Hemlock trees are iconic in New York’s landscape. As the third most common tree in our forests, hemlocks are so common that we often take them for granted. In addition to being beautiful, hemlocks provide unique ecosystem services that benefit New York’s residents, human and animal alike. This is why we are so dedicated to conserving New York’s hemlock trees in the face of HWA infestations. To learn how to identify hemlocks in the field, visit our Hemlock Tree page.
The eastern hemlock (Tsuga canadensis) is a foundation species in our forests, which means that it creates the ecosystem in which it resides. Hemlocks are the base of the food web and when grouped together as a stand they create unique soil and water conditions in the forest. Hemlocks are also the third most common tree in New York State, existing as a vital component of our forests and a characteristic tree on the landscape.
In addition to being a foundation species, hemlocks are also a climax species. This means that they represent a mature and very productive forest ecosystem. Hemlocks are slow-growing and very shade-tolerant, taking a long time to reach the canopy and dominate their forest sites. If we lost our hemlock canopy, it would take ages for that canopy to recover, if at all. For these reasons, hemlocks are irreplaceable on the landscape, and their loss would render our forests unrecognizable.
In addition to creating a home for us and unique wildlife, hemlocks provide valuable ecosystem services that would not exist in their absence, making them a valuable forest resource.
Hemlocks are key players in keeping drinking water cool and clean. Their shallow, branching root systems help filter agricultural runoff and keep water clean along stream corridors and other water bodies. Hemlocks make up much of the forest along shorelines and streams, and are critical for preventing sedimentation and filtering out pollutants. Residents of New York City, Syracuse, and other municipalities in the state rely on hemlocks surrounding reservoirs and lakes to keep municipal water supplies clean.
Healthy hemlocks with dense canopies also shade streams, keeping them cooler in the summers. Hemlocks provide ideal water conditions for cold-water fishes like native trout species to reproduce and thrive. Additionally, the shade hemlocks provide keeps snow from melting until later in the spring, keeping water temperatures lower later in the season and slowing the recharge of streams for cleaner, cooler water.
In addition to providing healthy cold water fisheries, hemlocks are also home to several obligate bird species and numerous species of canopy arthropods, helping to form the base of the food web in our forests. Animals such as deer, moose, grouse, and porcupines look to hemlocks for a winter food source and for shelter away from cold and windy weather conditions. These wildlife rely on hemlock trees to make their home on the landscape.
Economic and Aesthetic Assets
Hemlocks are beautiful trees when they are healthy and have a full canopy. When hemlocks are in decline as a result of HWA infestation, their foliage becomes pale, grey and they are unable to put on new growth. After many years of infestation, hemlocks eventually begin to lose needles and branches die.
This aesthetic loss is devastating to formally pristine woods sites. For landowners, this is loss is even more critical. Dead or declining trees can be unsafe, expensive to remove, and lead to a decrease in property values.
Managing the Threats to New York’s Hemlocks
Vist our Hemlock Woolly Adelgid page to learn more about the threat that HWA poses to our hemlock trees and what we’re doing to mitigate that threat.
To learn more about managing HWA infestations on your own property, you can visit our HWA Management page.