Hemlocks are a critical component to our beech-maple-hemlock forest ecosystems:
- The shade hemlock trees provide create a cooling affect of rivers and creeks, which can impact fisheries.
- Hemlock trees stabilize and protect our dune and riparian systems.
- Hemlock trees provide critical winter habitat for birds.
- Hemlock trees provide winter cover and food sources for deer and other game animals.
- There are more than 170 million hemlock trees in Michigan.
Hemlocks stabilizing the land along the Pigeon River at Hemlock Crossing Park, photo by David Michael Lawson.
How it can affect fisheries
Hemlocks grow along river corridors and creeks where trout and other game fish spawn. The loss of hemlocks and the shade they provide these waters would likely increase water temperatures. If they become too high, water will be too warm for fish to spawn.
Less oxygen and pH changes in the water will alter aquatic insect population, which is an important food source for game fish.
How it can affect hunters
Hemlock trees, especially in northern Michigan, provide winter cover to deer. Young hemlocks are also a food source for deer and other animals.
Written by: Deborah G. McCullough
Professor, Dept. of Entomology and Dept. of Forestry, Michigan State University
Hemlock, a notably shade-tolerant, long-lived species, is an important resource for wildlife and plays an integral role in many ecological processes in forests. Dense hemlock canopies provide deep shade, critical winter cover, food and habitat for several bird and mammal species. In the northeastern United States, hemlock mortality caused by HWA altered soil temperatures, nitrogen cycling and decomposition rates. These changes subsequently affected other plants and animals as well as forest structure. Hemlock is typically shallow-rooted and often grows in riparian areas near streams and rivers or on sites with high water tables. In eastern states, widespread hemlock mortality resulting from HWA increased erosion, raised water temperatures, reduced water quality and altered communities of aquatic invertebrates.
Eastern Hemlock in Hemlock Crossing County Park by Annette Hoffman, Nettie Marie Photography
Inventory data from 2014 indicate that more than 173 million hemlocks grow in Michigan forests, and thousands more have been planted in landscapes. Though hemlock is most abundant in the extensive forests in northern lower and upper Michigan, it is locally common in other areas of the state in private woodlots, game management areas, public parks and recreation areas. Much of the hemlock resource in Michigan forests consists of relatively old trees. This age-class distribution reflects years of preferential browsing by deer on young, regenerating hemlock. More than 93 percent of the 1.08 billion cubic feet of hemlock volume in Michigan consists of sawtimber-sized trees.