 Here’s
what the botanists have to say about the 2007
Leaf-Peeping Season in Plumas County:
Plumas National Forest Chief Botanist/Ecosystems
Manager Linnea Hanson is predicting that fall
colors should be as beautiful as ever this year.
“We’re not really in a drought year, we just had
less water than normal,” Hanson told us. “Taking
from what I’m seeing, we think it’s going to be
pretty darn good.”
Fellow district botanist James-Belsher Howe
agrees. “The places that are dry might start
turning sooner, but they’ll drop at the same
time, which may make the peak last longer,” he
predicts.
Why do leaves change color?
Shorter periods of daylight and variations in
temperature are the cues for deciduous
(leaf-shedding) plants to prepare for winter.
They begin to shut down their food-making
process (photosynthesis) and the production of
the green pigment chlorophyll. The plants
attempt to store up their chemicals by taking
out sugars and chlorophyll from their leaves.
This slowing allows yellow and gold pigments
(called carotenoids) to slowly emerge – which
have been there all along but are masked by
chlorophyll. Red pigment (called anthocyanin),
unlike the others, is not attached to the leaf
cells, but is produced by sugars in the leaf
veins, which are trapped when veins are closed
during the fall. The intensity of the red
pigment varies depending on the sugar
concentration and acidity in the cell sap, and
the amount of sunlight the
leaves receive. The best combination for
producing intense autumn colors is dry, sunny
days followed by cool (not freezing) dry nights.
When fall weather is cloudy and rainy, and the
nights warm, the color is usually less intense.
What the plants can’t store, they must deal with
as waste. They form a special layer of cells
that severs the tissues supporting the leaves at
the branch, causing the leaves to drop.
The yearly process doesn’t happen overnight, and
unpredictable weather makes each fall foliage
season unique. Varying microclimates among
ridges and valleys generally make for a long
fall color season in Plumas County, with “peaks”
occurring at different times in different areas.
The best time to spot the most color, however,
is usually the third week of October.
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