Threat to Eastern Hemlock

Quote 1: The hemlock woolly adelgid a small, aphid-like insect native to Japan, is currently spreading unimpeded across the eastern USA and threatens the widespread decline or elimination of eastern hemlock one of eastern North America's most important tree species (Orwig and Foster 1998).

Our Interpretation:

• Spread of Hemlock Woolly Adelgid created widespread decline or elimination of the Eastern Hemlock Species across the eastern United states.  

• Eastern Hemlocks are often referred to as North America’s most important tree

 

Asthenic Loss and Property value

Quote 2: A study in residential new Jersy found that HWA caused defoliation levels of 25-50% led nearby property values to drop on average more than 7,000 USD (Holmes et al. 2005)

Our Interpretation:

• This estimate is related to the asthenic value of assigned to hemlocks in a neighborhood in 2007

• This doesn’t include cost to treat or cut down dead hemlock trees

 

Hemlock Forest Soils

Quote 3: The deep shade and acidic litter characteristic of hemlock stands result in cool, damp microclimates, low light availability, depauperate understories and slow rates of nitrogen cycling (Orwig et al. 2002).

Our Interpretation:

• When Hemlocks are removed from an area, there is a large shift in type of soil

• Nothing besides Hemlocks will replicate an Eastern Hemlock Forest/Soil Ecology

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Hemlock Ecosystem Services

Quote 4: Ecosystem services provided by hemlock forests include the protection of riparian habitat supporting Coldwater species such as trout, the aesthetic value of old growth hemlock stands, particularly on public land where trees may exceed 500 years of age.  (Holmes et al. 2005)

Our Interpretation:

• Hemlock stands are key in protecting Streams, Rivers, Lakes, or any Riparian areas.

• Hemlocks provide habitat for cold water species like trout

• Hemlock Stand may exceed 500 years old

 

Hemlock and Trout Streams

Quote 5: Stands with dense Eastern Hemlock canopies provide important watershed protection and thermoregulation of streams year-round for native Salvelinus fontinalis Mitchill (Brook Trout)  (Snyder et al. 2002).

Our interpretation:

• Canopy cover provides watershed protection and keep streams at cooler temperatures for Brook Trout year-round

• Without Eastern hemlocks protecting streams, native Brook Trout may cease to exist

 

Sources:

Holmes, T.P., E.A. Murphy, and D.D. Royle. 2005. THE ECONOMIC IMPACTS OF HEMLOCK WOOLLY ADELGID ON RESIDENTIAL LANDSCAPE VALUES: SPARTA, NEW JERSEY CASE STUDY.

Orwig, D.A., and D.R. Foster. 1998. Forest Response to the Introduced Hemlock Woolly Adelgid in Southern New England, USA on JSTOR. The Journal of the Torrey Botanical Society 125:60–73.

Orwig, D.A., D.R. Foster, and D.L. Mausel. 2002. Landscape Patterns of Hemlock Decline in New England due to the Introduced Hemlock Woolly Adelgid. Journal of Biogeography 29:1475–1487. Wiley.

Snyder, C.D., J.A. Young, D.P. Lemarié, and D.R. Smith. 2002. Influence of eastern hemlock (Tsuga canadensis) forests on aquatic invertebrate assemblages in headwater streams. Canadian Journal of Fisheries and Aquatic Sciences 59:262–275. CANADIAN SCIENCE PUBLISHING.