Woolly Bully: Monitoring the Impending Hemlock Woolly Adelgid Infestation

EarthzineDEVELOP Spring 2017 Article Session, DEVELOP Virtual Poster Session

This article is a part of the NASA DEVELOP’s Spring 2017 Article Session. For more articles like these, click here

A NASA DEVELOP team uses Earth observations to provide conservationists with tools to combat invasive hemlock wooly adelgid in the pristine ecosystems of upstate New York.

Image A: Damaged eastern hemlock from hemlock woolly adelgid infestation. Image Credit: Jason Van Driesche, Bugwood.org


Sara Lubkin

Sean McCartney

Madeline Ruid

Rachel Soobitsky

Ariel Walcutt

Eastern hemlock (Tsuga canadensis), is a foundation species ‰ÛÒ one that is necessary for an ecosystem’s structure. Hemlock trees grow on steep slopes near streams, where the roots stabilize the soil and prevent erosion, while branches offer food and shelter to dozens of other species. But hemlocks also regulate soil chemistry, nutrient recycling, and light availability. Without hemlocks, the ecosystem wouldn’t exist.

Adirondack Park has the highest density of hemlocks of anywhere in New York state (1). Towering stands of old growth hemlock have been protected from loggers and development for more than 200 years, but the Adirondack’s pristine forests are now threatened by a tiny sap-feeding insect: the hemlock woolly adelgid (Adelges tsugae), or HWA. HWA is an invasive pest first observed in Richmond, Virginia, in the 1950s. It has since spread to 20 states along the eastern seaboard and decimated old growth forests throughout the Great Smoky Mountains, Shenandoah National Park, and the Blue Ridge Parkway (Image A). Now, New York’s Catskills are under attack. If the insect reaches Northern New York, the Adirondacks could suffer a similar fate.

Protecting the park is a top priority for the Adirondack Park Invasive Plant Program (APIPP). Trees can be treated to prevent infestation, but to do this, APIPP needs to identify the trees that are at risk. Adirondack Park covers 9,375 square miles, making it larger than Yellowstone, Death Valley, Grand Canyon, and Rocky Mountain national parks. Because there are few roads over the mountainous terrain, it would take decades to map these trees by hand. The hemlock trees don’t have decades; an HWA infestation can be fatal in as little as four years (2).

Brendan Quirion, APIPP program manager, noted the close proximity of the HWA. ‰ÛÏRight now, we know that the Adirondacks have the highest density of hemlocks ‰Û_ in New York. We also know that the hemlock woolly adelgid is as far north as Troy or Schenectady, just south of the park. Our goal is to make sure that hemlock woolly adelgid is found early, as it spreads northward, and that we can keep it at bay until biological control agents become available for widespread control.‰Û

Over a 10-week term, NASA DEVELOP’s New York Ecological Forecasting team at NASA’s Goddard Space Flight Center (GSFC) partnered with six organizations, including APIPP and the St. Lawrence-Eastern Lake Ontario Partnership for Regional Invasive Species Management Program (SLELO), to support efforts to prevent the spread of HWA (Image B).

Image B: An eastern hemlock twig infested with hemlock woolly adelgid (Adelges tsugae). Image Credit: Bruce Watt, University of Maine, Bugwood.org

The DEVELOP team used multispectral data from the Landsat 8 satellite and hyperspectral aircraft data from AVIRIS to map hemlock stands throughout the study area. NASA’s Earth observations allowed the team to identify conifer trees and then classify the trees at the species level throughout the landscape. These maps will provide APIPP and SLELO with a greater understanding of where hemlock resources are in the Adirondacks. Knowing where hemlock stands are located will allow for better management and allocation of resources to prevent the spread of hemlock woolly adelgid in the region.

According to Zachary Simek, Terrestrial Invasive Species Project coordinator at APIPP: ‰ÛÏThis project will provide us with a greater understanding of where our hemlock resources are in the Adirondacks. Knowing where these high quality intact hemlock forests are will allow us to choose areas that are most important to survey for hemlock woolly adelgid.‰Û

Image C: The DEVELOP team visited nearby Prince William Forest, a National Park Service site in Northern Virginia, to document thriving hemlock in one of the last few remaining non-infested hemlock stands in the state. A project partner’s words came to mind: ‰ÛÏIf we were to lose the hemlock trees to the hemlock woolly adelgid, that habitat would be significantly imperiled.‰Û Image Credit: NASA DEVELOP


[1] B. Quirion, Adirondack Park Invasive Plant Program, Personal interview, 2017

[2] ‰ÛÏHemlock Woolly Adelgid,‰Û Pest Alert, United States Department of Agriculture, Forest Service, NA-PR-09-05, August 2005

[3] J. Aukema, et al. (2011). ‰ÛÏEconomic Impacts of Non-Native Forest Insects in the Continental United States.‰Û PLoS One, 6(9), e24587.

[4] J. Spector, ‰ÛÏWhat It Would Take to Stop Invasive Pests From Destroying Millions of U.S. Trees,‰Û in Citylab by The Atlantic, 2016

Author Biographies

Ariel WalcuttåÊis a NASA DEVELOP participant at Goddard Space Flight Center working on the New York Ecological Forecasting project. She holds a master’s in Geographic Information Science (GIS) for Development and Environment from Clark University.

Sara LubkinåÊis a NASA DEVELOP participant at Goddard Space Flight Center working on the New York Ecological Forecasting project. She has a Ph.D. in geology with a minor in zoology/entomology from Cornell University.

Rachel SoobitskyåÊis a NASA DEVELOP participant at Goddard Space Flight Center working on the New York Ecological Forecasting project. She is completing a master’s at the University of Maryland inåÊGeographic Information Systems.

Sean McCartneyåÊis the center lead for the NASA DEVELOP National Program at Goddard Space Flight Center and contributed to the New York Ecological Forecasting project. He holds a master’såÊinåÊGISåÊfor Development and Environment from Clark University.

Madeline RuidåÊis a project lead at NASA DEVELOP, Goddard Space Flight Center, working on the New York Ecological Forecasting project. She has a bachelor’såÊfrom the University of Wisconsin-Madison in physical geography, cartography/GIS, and languages and cultures of Asia (Turkish).