ecology and management into guidelines for inventory, analysis and sustaining mixed-oak forests in the region. At the same time, these agencies have also identifed research gaps and begun studies to close them.
- Pennsylvania Department of Conservation and Natural Resources, Bureau of Forestry
- Ohio Department of Natural Resources
2008 Research Highlights
Studies track resurgence of endangered Kirtlands Warbler
Two studies by Northern Research Station scientists and collaborators spell good news for the endangered Kirtland’s warbler. Once reduced to only 167 males in 1984, the Kirtlands warbler now exceeds 1,300 with an ever-expanding territorial range.
Researchers analyzed 26 years of data to determine how forest management practices might be affecting the birds. Efforts to create suitable habitat and to establish more areas regenerated through wildfires were reported as having the most significant impacts on the warblers’ recovery.
Another study demonstrated a continuous range expansion from the warblers’ historical nesting area in lower Michigan. NRS-developed management guidelines that included increasing the amount of created habitat, providing larger stands of jack pine saplings and ensuring adjacent land had suitable-aged jack pines. As a result of an expanding population, 28 Kirtland’s warblers were found in six Wisconsin counties.
Long-term studies are vital for monitoring the success of large-scale restoration programs. Expanding habitat also reduces the vulnerability of extinction from an isolated event. The end result is what researchers are finding: a rebounding and more viable population. More>>
Habitat suitability program wins national conservation award
A consortium of wildlife and mapping specialists developed a computer program that helps land managers assess the range and habitat needs of 40 bird species with priority management designations. The GIS-based Habitat Suitability Index was developed from 2006-2008 and received a 2008 Wings Across America award for Research and Management Partnerships.
The Index provides a novel tool for conservation planners to use when developing population goals and habitat objectives for a specific area. It will help them better plan, monitor, and achieve bird conservation targets.
The tool is already being used by a regional partnership spanning 10 states in conjunction with the U.S. North American Bird Conservation Initiative. More>>
Guidebook, workshops teach methods for regenerating oak populations
Northern Research Station scientists and their collaborators have taken a proactive step in helping land managers turn the tide against decreasing oak populations in the United States. A recently released guidebook and a series of weeklong training courses are teaching forest managers how to successfully regenerate the once stable species.
Information in “Prescribing Regeneration Treatments for Mixed-Oak Forests in the Mid-Atlantic Region” had been around in bits and pieces for several years, said NRS researcher Pat Brose. However, it wasn’t until August 2008 that all the information was consolidated into a single publication.
Brose and his fellow researchers have taught the practical applications of their research to more than 400 forest managers from 12 different states through intensive training sessions in Pennsylvania and West Virginia. Plans are now underway to expand those trainings into neighboring Ohio as well. More>>
- Pennsylvania Bureau of Forestry
- Pennsylvania State University
- Allegheny National Forest
Forest simulation program accounts for impacts from private forest-owners
Many National Forests in the eastern United States are interspersed with sizeable land-holdings from corporate and private landowners. The impacts of forest practices, such as timber harvesting, parcelization and even land used for recreation, from these individuals can have significant implications on the ecological goals of public land officials.
Northern Research Station scientists have developed a way to incorporate land management strategies of private forest-owners into the forest simulation program HARVEST to project their impacts on landscape fragmentation and ecological sustainability. With this information, public land managers can mitigate the accumulative effects of various forest practices within their own management strategies.
The goals of public land managers and private land-holders often conflict. This latest research, however, gives public land managers a cooperative tool for achieving landscape objectives, even when they don’t manage all the land. More>>
2007 Research Highlights
Forests and floods: What we know
Lingering questions about the relationship between forest management and flood severity were answered with the release of three NRS publications in fall 2007. NRS scientists and collaborators concluded that 1) Most hydrologic models are not designed to handle extreme events, such as flooding; therefore such models must be used as predictive tools with caution; and 2) The amount and intensity of rainfall are the main determinants of the level of peak flows and during very large storms, harvesting activities did not significantly affect peak flows.
- Virginia Tech
- West Virginia Division of Forestry
Winter ranges of North American birds are shifting northward
NRS scientists and cooperators determined that the northern boundaries of bird species’ winter ranges shifted northward, on average 26.7 miles, from 1975 to 2004. While some regional or human-related activities could affect these range shifts, the pervasiveness of this pattern suggests global scale factors, such as climate change, are primarily responsible.
- University of Missouri
Projecting potential impact of global change on Eastern forests
NRS researchers expanded their online Climate Change Atlas to encompass 134 tree species and 147 bird species, more accurate modeling tools, and newer climate models. The Website (www.nrs.fs.fed.us/atlas) illustrates potential species distribution in response to various climate change scenarios and is a resource for researchers, foresters, and other partners studying global climate change.
- University of California, Davis