September 26, 2012
Autumn In New England Losing Some Of Its Vibrant Colors
April Flowers for redOrbit.com - Your Universe Online
New England is famous for its fall foliage; the vibrant reds, yellows and oranges that make the forest look like a patchwork quilt and the ground look like it is covered in confetti. And each year, thousands of visitors flock to places like the Massachusetts' Berkshires or Litchfield, Connecticut to take in the majestic beauty of the Earth changing seasons.
David Foster, ecologist and principal investigator at the LTER, says that autumn's colors were different a century ago, or even half a century ago, and they will most likely continue to change.
The LTER maintains 26 sites around the world in ecosystems ranging from forests to deserts, and grasslands to coral reefs.
"The brilliant fall foliage so emblematic of New England forests was not always so, as the history of Harvard Forest shows," says Saran Twombly, LTER program director. "Today the current, rapid changes linked with climate are unpredictable, threatening both the forests and our deep appreciation of them."
Most of the changes are the result of human activity. Land use changes, introduced pests and diseases that destroy the forests, and climate changes from fossil fuel emissions all contribute to the changes. So far, the timing of the leaf color change has stayed more or less the same each year, although out-of-sync weather conditions can push it forward or backwards.
In the early 1900's, the New England landscape south of Maine, once famous for its brilliant maples, was covered by white pines that encroached on abandoned fields and fallow pastures. As the pines were harvested, deciduous trees such as maples, oaks, birches and others replaced them which led to blazing autumn colors all across the landscape.
Although American chestnuts, with their bright yellow autumn foliage, were common in these forests, the mature growth trees were almost all killed off by an introduced fungal disease known as the Chestnut Blight.
Now, only small sprouts remain of the chestnut forests.
"Our forests would have produced more yellows and fewer reds with chestnuts in the mix," says Foster.
Sugar maples, in an abundant amount, turn the forests a striking red in eastern Massachusetts and coastal southern New England due to extensive planting along roadsides during the 18th and 19th centuries. Sugar maples were also an important commercial commodity during this time, as they provided a source of sap for maple sugar.
Currently, the maples are at the southern end of their range in Massachusetts, but because of increasing temperatures they will probably move north over the next century.
"Over time," Foster says, "the autumn colors of our forests may fade as conditions become less favorable for northern trees such as sugar maples."
As the colors fade, the effects will be felt not only throughout the ecosystems, but also within the economic infrastructure of the region since the area is largely dependent on the tourism that is attracted to its colorful foliage.
Ashes, dogwoods and other trees that are left behind may also face diseases that are already spreading through the forest and are further exacerbated by warmer temperatures.
Some trees use the bright colors of fall as a defense mechanism, repelling insects and keeping them from laying eggs on the leaves, thereby reducing the damage to the forests the following year.
Birch trees bright yellow leaves may be a "go away" sign to egg-laying insects. The color is a clue that the leaves are unpalatable or toxic, deflecting the insect attacks to plants that don't have such defenses.
Environmental changes and diseases affect more than just deciduous trees, however. The loss of evergreens may also have an effect on autumn colors. Hemlocks, which are common in valleys, on steep slopes and along streams, are disappearing from the Northeastern forests because of an introduced insect, the woolly adelgid.
At Harvard Forest, hemlocks are infested with the woolly adelgid and will die over the next few years. It is not yet clear how far the pests will move, but as the hemlocks fall they will be replaced by black birches, whose leaves turn a bright yellow in fall.
Drought can play a large role as well, causing the trees to lose their leaves prematurely or turn color earlier than usual. The colors may be faded or look washed out due to a lack of moisture.
Warming temperatures, insects, diseases, changes in land uses and droughts are all changing the forests of the Northeast.