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Hemlock Woolly Adelgid

Kelly van Frankenhuyzen talks with U.S. Forest Service experts about hemlock woolly adelgid and it's impacts on eastern hemlock forests.

  • Andrea Hille, Silviculturist, Allegheny National Forest, Pennsylvania
  • Nathan Havill, Research Entomologist, Northern Research Station, Hamden, Connecticut
  • Therese Poland, Research Entomologist and Project Leader of Ecology and Management of Invasive Species in Forest Ecosystems research work unit, Lansing, Michigan

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Ice Storm Experiment

Kelly van Frankenhuyzen talks with U.S. Forest Service experts about the Hubbard Brook Ice Storm Experiment and the importance of studying ice storms.

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[photo:] Hoosier National Forest in Indiana. [photo:] Burr Oak Cove Campground on the Athens Ranger District near Glouster, Ohio is a small densely wooded campground on the northwest tip of the Burr Oak Reservoir in Athens County. The campground has 19 camping units, including walk-in sites which offer additional seclusion to the camper looking for solitude. [photo:] A sunrise on the Midewin National Tallgrass Prairie perfectly illuminates beautiful wildflowers. [photo:] Hoosier National Forest in Indiana. [photo:] Man fishes off boardwalk at Lake Vesuvius Recreation Area.


The only thing reliable about Spring is its unreliability. In 2018, blizzards, Nor’easters, and a few gorgeous days (or so we have been told) are all par for the course. In fits and starts, winter is letting go and nature is revving up. This page brings together Northern Research Station science that relates to the season, along with links to other seasonal resources within the USDA Forest Service.  

Scientist's Perspectives on the Season

Maple Syrup / Climate Change

Young girl drilling maple tree for tapping to produce maple syrup.For anyone who likes maple syrup, spring is an important season. In 2015, U.S. sugar maple trees produced 3.41 million gallons of syrup, valued at roughly $130 million. Northern Research Station scientists recently explored how sugar maple trees (and maple syrup) may be impacted by climate change and other threats.

Researchers evaluated the current distribution of maple syrup production across 23 U.S. states and estimated the current potential sugar maple resource. Predictive models show declines in sugar maple habitat likely to occur due to climate change across many of the states in the southern and middle sections of the species distribution. In addition, a potential change in the early season growing degree days was noted, which influences the sap run across the eastern U.S.

The research had some sweeter findings as well. Some regions along the northern tier of the eastern hardwood region, which includes the country’s most established maple syrup industry in Vermont, may be able to maintain or increase capacity. In addition, further north in areas such as Maine and Minnesota, both climate change impacts and greater focus on developing sugar maple habitat could result in more viable opportunities to increase maple syrup production in the future.

-Steve Matthews, Ecologist

Northern Research Station, Delaware, Ohio

Spring Emergence of Bats


Hibernating bats. Photo by Brian Heeringa, USDA Forest ServiceTraditional symbols of spring include a skein of geese or the first robin, but a bat emerging from hibernation to skitter across the sky at dusk is just as hearty an emblem of the new season.

In the northern Great Lakes region, bats begin emerging from caves (or hibernacula) in April, when average daytime temperatures begin to reach the mid-50s but the average nighttime temperature is hovering just above freezing. After they emerge, bats will head to breeding habitat areas that are often hundreds of miles away.

White-nose syndrome, a disease that has killed millions of bats and continues to spread, has made spring a more perilous season for bats that are exposed to the disease but survive. The fungus grows on bats’ tissue, including wings and noses (thus the name “white-nose syndrome”) and causes bats to wake up from hibernation too early, which means they burn energy they cannot afford to lose.

Bats in the Great Lakes region are a major predator of nocturnal insects, eating between 300 and 3,000 insects per night. With the spread of white-nose syndrome caused by the fungus Pseudogymnoascus destructans, or Pd, many hibernating bats in the Great Lakes region have reached critically low population sizes.

A multi-agency team led by the Northern Research Station is focusing on understanding habitat use in the landscapes around hibernaculum in the fall, when bats “swarm” at hibernaculum to mate and increase their fat reserves before hibernation, and spring, when bats need to build up the energy reserves needed to migrate to breeding grounds. This research will be useful to land managers who are trying to reduce disturbance around hibernaculum to moderate any secondary effects of white-nose syndrome.

-Deahn Donner, Research Ecologist
Northern Research Station, Rhinelander, Wisconsin


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Listen to a northern long-eared bat recorded on the Chequamegon-Nicolet National Forest.


Selected Research Stories

Selected Publications

The publications listed below do not represent every study related to winter; for a more complete list of NRS publications, please visit our Publications page at:

Janowiak, Maria K.; D'Amato, Anthony W.; Swanston, Christopher W.; Iverson, Louis; Thompson, Frank R., III; Dijak, William D.; Matthews, Stephen; Peters, Matthew P.; Prasad, Anantha; Fraser, Jacob S.; Brandt, Leslie A.; Butler-Leopold, Patricia; Handler, Stephen D.; Shannon, P. Danielle; Burbank, Diane; Campbell, John; Cogbill, Charles; Duveneck, Matthew J.; Emery, Marla R.; Fisichelli, Nicholas; Foster, Jane; Hushaw, Jennifer; Kenefic, Laura; Mahaffey, Amanda; Morelli, Toni Lyn; Reo, Nicholas J.; Schaberg, Paul G.; Simmons, K. Rogers; Weiskittel, Aaron; Wilmot, Sandy; Hollinger, David; Lane, Erin; Rustad, Lindsey; Templer, Pamela H. 2018. New England and northern New York forest ecosystem vulnerability assessment and synthesis: a report from the New England Climate Change Response Framework project. Gen. Tech. Rep. NRS-173. Newtown Square, PA: U.S. Department of Agriculture, Forest Service, Northern Research Station. 234 p.

Lerman, Susannah B.; Contosta, Alexandra R.; Milam, Joan; Bang, Christofer 2018. To mow or to mow less: Lawn mowing frequency affects bee abundance and diversity in suburban yards. Biological Conservation. 221: 160-174.

Redwood, Mame E.; Matlack, Glenn R.; Huebner, Cynthia D. 2018. Seed longevity and dormancy state suggest management strategies for garlic mustard (Alliaria petiolata) and Japanese stiltgrass (Microstegium vimineum) in deciduous forest sites. Weed Science. 66(02): 190-198.

Brandt, Leslie A.; Derby Lewis, Abigail; Scott, Lydia; Darling, Lindsay; Fahey, Robert T.; Iverson, Louis; Nowak, David J.; Bodine, Allison R.; Bell, Andrew; Still, Shannon; Butler, Patricia R.; Dierich, Andrea; Handler, Stephen D.; Janowiak, Maria K.; Matthews, Stephen N.; Miesbauer, Jason W.; Peters, Matthew; Prasad, Anantha; Shannon, P. Danielle; Stotz, Douglas; Swanston, Christopher W. 2017. Chicago Wilderness region urban forest vulnerability assessment and synthesis: a report from the Urban Forestry Climate Change Response Framework Chicago Wilderness pilot project. Gen. Tech. Rep. NRS-168. Newtown Square, PA: U.S. Department of Agriculture, Forest Service, Northern Research Station. 142 p.

Matthews, Stephen N.; Iverson, Louis R. 2017. Managing for delicious ecosystem service under climate change: can United States sugar maple (Acer saccharum) syrup production be maintained in a warming climate? International Journal of Biodiversity Science, Ecosystem Services & Management. 13(2): 40-52.

Motley, K.; Havill, N.P.; Arsenault-Benoit, A.L.; Mayfield, A.E.; Ott, D.S.; Ross, D.; Whitmore, M.C.; Wallin, K.F. 2017. Feeding by Leucopis argenticollis and Leucopis piniperda (Diptera: Chamaemyiidae) from the western USA on Adelges tsugae (Hemiptera: Adelgidae) in the eastern USA. Bulletin of Entomological Research. 107(05): 699-704.

Potvin, Lynette R.; Lilleskov, Erik A. 2017. Introduced earthworm species exhibited unique patterns of seasonal activity and vertical distribution, and Lumbricus terrestris burrows remained usable for at least 7 years in hardwood and pine stands. Biology and Fertility of Soils. 53(2): 187-198.

Lerman, S.B.; Milam, J. 2016. Bee fauna and floral abundance within lawn-dominated suburban yards in Springfield, MA. Annals of the Entomological Society of America. 11 p.

Pan, Yude; Schimel, David. 2016. Synergy of a warm spring and dry summer. Nature. 534: 483-484.

Reidy, Jennifer L.; Thompson, Frank R.; Amundson, Courtney; O'Donnell, Lisa. 2016. Landscape and local effects on occupancy and densities of an endangered wood-warbler in an urbanizing landscape. Landscape Ecology. 31(2): 365-382.

Reilly, James R.; Hajek, Ann E.; Liebhold, Andrew M.; Plymale, Ruth. 2014. Impact of Entomophaga maimaiga (Entomophthorales: Entomophthoraceae) on outbreak gypsy moth populations (Lepidoptera: Erebidae): the role of weather. Environmental Entomology. 43(3): 632-641.


Last Modified: April 23, 2018