Preserving Ecosystem Services
Eastern hemlock is a foundation species that create unique ecosystems in New York’s forests. Hemlocks provide ecological benefits that support terrestrial and aquatic habitats and the wildlife that make their homes there, and so treating hemlocks ultimately protects those unique ecosystems.
Terrestrial Ecological Value
Rarity of Ecosystem
Ecosystems such as hemlock swamps have unique characteristics, which makes those stands a priority for conservation and management.
High-Quality Habitat
There are many terrestrial species that rely on hemlocks, and conserving hemlocks ensures that those creatures will also be protected. Mammals including moose, deer, and porcupines use hemlock as a food source and shelter from wind and cold during the winter months. There are also many bird species that are closely associated with hemlocks for migration or nesting sites including several warbler species and ruffled grouse. Prioritizing hemlock management to conserve biodiversity is a critical component of forest stewardship.
Proximity to Rare Plant Species
Hemlocks are part of a complex forest ecosystem. If there are hemlocks near a rare plant or animal species, preserving those hemlocks is part of the larger goal of maintaining the population of a nearby rare species. Hemlocks create unique soil conditions so hemlocks are often associated with plant species not found elsewhere.
Old-Growth Remnants
Old-growth hemlock stands have higher levels of biodiversity than young or second-growth stands and represent a climax forest ecosystem. Therefore, old-growth stands are of high ecological and historical value and preservation of those stands is a priority.
Aquatic Ecological Value
Drinking Water
Many New York watersheds provide unfiltered drinking water to nearby towns and cities. For instance, Skaneateles Lake is the water source for Syracuse, and the Catskills provide the water for New York City. Hemlocks frequently occur along the streams and lakes in the watershed, preventing runoff from roads or agriculture that could otherwise reach those freshwater sources. Hemlocks are particularly adept at preventing the runoff of nitrogen from fertilizers. Natural filtration means that many New York watersheds do not need to invest in expensive water filtration systems, keeping utility costs lower.
Unique Aquatic Ecosystems
Cold water fish species, such as trout, rely on hemlocks for keeping water cool and clean. Hemlocks directly shade streams and prolong snow melt in the spring, keeping streams cooler for most of the year. In the Delaware Water Gap, brook trout are three times more common in hemlock-dominated streams than in streams beneath predominantly hardwood canopies. Cooler streams provide ideal habitats for cold water aquatic species to breed and thrive.
Hemlocks also create unique water chemistry in nearby streams. Streams near hemlocks will have a lower pH balance, and those slightly acidic conditions support diverse stream macroinvertebrate communities, the base of the aquatic food web in many areas.