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Why Are Eastern Hemlock Trees Irreplaceable?

Posted by on Feb 23, 2017

Perspective from RTPI’s conservation intern, Heather Zimba

I think many people would agree that spending time walking in a forest can be therapeutic, being completely enveloped by the landscape’s vegetation and wildlife. I’ll bet that – if you like the outdoors – you can close your eyes right now and visualize the areas you most like to visit. One of my favorite places is a small gorge that contains a stream with beautiful natural waterfalls. The steep banks of the gorge are lined with deep green evergreen trees that overhang and provide shade along the meandering creek.

What I did not know until last year was that the beautiful evergreen trees along this creek that I treasure so much are predominately Eastern Hemlocks. These trees slow-growing but long-lived trees contribute to forest diversity and provide numerous ecological services. Hemlocks are unique in that they are extremely shade-tolerant; the ability to tolerate low light allows the hemlock to not only grow in shaded areas but also develop dense thick canopies and stands. These stands provide habitat for many species. Stands of Hemlocks can be found in very different areas ranging from ridge-tops to swamps where they provide habitat for many species. Additionally, Hemlock roots help prevent erosion along river banks their overhanging branches provide cool shade for streams during warmer months.

Another thing I have learned is that Hemlocks are the third most common tree in New York State, and that they are at risk of being destroyed by an invasive pest called Hemlock Woolly Adelgid (HWA). HWA is an aphid-like insect, originating from Asia, which veils itself under white, woolly masses as it feeds on sap at the base of hemlock tree needles. An individual tree will succumb to HWA in under a decade if an infestation goes unnoticed. This deadly bug has been progressively moving into Western New York as it has spread throughout much of the eastern United States. Early detection of HWA is critical to successfully manage the spread of this forest pest.

Heather Zimba inspects Hemlock trees for the presence of HWA during a recent survey.

Last winter I had the opportunity to volunteer with the Hemlock Woolly Adelgid Citizen Survey project in Chautauqua and Cattaraugus Counties. Throughout the months of January and February, I joined representatives from the Roger Tory Peterson Institute (RTPI), Jamestown Community College (JCC) and Chautauqua Watershed Conservancy (CWC) and several citizens like myself to survey several sites within our area for the presence of HWA. The various state forests and preserves we surveyed were breathtakingly beautiful; I thoroughly enjoyed wandering in the woods checking the hemlock trees and meeting other citizens and scientists in the area that care about the preservation of our forests. It also felt great knowing that I was contributing to a citizen scientist project that could help protect a keystone tree species by aiding in early detection efforts for an invasive pest that has already wreaked havoc on Eastern Hemlock many southern states.

Luckily, we did not find Hemlock Woolly Adelgid at any of our survey sites last year. However, HWA has been found in 25 counties in New York State; infestations have been identified in the Catskills, the Capital Region, the Finger Lakes, and other parts of Western New York. Within Chautauqua County, HWA has been detected and is being treated for in the Allegheny National Forest and the SUNY Fredonia Campus College Wood Lot. While these are currently the only known sites of HWA infestation in Chautauqua County there could be others. Therefore, it is important to continuously conduct surveys so that this pest can be caught early. With this early detection, there are more options for monitoring and treatment of this pest.

I personally enjoyed participating in the HWA surveys so much last year, that I asked if I could assist with the project year as an intern with the Roger Tory Peterson Institute. As part of my internship, I have co-led several of the HWA surveys this winter. I am happy to report that we have not yet detected any new HWA infestations, and we are hopeful that our final survey will have the same result. Please join us if you are interested in volunteering for the last 2017 HWA survey:

Hemlock Woolly Adelgid Survey at Goose Creek Valley Greenway Preserve: Friday February 24 at 12:30pm. We will be surveying the Chautauqua Watershed Conservancy’s newly established Goose Creek Valley Greenway Preserve located on Hoag Road in the town of Ashville. We will meet at 12:00pm in the RTPI parking lot for those interested in carpooling, and will meet at the entrance of the site at 12:30pm located approx. 42°05’04.9″N 79°22’35.6″W.

In addition to the Hemlock Woolly Adelgid Surveys, there are several other special Invasive Species oriented events coming up at RTPI! I highly recommend checking out these free lectures and other events; there will be something for everyone so bring your family and friends!