Rooted in Research
Northern Research Station Scientists Answer Fundamental Questions about Mixedwood Forests
Today, more than one-quarter of forests in the northeastern and north-central United States are characterized as mixedwoods–a mixture of hardwoods, like oak (Quercus) and maple (Acer), and softwoods, like pine (Pinus) and hemlock (Tsuga), with neither type making up more than 80 percent of forest composition. These temperate mixedwood forests spread across nearly 47 million acres in the United States, from North Dakota to Maine and Kansas to Maryland. Yet despite their prevalence, there is much to be learned about temperate mixedwood forests. A group of Northern Research Station (NRS) scientists is working to fill in the gaps. "We call ourselves the Mixedwooders," Laura Kenefic explains. A research forester and team leader based in Maine, Kenefic was tapped in 2014 by NRS leadership, along with NRS research forester John Kabrick in Missouri, to study the northeastern temperate mixedwood forests. Since then, Kenefic and Kabrick have made wide-ranging connections with other research scientists, building a team of partners across the region, from Quebec to Wisconsin to New Jersey. This team of partners includes: Anthony D'Amato, Kenneth Clark, Daniel Dey, Christel Kern, Benjamin Knapp, David MacLean, Patricia Raymond, Nicole Rogers, Lance Vickers, and Justin Waskiewicz. "We could have just looked at a certain mixedwood forest type," Kenefic says, "but we thought, 'this is an integrative concept.' Our approach allows us to make linkages across multiple forest types (and regions) so that we can answer questions at a broader scale."
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Science Delivery Specialist
USDA Forest Service - Northern Research Station
Key Management Considerations
- Even though mixedwoods currently make up more than one quarter of forests in the northern United States, a bottleneck in regeneration and recruitment of softwoods has signaled a potential shift to hardwood dominance across the region.
- Foresters need to consider the vertical direction of natural disturbance regime. Mismatching "above" and "below" management actions can lead to instability in mixedwood stands.
- Mixedwood forests are more resilient to, and recover more quickly from, insect infestations. This is particularly significant given the dramatic impact of defoliation and tree mortality on a stand's ability to sequester carbon, which may be reduced to just 20-30 percent of pre-infestation rates.
- Common management recommendations across mixedwood forest types include managing small trees with an eye towards regeneration and recruitment of softwoods, considering species composition during every entry, and managing "two-rotation" species on a longer timeframe.