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PORTLAND, Maine (AP) - Clocks may not be the only thing falling
back: That signature autumn change in leaf colors may be drifting
further down the calendar.


      Scientists don't quite know if global warming is changing the
signs of fall like it already has with an earlier-arriving spring.
They're turning their attention to fall foliage in hopes of
determining whether climate change is leading to a later arrival of
autumn's golden, orange and red hues.


      Studies in Europe and in Japan already indicate leaves are
changing color and dropping later, so it stands to reason that it's
happening here as well, said Richard Primack, professor of biology
at Boston University.


      "The fall foliage is going to get pushed back," Primack
warned.


      Down the road, scientists say there could be implications not
just for ecology but for the economy if duller or delayed colors
discourage leaf-peeping tourists.


      Phenology is the study of timing in nature, whether it's
crocuses emerging in the spring, leaves falling from trees, or
Canada geese heading south for the winter.


      And it's tricky business for fall foliage.


      The budding of plants each spring is tied almost exclusively to
warming temperatures, while fall's changing colors are linked to
cooling temperatures, decreasing sunlight and soil moisture.


      The brilliant colors associated with fall happen when production
of chlorophyll, the green pigment in plants that's crucial to
photosynthesis, slows down as the days get shorter and the nights
grow longer. That exposes leaves' yellow, red and orange pigments
that are normally hidden from view.


      How and when that happens depends on temperatures and moisture
levels. In some years, the colors are more vibrant than others.
Further complicating matters: A tree that's stressed may simply
drop its leaves, with no color change, or brown leaves.


      "Fall is still an enigma," said Jake Weltzin, executive
director of the National Phenology Network in Arizona and an
ecologist with the U.S. Geological Survey.


      Scientists caution that heavy rain, drought-like conditions or
temperature extremes can cause dramatic year-to-year fluctuations
that don't establish a long-term trend. For example, heavy rainfall
in New England this spring, followed by a deluge caused by Irene,
is causing fungal growth that's causing some trees' leaves to turn
brown and drop earlier than normal.


      William Ostrofsky, forest pathologist with the Maine Forest
Service, is skeptical about whether there's a proven link between
fall foliage and climate change.


      "I just don't know that there's any evidence to indicate
there's a trend one way or the other," said Ostrofsky, who points
out that year-to-year fluctuations make it difficult to discern
long-term trends. "I really don't think we've seen any long-term
trend, as far as I can tell."


      While there's no definitive study in the U.S., some data points
toward later leaf drop:


      - Researchers at the NASA Goddard Space Flight Center and at
Seoul National University in South Korea used satellites to show
the end of the growing season was delayed by 6 1/2 days from 1982
to 2008 in the Northern Hemisphere.


      - In Massachusetts, the leaves are changing about three days
later than they were two decades ago at the Harvard Forest 65 miles
west of Boston, according to data collected by John O'Keefe, a
retired Harvard professor and museum coordinator who's continuing
to collect data.


      - In New Hampshire, data collected at the federal Hubbard Brook
Experimental Forest in Woodstock suggests sugar maples are going
dormant two to five days earlier than they were two decades ago.


      - In Vermont, state foresters studying sugar maples at the
Proctor Maple Research Center in Underhill found that the growing
season ended later than the statistical average in seven out of the
last 10 years.
      And then there are regular folks like 83-year-old Nancy Aldrich
at Polly's Pancake Parlor in New Hampshire, who has been keeping
her own records since 1975. Her numbers show that color change is a
moving target, and she's not willing to go out on a limb in terms
of making any declarations.


      "I'm know I'm vague about it, but so is nature," Aldrich said
from the restaurant in Sugar Hill, in New Hampshire's White
Mountains.


      Scientists are getting serious, and in Maine they're enlisting
gardeners, 4-H programs, teachers, students and families in their
efforts to collect data.


      "There are signs everywhere that things are changing - how is
the question. Some species are being affected while others are
not," said Esperanza Stancioff of the University of Maine
cooperative extension and Maine Sea Grant, who has trained 195
citizen scientists to enter data online in her "Signs of the
Season" phenology project.


      To assist both backyard observers and researchers alike, the
National Phenology Network has spent the last four years coming up
with standards to be used by observers in reporting foliage color
changes. Final tweaks on the uniform reporting standards should be
completed in a few weeks, Weltzin said.


      Another part of the effort to study climate change through the
lens of fall foliage is being conducted from space by the U.S.
Geological Survey utilizing satellites from NASA and the National
Oceanic and Atmospheric Administration.


      Right now, the effort is focused on Shenandoah National Park in
Virginia, where scientists are attempting to understand the factors
that go into the metrics to ensure proper analysis of the photos
taken from above, said John W. Jones, a research geographer with
the USGS outside of Washington, D.C.


      For now, there's no reason to fear drastic changes.


      In the short term, people may have to adjust the timing of their
foliage-viewing vacations, and long-term implications for climate
change could alter the schedule altogether, Primack said.


      Foliage aficionados insist there's been nothing - not even
felled trees or record August rainfall caused by Irene - this year
to prevent the nation's leaf peepers from getting their
full-colored fix this fall. "Tourists are coming, regardless of
the weather. Many of our properties are filled to capacity," said
David West, vice president of marketing for the Pocono Mountains
Visitors Bureau in Stroudsburg, Pa.


      The bigger concern is whether tourists can afford to get out and
enjoy the sights. "The economy, I think, has a bigger impact on
what people do and their travel plans," said Lisa Marshall of the
Wisconsin Department of Tourism.

      Associated Press reporters Genaro Armas in State College, Pa.,
and Carrie Antlfinger in Milwaukee contributed to this story.
      
      
      
      

Gallery

Environmental News

Clocks may not be the only thing falling
back: That signature autumn change in leaf colors may be drifting
further down the calendar.

Climate change scientists focus on fall foliage shifts

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