ul, not quite ready for turning off the air condtioner just yet - warm temps today - although there's a great mountain breeze clearing the dust from the porch.
What causes leaves to change color in the first place? Where does the color come from? Does the change have a practical purpose in nature's scheme of things? And why are the colors spectacular one year, but in another year just so-so?
Essentially, leaf colors begin to change because chlorophyll--a substance that makes them green--begins to diminish as a result of shorter days and cooler weather. As daylight shortens, the growth system in many trees begins to shut down. Tiny cells at the base of each leaf, known as the abscission layer, begin to dry out, chlorophyll dissipates and the photosynthesis process comes to a halt.
The colors that now begin to emerge are actually present in the leaves all year long; they are pigments masked by the chlorophyll during the warmer months. The yellows of such species as birch, aspen and hickory are caused by carotene, the same pigment that gives color to corn, carrots and egg yolks. The autumn reds and maroons in sugar maples, sumac and other species derive from the pigment anthocyanin, formed from sugar compounds stored in the leaves. This chemical's effect on color depends on the acidity or alkalinity of the tree. Red maples, which are more acidic, turn red; ash trees, being alkaline, become purplish.
While scientists understand what causes the leaves to change color, they know virtually nothing about why they change. What role does this phenomenon play in nature's broad scheme of things? The answer may be none at all. In his book Leaves: Their Amazing Lives and Strange Behavior, researcher James Poling writes: "This is both surprising and puzzling, since nature seldom wastes energy to no purpose. Yet as far as botanists can determine, the chemical energy that goes into the painting of a leaf is of no benefit at all to the plant. The colors seem merely to herald the end of a leaf's life cycle."
Whatever the reasons, the leafs are spectacular for humans to observe, and also great for the eco-system
That is all very interesting Stradee - While I agree with Poling's assessment that nature seldom wastes energy - I think the wise men must look at the phenomenon from the 'other' standpoint - ie., that the colors are not purposely made by the plants - but, are a consequence or side effect of another aspect of their survival - ie., going into an altered state of existence in order to survive the winter months.
There are animals of course who love to waste energy - OTTERS and such...................Oh, and as we have recently seen - PANDAS.....................They all love to play.....
You and your 299 friends have supported 2,571,074.0 square feet!
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1 Aktbird57 .. 1583 59.021 acres
59 acres- not bad!!
I didn't know that:
ABC News: Autumnal Foliage Can Be Pretty Tree-Killers (10/19/2005)
That maple tree in your front yard may be magnificent this time of year, cloaked in the colorful robes of splendor that herald the transition from one season to the next, but you might want to give it even more respect. It could be a killer.
Researchers at New York's Colgate University have found evidence that the brilliant red hues of autumn aren't just there for our personal enjoyment. They're engaged in a kind of chemical warfare, releasing poisons that could kill off the competition.
Thus maple trees, and probably some other species that turn crimson in the fall, join a growing list of plants that don't just beat around the bush when other plants start intruding into their space. They kill them off. Scientists call it "allelopathy."
For years scientists have known that black walnut trees are lethal when it comes to protecting their turf. And more recently, the mighty chestnut tree that once blanketed the Appalachians has come under suspicion. But the maple tree adds a surprising twist. How could anything that lovely be deadly?
Caught Red-Leafed
It all began when Colgate biology professor Frank Frey and a former student, Maggie Eldridge, started looking into a peculiarity involving plants that turn red in the fall. The predominant colors of autumn break out when chlorophyll in the leaves breaks down and exposes remaining pigments, which are often yellow or orange.
But it takes a different process to produce red. That isn't a pigment that is left over when everything else is gone. Instead, it's produced in the fall, at the very time when the tree is struggling to cope with the energy demands of a changing and challenging season.
Why, Frey and Eldridge wondered, did the maple go to all that trouble at a time when it needed its metabolic energy for other purposes, like stimulating the growth of its root system?
So they collected chemical extracts from red and green maple leaves and yellow and green beech leaves and poured it over lettuce seeds. Some previous research had shown that wood extracts from red maple and red cedar inhibited the growth of lettuce.
But Frey and Eldridge found that red maple is the clear winner. It "dramatically reduced germination and growth compared to all other treatments," they say in a study that is soon to be published.
"When scarlet-tinted autumn leaves are dropped in the fall, it appears that anthocyanins (molecules that produce the red color) leach from the leaves into the soil and protect seedlings and saplings from interspecific competition the following spring," Frey says. In other words, no one but maples allowed.
All of this has a practical purpose. As Frey notes, other research shows that anthocyanins may inhibit the growth of some cancer cells in vertebrates, so eventually there may be a medicinal application. Other researchers see this kind of chemical warfare as a possible pathway to better weed control.
And it has opened a surprising window on just how ruthless some species may be when it comes to protecting their turf.
Combative Chestnuts
For decades scientists thought that the dominance of the chestnut tree in the Appalachian forests was due to its own personal majesty. It was a fast grower, rapidly shading any competing trees. It resisted rot and fire, and was happy in poor soil.
But along comes ecologist Barry Clinton of the U.S. Forest Service's Southern Research Station in North Carolina with some shocking news: The mighty chestnut, it turns out, was engaged in a little skullduggery.
Clinton and colleagues at Clemson University and the University of North Carolina at Chapel Hill tested the effects of fallen chestnut leaves on five tree species that competed for the same space.
They found that an extract from the leaves inhibited germination of the competing trees -- particularly eastern hemlock, a major species along mountain streams in the Appalachians. It also curtailed the growth of a native rhododendron.
But that colorful shrub may have won out in the end. The chestnuts were wiped out by a blight years ago, and since that time the rhododendrons have flourished.
The rapid encroachment of this shrub "may be largely due to the end of the tree's allopathic influence," Clinton says.
Other Botanical Killers
Other trees known to poison their competitors include sycamore, eucalyptus, hackberry, and the notorious black walnut.
Black walnut produces the chemical juglone, which can spell trouble for a wide variety of trees and plants.
Researchers have found, for example, that black walnut can inhibit corn production even if the trees are some distance from corn stalks.
However, lest we be accused of slamming only deciduous trees, it should be noted that even pine trees are not without their chemical weapons.
Pine needles decompose after falling to the ground, releasing an acid that leaches into the soil. That keeps almost anything from sprouting near the tree's roots.
And lastly, the next time someone tells you how broccoli is good for you, tell them that broccoli plants leave a residue in the soil that makes it difficult for some other crops to follow.
It may be a super-food, but it's not without its faults.
ul, that is absolutely fascinating.......I continue to learn new stuff. Thanks.
all clicked
An altered state, yep. So why don't the leafs just fall off the tree, sensibly, instead of the georgous color light-the-entire-yard-in-hues-of-gold n' orange- spectacular?
Because they can.
Wow, ul! Very facinating article! Leafs are also a good source of nourishment for small insects, and a great natrual mulch - but i had no idea the trees mentioned in the article were so territorial! Amazing.
ehBeth, cute avatar!
thanks Stradee - I think the name tag over my mouth is evocative of something
silence, perhaps?
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You and your 299 friends have supported 2,572,385.2 square feet!
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Rainforest habitat supported: 2,386,549.3 square feet.
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1 Aktbird57 .. 1584 59.050 acres
MmmmHmmmmm, I noticed the new avatar the first day you posted it........You rook Maavelous..!!!
Hey, Wildclickers - - - we will have saved SIXTY ACRES by the weekend!!!
Enviornmental News reagarding the Roadless Rule!
A federal judge in California reinstated Clinton-era protections against logging and mining in forests, invalidating the administrations substitute policy.
Now keep fingers, eyes, and toes crossed for the Tongas, not included in the ruling because a second set of legal opinions determine their use. However, with the Roadless Rule reinstated, environmental and endangered speices studies for alternative methods of operation will again be mandatory.
http://www.nytimes.com/2006/09/21/washington/21roads.html?ex=1159502400&en=2e2c5da08835d4e6&ei=5070&emc=eta1
Minding the fingers, eyes and toes, Stradee........ grin
That all sounds great - I'm wondering if Hillary will decide to run for president. If so, I for one will vote for her.
all clicked.
Dan, you're a gem!
Hillary and Bill, hand n' hand, walking through the front door of the White House - again!
There is a God!
More good news!
The enviornment - celebrating the Roadless Rule court decision, and voila!
Recall one of the questions at Amigos trivia thread was: What is the world's tallest tree? A: The Statosphere Giant
Check out "Hyperian"!
http://www.sfgate.com/cgi-bin/article.cgi?file=/c/a/2006/09/07/MNGQRL0TDV1.DTL
You and your 299 friends have supported 2,574,000.7 square feet!
Marine Wetlands habitat supported: 130,333.2 square feet.
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American Prairie habitat supported: 55,713.5 square feet.
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Rainforest habitat supported: 2,387,954.1 square feet.
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clicked for me and devriesj
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1 Aktbird57 .. 1585 59.089 acres
Yeah, Stradee, I was one of the "MAJORITY" who actually voted for GORE in yr2000 .......!!! Also, the "NEXT" time I voted for John Kerry ..... I still think the SCHRUB family will go "DOWN" in history dramatically......
:wink:
Yep, with November drawing nearer... and the repubs spending a billion dollars for ads...drama we don't need!
History will have a field day explaining the conclusion to the presidents illustrious career...
:wink:
I think I was off a little re the sixty acres - however, I didn't say WHICH weekend - -
all clicked.
oops, Dan and Merry - wasn't paying attention.
Way to much politics to deal with lately, but the following is serious and i'd like your opinions. Thanks.
Just received an e mail from The Nation with the following article:
"War Signals" By Dave Lindorff, The Nation
As reports circulate of a sharp debate within the White House over possible US military action against Iran and its nuclear enrichment facilities, The Nation has learned that the Bush Administration and the Pentagon have issued orders for a major "strike group" of ships, including the nuclear aircraft carrier Eisenhower as well as a cruiser, destroyer, frigate, submarine escort and supply ship, to head for the Persian Gulf, just off Iran's western coast. This information follows a report in the current issue of Time magazine, both online and in print, that a group of ships capable of mining harbors has received orders to be ready to sail for the Persian Gulf by October 1.
http://www.thenation.com/doc/20061009/lindorff
clicked for me and dev while enjoying a giant bowl of oatmeal and some nice rye toast ... it's cooling off outside and I'm happy ... still no socks though
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You and your 299 friends have supported 2,575,663.1 square feet!
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1 Aktbird57 .. 1586 59.126 acres
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New thread time.
Anyone going to call dibs?
