Sustain our Nation’s Forests and Grasslands
From partnerships that bring land managers and scientists together to solve problems, to models that guide long-term forest planning, to research that improves the effectiveness of efforts to restore oak savannahs and woodlands, Northern Research Station science makes a difference for people and the environment. This month , we feature a scientist, a product, research and a partnership that demonstrate how we contribute to sustaining the Nation’s forests and grasslands.
The Forest Atlas of the United States combines state-of-the-art inventory and monitoring information with tree pollen counts, mill surveys, ownership records, bird observations and more to tell stories about the value of our nation's forests and the challenges they face.
Science was not Eric Gustafson’s first career goal. After teaching biology in a 2-year college, Gustafson decided to make academia his career and went back to school for a doctorate degree. There he discovered what was then the new field of landscape ecology and the use of computer models to simulate landscape change; a postdoc position with the Northern Research Station in Rhinelander, Wisconsin, swept away any residual interest in becoming a college professor.
Now a research landscape ecologist, Gustafson’s Forest Service career has had one primary objective: to develop a tool that would reduce the uncertainty of forest management decisions. Gustafson is part of a small team of Forest Service and university scientists that developed LANDIS, a model that allows managers to see how key variables (climate, natural disturbances such as wildfire, destructive winds and insect pests) as well as management decisions combine to shape the landscape. “It has the power to allow managers to ask ‘what if?’” Gustafson said. “It lets them see how management actions will play out on the landscape over time.”
One of Gustafson’s current projects – and a major milestone for LANDIS – is assisting the Wayne National Forest in Ohio with using the model to revise the Forest Plan. His team will not only run the model, but also train Wayne National Forest staff to use it. “It is a very complicated model,” Gustafson said. “In addition to contributing to the Forest Plan, we want to leave staff with the skills they need to continue using LANDIS to address new questions as they arise.”
Aside from his short career teaching biology, trees have been the focus of nearly all of Eric Gustafson’s working life, beginning with working on his family’s tree farm in Vermont when he was growing up. Studying forest ecosystems and ecosystem change during the week has made outdoor recreation all the more engaging for Gustafson. “It adds to the richness of nature when you understand that a disturbance may look catastrophic, but the ecosystem usually bounces back because it’s resilient,” Gustafson said.
Managing Appalachian hardwood stands using four management practices: 60-year results
An accessible walking trail in the Fernow Experimental Forest, located on the Monongahela National Forest in West Virginia, meanders along a west-facing slope covered with hardwood trees where over 60 years ago a forest management study was initiated. The Cutting Practice Level Study was designed to help forest managers develop more sustainable forestry practices while optimizing yields following an era of exploitative logging. The study is ongoing, but recently Northern Research Station scientists summarized results to date.
The Cutting Practice Level Study began in 1948 and involved implementing different forest management treatments assumed at the time to range from best to worst, including two variations of single-tree selection (applied 7 and 8 times respectively or every 10 years), a 39-centimeter diameter limit harvest (applied 4 times or every 20 years), and a commercial clearcut (applied one time). A control plot where no harvesting occurred was also included in the study. Over the decades, scientists supervised the treatments, monitored the plots, and assessed productivity, diversity, quality of the trees, and value.
In this case study, productivity was maximized with diameter-limit harvesting, diversity was best with even-aged management or no management at all, and quality and value were somewhat better with single-tree selection. Each treatment had its pluses and minuses, suggesting that no one approach to forest management or silviculture can deliver all of the desired management objectives. This study illustrates that landowner objectives are essential for determining the most appropriate management approaches.
“From its inception the Cutting Practice Level Study has served as a training ground for foresters and a demonstration area where people can view and learn about the dynamics and trade-offs of forest management practices,” said Tom Schuler, research forester and scientist-in-charge of the Fernow Experimental Forest. “Looking to the future, we are working on linking this site to similar forest management case study sites in the Northeast and Midwest to address broader regional forest concerns.”
Silviculture to restore oak savannas and woodlands
Oak woodlands and savannas are open canopy ecosystems rich in both plant and wildlife diversity that were once quite common in the landscape. They developed under variable fire regimes that kept tree canopies open and provided seedbeds optimal for oak germination and seedling growth as well as development of a rich and productive native ground flora of grasses, sedges, forbs, and shrubs. One effect of suppressing fire is that these woodlands and savannas have nearly disappeared and been replaced by closed canopy forests. Researchers with the Northern Research Station and their collaborators are working to develop approaches land managers can use to restore woodlands and savannas, and the multitude of benefits they provide.
If fire exclusion is the problem, reintroduction of fire, through prescribed burning might seem like the simplest solution. However, scientists soon realized that use of prescribed fire alone does not model natural fire regimes in intensity, variability and frequency. Low intensity prescribed fires were found to reduce litter cover and the density of midstory trees and tall shrubs, but not remove enough canopy to allow adequate amounts of light to reach the forest floor for productive floral growth and reproduction. If intensity of prescribed fire is increased to reduce the density of overstory trees, then it makes it difficult for managers to control which trees are killed.
Ultimately, scientists found that a combination of timber harvesting, mechanical/chemical thinning and prescribed burning creates conditions most favorable for restoring oak woodlands and savannas. Scientists are still conducting studies to determine the best sequence and level of treatments to achieve desired results with a variety of oak species in a variety of locations in the Midwest.
“Restoration of these iconic oak woodlands and savannas serves to increase diversity and forest complexity across the landscape,” said Dan Dey, a research forester and project leader with the Northern Research Station in Columbia, Missouri. “With greater community diversity in structure and composition, these ecosystems and landscapes will be more resilient to environmental stresses including increases in temperatures, droughts and other extreme weather events. Also, healthy and productive natural communities are more resistant to invasion and competition from non-native species.”
In the mid-1960s, forest managers in northwestern Pennsylvania were faced with a landscape-scale forest management crisis – hardwood forests that dominate the region were failing to regenerate. Managers realized that rigorous science could help them identify causes and solutions to the problem and provided support for an expanded Forest Service research presence in the region. Working together, scientists and managers identified issues, designed studies, selected study sites across diverse land ownerships, installed treatments, and communicated results. The entire effort came to be known as SILVAH (short for Silviculture of Allegheny Hardwoods) and is still going strong 50 years later.
Early SILVAH research established that the key to regeneration success in hardwood forests was establishing abundant advance regeneration. In the 1960s, deer were the most significant impediment to regeneration in Pennsylvania. A structured decision-making framework was developed and incorporated into a computerized decision support tool and a week-long training session to help managers apply result results on the ground. Regeneration success improved from about 50 percent to more than 90 percent, and changes to deer management policy contributed to long-term advances in sustainable forests. Two leading papers from the deer research alone have been cited more than 1,100 times.
Annual SILVAH training sessions have hosted nearly 2,500 professionals from 30 different states and 4 countries since they began in 1977. “I would say SILVAH training has resulted in some of the best forest managers in the country,” said Dan Devlin, State Forester of Pennsylvania. Tony Scardina, Forest Supervisor on the Wayne National Forest in Ohio, agrees. “SILVAH undoubtedly helps land managers make better on-the-ground decisions,” Scardina said.
Over the course of 50 years, SILVAH has brought researchers and managers together into a community of practice in which rigorous science provides answers to real-world problems. The work has expanded from regeneration failures to a full suite of northern hardwood and mixed oak forest management research, including sugar maple and black cherry decline, barriers to oak regeneration, fire behavior and fuel models for prescribed burns, invasive species management, cerulean warbler habitat, and more.
Susan Stout, a research forester who was instrumental in developing SILVAH over the course of her career, said that the SILVAH collaboration has been beneficial on many levels. Management partners benefit through the network of scientists and managers, and research benefits through constant feedback from early adoption of research results by managers. Perhaps most importantly, forests benefit. “At this summer’s oak training session, I walked under a 17-year-old forest of gorgeous oak poletimber that received an experimental prescribed fire just before the very first Oak SILVAH training session in 2000,” Stout said. “It is wonderful testimony to the value of collaboration.”