shade metals

Hemlock Tree Extinction

Sara & CesarComment

Harvard university has 3500 acres of woodland that it uses for research and teaching.  A project started in 2005 is attempting to measure the best way for the Eastern Hemlock tree to go extinct. 

 White trunks dot this forest where all the Hemlock trees have been suffocated. The Great Smokey Mountains National Park that stretches between North Carolina and Tennessee has already seen near total extinction of the Hemlock tree. There is hope that the pest will not be able to spread into Canada because of the cold winters, but in the southern US, Hemlocks will soon disappear from wild land.

White trunks dot this forest where all the Hemlock trees have been suffocated. The Great Smokey Mountains National Park that stretches between North Carolina and Tennessee has already seen near total extinction of the Hemlock tree. There is hope that the pest will not be able to spread into Canada because of the cold winters, but in the southern US, Hemlocks will soon disappear from wild land.

 Signs of the woolly adelgid, suffocating the tree one leaf pore at a time

Signs of the woolly adelgid, suffocating the tree one leaf pore at a time

In 1951, the woolly adelgid, a pest that attacks the Eastern Hemlock and slowly suffocates it, was accidentally introduced to North America.  Where it doesn't severely damage the trees in Asia, it kills the Eastern Hemlock that grows from Georgia up through Canada.  There will most likely be no “cure” for this bug, and the weather is warming in Canada which allows the pest to travel farther up north.

 

Some land owners are harvesting their stock of hemlocks before they are infected so that the wood can be sold before it begins to rot. 

The question the researchers are asking is if there is a “preferred” way for the population to go extinct.  How is the rest of the forest affected if the trees are left to rot or are felled en masse.  An article about the Nature Conservancy's plan to manage the pests is here.

 Dense and sheltering Hemlock stands are the preferred shelter for many animals against wind and winter cold / image:  Nebraska Knoll Blog

Dense and sheltering Hemlock stands are the preferred shelter for many animals against wind and winter cold / image: Nebraska Knoll Blog

“Hemlock forests are remarkable for their shadiness, low temperatures, and stillness.

In stark contrast to the brightness allowed by the leaves of a hardwood forest, the needles and branches of hemlock trees are arranged in horizontal, overlapping patterns, absorbing 99% of available light before it reaches the ground. By blocking the light from seedlings growing on the forest floor, the shade-tolerant hemlock ensures a forest in which it alone dominates: few other species of trees can tolerate such dim conditions. 

The incredibly unique habitat that hemlocks provide for a number of species (including red-backed salamanders, soil arthropods, web-building spiders, hemlock trout, migrating birds, barred owls, porcupines, fisher weasels, snowshoe hares, and moose) underscore the important role hemlock forests play in adding to the diversity of ecosystems on a regional scale.”  

- Caludia Villar / Harvard Forst Blog

 A female grosbeck perched in a Hemlock tree

A female grosbeck perched in a Hemlock tree