The Destruction of the Eastern Hemlocks. A Little Fly Will Save Them


The dying forest is composed of many different species of trees that lose their leaves every winter – oak, birch, ash, maple, poplar. If an ash tree disappears from a decaying forest – because it was killed by an emerald spewing ash, perhaps – other tree leaves are killing. Hemlock forests are dominated by one type of tree. They grow on numerous, stagnant homogeneous green stems that live 365 days a year. If hemlock disappears from a hemlock forest, not much will be left.

Hemlocks are a foundation species, meaning they play an important role in the structure of ecological communities. Their biggest contribution is the deep shadow they create. Only one percent of the sunlight hitting a hemlock canopy was able to reach the forest floor. Branches with hairy branches grow into the ground instead of going into the light, creating a muffled dome. The temperatures under the green tent can be as much as 10 degrees Fahrenheit colder than the outside world at the top of the tree and another 5 to 10 degrees colder at its base.

In the winter, the tent keeps the snow away from the ground. One gathers around the circumference of the hemlock branches, safe from the deep snow that has accumulated under the leafless trees. Torn grout and restricted owls nest in the upper hemlock canopies. The snowshoe hares nibble on its green branches. Porcupines that dig into the skin make it tannin-rich. In the spring, as the sun sets and the snow and ice melt elsewhere, hemlock preserves the snow circles on their trunks, which slowly seep into nearby creeks and cooler streams. Brook trout rely on cooling infusions of frozen water, as do many species of salamander, frog, toad, and fly.

People also know, even if they don’t know it. Hemlocks use water more conservative than hardwood tree species because their thick branches create wet and cool microclimates. “If you have hemlocks along streams that are replaced with hardwood that uses a lot of water, there’s a possibility that the streams will dry up, at least in the summer,” said Orwig, the Harvard Forest ecologist. Those rivers are used for swimming, fishing, and recreation-a major part of the Northeast. regional identity. And wherever they grow, hemlocks provide financial and financial benefits that people enjoy. A study looking at hemlock declines in central Connecticut and Massachusetts over the past five years in nine counties saw a corresponding decline in property values ​​of $ 105 million.

“Most people just look at hemlocks as this green thing,” says Whitmore, from Cornell. “But then you drill ahead and you see all the different important ecosystem-related activities related to cooling and climate that they’re doing.”

And hemlocks aren’t just great for critters and people who live nearby. They are also good at trapping carbon dioxide.

Hemlocks can absorb approximately 12 metric tons of carbon dioxide per two and a half acres, according to a 2002 study compared hemlock to other tree species. The rest of the CO2 than the oak and pineosa pinosa trees in the study. But adelgid wool is able to transform hemlocks from carbon sinks to carbon sources. That happened in 2014 at Harvard Forest. The researchers documented a hemlock stand that started producing carbon instead of following it up. “The forest can act as a source of carbon that loses hemlock,” said Orwig, who helped document the transfer from the sink to the source of Study in 2020, say.

A former Harvard study showed that adelgid wool could take 8 percent of the bite from forest carbon sequestration capabilities between 2000 and 2040. But that study and others predict that hardwood tree species , and a useful tree called black birch, which will eventually replace the dead and dying hemlock — aka fashion researchers have already noticed in the Northeast woods. By 2040, Harvard’s study projects that those black birch will get 12 percent. labi pa carbon than the hemlocks they replace. But in the short term, that 8 percent reduction in carbon sequestration is a factor, says Audrey Barker Plotkin, a senior Harvard Forest scientist who has spent years studying the invasive effect of hemlocks.



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