hello dear researchers

there has been a drought in maryland this year.  some of the leaves
have turned as of this writing on 14 oct 2002, but a lot are still
green.  a co-worker told me that most likely the leaves will just drop
off this year before turning because of the drought.  im (relatively)
new to living in an area where there are colors in fall, so this came
as kind of a rude shock (i LOVE LEAF PEEPING).  tell me, is this
horrible news true?

so far, its true, a lot of them havent changed yet.  a look at the
weather.com's site (for "East Central" foliage maps
http://www.weather.com/outlook/recreation/fallfoliage/?ff_fileToView=md1)
says that we are in peak -- i am right near dc -- if i am viewing the
map coloring correctly.  PEAK?  ugh.  not even.

anyways, answer based on experience ok too.

have a great day!

Hello

I've got a degree in plant ecology, so this is a treat for me....

Marc Abrams, a professor of forest ecology and physiology at Penn
State University in State College has studied how precipitation and
temperature influence the timing of fall tree colors for 13 years,
estimated that 10 to 20 percent of the state's trees turn early in
drought years, often by the second week in September

"The early coloration is a classic drought response. The bad news is
that because it's happening now, the normal mid-October peak will not
be as brilliant. But the real test of fall colors will be whether we
get the normal cool-down period this fall." said Abrams. This was in
September 1999, after a drought in summer.

Abrams said the critical period for coloration runs from mid-September
to the second week of October, when optimum foliage is produced by
cool nights and bright sunny days.

Trees are attuned to changes in day length, light quality and
temperature. Cooler temperatures signal deciduous trees to stop
producing chlorophyll, the green pigment responsible for
photosynthesis. (Photosynthesis is the process by which trees and
other plants convert light energy to sugars and starches that serve as
the plant's food.)

As chlorophyll breaks down and disappears, it opens the way for other
leaf pigments to be visible. In some it is carotenoids, which create
the glowing yellows and oranges visible in the leaves of yellow
poplar, hickory, sycamore, honey locust, birch, beech, ginko and
certain maples. Other trees can produce another leaf pigment,
anthocyanin, that creates the reds seen in red maple, sassafras,
sumac, scarlet oak and black gum.

Drought stressed trees show their colors early, and they change fast,
so when the ones that are still green go, they might not last long

Normal peak for autumn colour in foliage is the first through the
second week of October. This year the peak could have already passed a
couple of weeks earlier as laboratory and greenhouse research
indicates that drought conditions retard the photosynthetic production
of starches, and that low starch levels mean low anthocyanin levels
and reduced coloration.

Mr Abrams was pessimistic for this year. Quoted in mid-September 2002
he said, "Every year is different with the foliage. This drought looks
like it will have the most severe effect on the foliage of any I have
seen in 16 years. Even oaks are showing signs of stress, and they are
normally drought-hardy trees."

But there is some reason for hope if the weather is not too warm.

Here's Professor Abrams again, back in 1999
"I'm not convinced it will be a bad year," he said. "We've had a
number of droughts in the past 13 years, and as long as we get that
nice cool-down period, starch levels have been adequate to produce
good color."

But if it stays warm through the first half of October (i.e. around
now), all bets on a long colorful fall are off. The trees get confused
by the heat and try to stay green longer to capture the longer growing
season.

So, bottom line -- it's too early to say - if it cools down for a week
around now you could still see an extended period of colour, but if it
is warm the trees could stay green to take advantage, then go quickly
once the temperature eventually falls
 
Willie


Prof. Abrams quote from this year in 
Drought Endangering Foliage display
http://aginfo.psu.edu/News/september02/drought.html

Google search terms
drought "leaf fall"

thanks for the fun answer~!  though i have a degree in biology, i dont
know much about plants.  i guess i will have to wait another week or
two!

as of last last saturday (2 sats ago), the weather was as warm as 80+
degrees.  and sunny.  and no rain.  but this weekend, its cooled down
considerably, with lows expected in the low 60s and it has been
drizzly, nippy and chilly.  promising!  :-)