Build on “Caring for the Land and Serving People”

April 2018

Northern Research Station scientists develop knowledge that is vital to restoring and sustaining rural and urban forests now and into the future. Our accomplishments include capturing the state of knowledge surrounding restoration of the iconic elm tree in a new publication, using local citizen knowledge of city landscapes to more equitably position green space across communities, maintaining a 60-year study that is answering the original question and a great deal more, and helping managers plan for the future by modeling the distribution of birds and trees in the Northeast in the face of a changing climate.  This month we feature a scientist, research, a product and partnership all focused on fulfilling our mission to care for the land and serve people. 

Environmental Education Link

Cover image from Project Learning Tree's Teaching with i-Tree Curriculum.

Project Learning Tree’s Teaching with i-Tree Unit includes three hands-on activities that help middle and high school students discover and analyze the many ecosystem services that trees provide.

Featured Scientist

Louis Iverson

Louis Iverson

Growing up on a multiple-crop/livestock farm in North Dakota’s Prairie Pothole region, Landscape Ecologist Louis Iverson was close to nature on a daily basis. “I couldn’t help but notice both the marvelous intricacies of nature and the need for careful management to sustain nature for all generations,” he said. That early introduction to the natural world was a key factor influencing his education and career path.

Being part of a research team is an important thread that runs through Iverson’s professional life. “After earning an undergraduate degree in biology/geology with a statistics minor, I joined a research team working to reclaim surface mines in western North Dakota. This ended up being my Ph.D. project,” said Iverson. In the course of his Ph.D., Iverson spent 15 months in England on a Fulbright Scholarship as a research assistant, also studying reclamation of mined lands. He then spent the next 10 years working for the Illinois Natural History Survey as a soil scientist and ecologist. Throughout his career, he has also served in many roles for three scientific societies that focus on landscape ecology.

Iverson joined the USDA Forest Service’s Northern Research Station laboratory in Delaware, Ohio, in 1992 and immersed himself in global climate change research. “I quickly learned that GIS tools could be helpful in moving the research forward,” said Iverson. Over time new scientists -- Anantha Prasad, Steve Matthews, and Matt Peters -- joined with Iverson in his studies, contributing additional expertise in GIS and ecology. Products developed from their collaboration include the “Climate Change Tree Atlas” and the “Climate Change Bird Atlas,” both of which document the current and possible future distribution of most tree and bird species in the eastern United States. Both have been widely used by researchers and practitioners; the publications have been cited over 10,000 times and the website ( has received more than 1.5 million views worldwide. 

Iverson is grateful for the stimulating, fun and productive people with whom he works and has worked with through his career. “I have the flexibility to pursue my interests and the research gaps that we may help fill,” said Iverson.  “This combination leads to work that I (and others) perceive as worthy endeavors that make a difference in sustaining our planet.”

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Featured Product

The cutting practice level study at the Penobscot Experimental Forest in Maine

[image:] Forest technician stands in the commercial (logger’s choice) clearcut portion of the CPL study at the Penobscot EF in this Forest Service photograph from 1950.

Research has been an integral part of the USDA Forest Service since it was established in 1905, and an early concern for Forest Service scientists was the toll repeated timber harvests had taken on forests in the Northeast. By the middle of the last century, more than 50 percent of managed commercial forests had been subjected to poor or destructive cutting, reducing their overall productive potential. In the 1940s and 1950s, USDA Forest Service scientists launched cutting practice level studies on experimental forests throughout the region to determine which timber harvesting practices were the most sustainable.

Scientists are still learning from the Cutting Practice Level Study at the Penobscot Experimental Forest in Maine. “Things happened over time that were unexpected,” said Laura Kenefic, a research forester and a co-author of two papers on the Penobscot Experimental Forest study. “Early researchers thought growth rates would be highest in stands where very light harvests were made every 5 years. But this was not the case. Over many decades we discovered that we hadn’t opened the canopy enough to stimulate the growth of small trees. Better outcomes were obtained from harvesting less frequently, but removing more volume each time.”

Kenefic and her co-authors, including lead author Nicole Rogers of the University of Vermont, published the latest analysis of the Cutting Practice Level study in two ways: as a journal article in “Forest Science” and as a “Picture the Past” photo essay in the Journal of Forestry. “Research is always an engaging story, and in this case we had wonderful old photos that made it even more compelling,” Kenefic said.

The Cutting Practice Level study is the longest running study on the Penobscot Experimental Forest, with close to 70 years of continuous measurement data. The study considered four silvicultural treatments for northern conifers: single-tree selection cutting on a 5-year cycle (described as high-order); single-tree selection cutting on a 15-year cycle (good); fixed diameter-limit cutting (fair); and commercial clearcutting, also called unregulated harvesting or logger’s choice (poor). Of these treatments, the single-tree selection system has emerged as the most successful in terms of maintaining residual stand quality and production potential.

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Featured Research

Baltimore Old Forest Project

[photo:] Side-by-side aerial photos of St. Peter's Cemetery in Baltimore taken in 1927 and 2015.

When we see green space, even in cities, it can be tempting to think of it as “nature” or “wilderness” that is separate from the surrounding people and communities. However, often these slices of nature have been highly influenced by people and society. Through the Baltimore Old Forest Project, scientists, with the help of local citizens, are trying to understand the relationships between patterns of green space based on past community decisions in hopes of making future decisions more equitable.

Baltimore has a long and complex social history that has influenced every aspect of the city including neighborhoods and greenspace. The presence, absence, or quality of parks, trees, and other green space is generally the result of historical decisions made by people and communities. Characteristics of green space in a given area of the city may reflect racial and economic inequalities in society. The Baltimore Old Forest project involves classifying past and current land cover types within the city to observe patterns of change over time and current distribution of green space. 

Scientists are tapping into the wealth of knowledge community members, citizens, students and others have of their local neighborhoods to do this classification using “Zooniverse,” a citizen science web portal. Zooniverse enables volunteers in local communities to look at and categorize images of areas in the city allowing for the accurate processing of large numbers of images that cannot be done as well by computers. At the same time citizens have access to and can use this data for projects, creating a mutually beneficial relationship among scientists, practitioners and citizens.

Information on land use pattern changes can help inform future environmental planning, conservation, management, and stewardship goals for Baltimore. “For example, if the project showed that certain neighborhoods had higher tree cover historically, but that current tree cover has declined, that might inform a decision to invest resources back into that community,” said Nancy Sonti, an ecologist with the Northern Research Station’s Baltimore Field Station. “Creating a more robust and equitable mosaic of green space may help solve neighborhood problems related to public health, crime, disease, and more.”

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Featured Partnership

Mining the Best Minds: Workshop Gathers Past and Current Elm Scientists Current and retired researchers gather to share knowledge of disease tolerance in American elm.

When they first waded into American elm restoration research, Northern Research Station scientists Kathleen Knight and Leila Pinchot absorbed the methods and status of research by touring research plots and greenhouses with Jim Slavicek, a project leader with the Northern Research Station’s lab in Delaware, Ohio, and a longtime elm researcher. Slavicek’s download on research methods and findings included frequent mentions of other scientists, but when Knight asked for citations, she learned that much of the research that Slavicek was referencing had never been published. “We realized that this was information that was going to be lost if we didn’t capture it in some way,” Knight said.

A partnership turned out to be the way Knight and her colleagues were able to access research related to elm ecology, pathology, biology, arboriculture, and genetics. The Northern Research Station partnered with the Manton Foundation, The Nature Conservancy and the USDA Forest Service’s Northeastern Area State and Private Forestry to bring current and retired scientists together in August of 2016 to discuss the theories, lessons learned, and ideas that had not made it into scientific literature. Knight, Pinchot, and State and Private Forestry colleague Linda Haugen co-organized the meeting. Funding from the Manton Foundation made it possible for retired scientists to travel to Columbus, Ohio. “The focus, passion, and interdisciplinary expertise of these researchers gave me great hope for the restoration of this iconic tree species,” Knight said.

Topics discussed at the meeting included the Dutch elm disease (DED) pathogen, screening elm trees for DED tolerance, mechanisms of resistance to DED, other ways to combat DED, genetics and ecology of elm, elm yellows (another disease that threatens American elm), and practical restoration methods. New relationships were forged among researchers across interagency, state, and international boundaries, and obscure information was brought to the forefront.

The workshop put Knight’s original concern – that unpublished knowledge would eventually be lost –to rest last year with the publication of “Proceedings of the American elm restoration workshop 2016”: 

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Last modified: 04/03/2018