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Fall Colors, Why do Leaves Change?
October 15, 2012
My apologies to all of my Canadian friends for not wishing you a Blessed Thanksgiving last week.
I hope all went well.
And the winner of ArtPrize is........
'Elephants' By Adonna Khare.
I figured she would be the Grand Prize winner.
ArtPrize is a 17 day event with artists from around the world and is pretty much a popularity contest.
Yes, everyone becomes a critic, as the winner is based on popular vote.
The four years of ArtPrize, popular vote has in my opinion, has been right on.
What a wet weekend.
Even some Thunder Boomers thrown in.
The rain is very welcome in the Great Lakes area.
Since this past spring, Lakes Michigan and Huron are down a good 12" of water.
That my friend, is a serious amount of water.
All five Big Lakes are down.
We saw our first snow flakes for a brief moment on Wednesday.
I know some of you have already had accumulations, so it is no big deal, yet it is always a "Go Away" moment when I see the white stuff for the first time.
Even it it was only a few flakes.
Fall clean up continues.
I still haven't had a killing frost or freeze.
Yes, I still have annuals in bloom and a couple of tomato plants (green tomatoes, yum).
Remember, not to put any fungus or diseased foliage into your compost bins or to winter over.
Cooties winter over and there is no guarantee that a compost
It is best to simply trash this material.
Fall is always the best time to till or dig your gardens.
(Downtown Boyne City.)
You can work in compost, manure, shredded leaves, etc.
By doing so in the fall, the organic matter is already decomposing and breaking down with the soil.
Dirt clumps slowly break down with fall rains and spring snow melt.
When spring rolls around, your soil is fresh, full of nutrients and oxygen.
If you wait till spring to dig, you are several months behind.
Not only is your organic matter still in one heap, when you walk or dig your gardens, you are packing down the soil even more.
Besides, this time of year you can work at your own pace, not a hurried pace that spring and planting may dictate.
It starts with a whisper.
Maybe a single branch.
Possibly a lone tree along the street or in a field.
Slowly a crescendo of colors builds to a fiery pitch, where the hills and valleys scream out.
Look At Me........
Here I am..........
Timing can be everything.
It doesn't last.
This past week, we enjoyed a short trip to Northern Michigan on what has become an annual color tour for us.
A visit to some of the small towns and villages that dot the landscape.
A barn in the distance, or a pile of rubble that was once a homestead (pictured below).
We stopped off at a Farmers Market and paid a small fortune for some farm fresh apples.
Michigan's apple crop is a mere 10% of what is should be, due to the strange weather this past spring.
Still, apples help define autumn.
All worthy of a moment.
Look around while your taking pictures, you may discover you too are being watched.
(The doe was less than 50 feet from me, as she watched in silence.)
You may have moments where words cannot describe, and pictures cannot capture the true beauty.
Colors so vivid that even a cloudy day could only mute them so much.
Karen, Yolanda and I caught but a glimpse of .........
"A Touch of the Master's Hand".
In awe and cognizant of His presence.
Still, Timing is Key.
Hop in the car or go for a walk.
Catch the show before it passes for the year.
If you don't know by now, this weeks letter is on Tree and why they change colors.
For some of you, this is a refresher course as I haven't written about this for 3 or 4 years.
Still, for new readers this is a chance to possibly glean a morsel of knowledge.
Days continue to grow shorter and cooler.
Gardens are pretty well done growing for most of us
Fall clean up continues and of course, the colors that fall offers us.
Like the grand Grand Finally of a fireworks display, Nature offers us one last hurrah.
The end of another wonderful growing season.
A reminder to us all, that God is indeed in control.
(You don't think all of these wonderful orchestrated events just happens do you?)
As a child, I didn't care why they changed colors and parents and teachers would give a half correct answers.
As a Naturalist, I continue to grow more curious as to why certain things happen.
Fortunately, several have gone before us to study and research things.
Researchers and schools with all sorts of cool equipment and labs where they can research why leaves change colors and so on.
For years, scientists have worked to understand the changes that happen to trees and shrubs in the autumn.
Although we don't know all the details, we do know enough to explain the basics and help you to enjoy more fully ' Nature's ' multicolored autumn farewell.
Three factors influence autumn leaf color.
Leaf pigments, length of night, and weather, but not quite in the way we think.
The timing of color change and leaf fall are primarily regulated by the calendar, that is, the increasing length of night.
None of the other environmental influences...........temperature, rainfall, food supply, and so on-are as unvarying as the steadily increasing length of night during autumn.
As days grow shorter, and nights grow longer and cooler, biochemical processes in the leaf begin to paint the landscape with Autumn's palette.
Why Do Leaves Change?
Leaves are nature's food factories.
Plants take water and oxygen from the ground through their roots.
They take a gas called carbon dioxide from the air.
Plants then use sunlight to turn water and carbon dioxide into glucose.
Plants use glucose ( a kind of sugar) as food for energy and as a building block for growing.
The way plants turn water and carbon dioxide into sugar is called "Photosynthesis."
That "word" we all learned about at one time or another.
It means "putting together with light."
A chemical called chlorophyll helps make "Photosynthesis" happen.
You know that Chlorophyll is what gives plants their green color.
Where do the Autumn Colors Come From?
A color palette needs pigments, and there are three types that are involved in Autumn color.
The quiet green of summer foliage is transformed into the vivid autumn reds, oranges, yellows, golds, and browns before the leaves fall off the trees.
On years like this one, the colors are truly breathtaking.
Chlorophyll, which gives leaves their basic green color.
It is necessary for photosynthesis, the chemical reaction that enables plants to use sunlight to manufacture sugars for their food.
Trees in the temperate zones store these sugars for their winter dormant period.
Carotenoids, which produce yellow, orange, and brown colors in such things as corn, carrots, and daffodils, as well as rutabagas, buttercups, and bananas.
Anthocyanins, which give color to such familiar things as cranberries, red apples, concord grapes, blueberries, cherries, strawberries, and plums.
They are water soluble and appear in the watery liquid of leaf cells.
Both chlorophyll and carotenoids are present in the chloroplasts of leaf cells throughout the growing season.
Most anthocyanins are produced in the autumn, in response to bright light and excess plant sugars within leaf cells.
During the growing season, chlorophyll is continually being produced and broken down and leaves appear green.
Phosphate is at a high level.
Phosphate has a vital role in the breakdown of the sugars manufactured by chlorophyll.
But in the fall, phosphate, along with the other chemicals and nutrients, moves out of the leaf into the stem of the plant.
When this happens, the sugar-breakdown process changes, leading to the production of anthocyanin pigments.
As night length increases in the autumn, chlorophyll production slows down and then stops and eventually all the chlorophyll is destroyed.
The brighter the light during this period, the greater the production of anthocyanins and the more brilliant the resulting color display that we see.
When the days of autumn are bright and cool, and the nights are chilly but not freezing, the brightest colorations usually develop.
The carotenoids and anthocyanins that are present in the leaf are then unmasked and show their colors.
The carotenoids occur, along with the chlorophyll pigments, in tiny structures called "plastids" within the cells of leaves.
Sometimes they are in such abundance in the leaf that they give a plant a yellow-green color, even during the summer.
But usually we become aware of their presence for the first time in autumn, when the leaves begin to lose their chlorophyll.
Certain colors are characteristic of particular species.
Oaks turn red, brown, or russet;
Hickories turn golden bronze;
Ash species (those that are still alive) turn yellow or purple.
Aspen and yellow-poplar, are a golden yellow.
Dogwood turn purplish red;
Beech, light tan.
Sourwood and black Tupelo turn crimson.
Maples differ species by species-red maple turns brilliant scarlet.
Sugar maple, orange-red; and black maple, glowing yellow.
Striped maple becomes almost colorless.
Leaves of some species such as the elms simply shrivel up and fall, exhibiting little color other than drab brown.
Are you getting them idea here?
The timing of the color change also varies by species.
Sourwood in southern forests can become vividly colorful in late summer while all other species are still vigorously green.
Oaks put on their colors long after other species have already shed their leaves.
These differences in timing among species seem to be genetically inherited, for a particular species at the same latitude will show the same coloration in the cool temperatures of high mountain elevations at about the same time as it does in warmer lowlands.
How does weather affect autumn color?
The amount and brilliance of the colors that develop in any particular autumn season are related to weather conditions that occur before and during the time the chlorophyll in the leaves is dwindling.
The best places in the world for viewing fall colors is probably the Eastern United States and Michigan's western Upper Peninsula.
(Porcupine Pine Mountains with Lake Superior in the background)
This is because of the climate there, and the wide variety of deciduous trees.
The brightest colors are seen when late summer is dry, and autumn has bright sunny days and cool (low 40's Fahrenheit) nights.
Then trees make a lot of anthocyanin pigments.
A fall with cloudy days and warm nights brings drab colors. And an early frost quickly ends the colorful display.
Temperature and moisture are the main influences.
A succession of warm, sunny days and cool, crisp but not freezing nights seems to bring about the most spectacular color displays.
During these days, lots of sugars are produced in the leaf but the cool nights and the gradual closing of veins going into the leaf prevent these sugars from moving out.
These conditions-lots of sugar and lots of light-spur production of the brilliant anthocyanin pigments, which tint reds, purples, and crimson.
Because carotenoids are always present in leaves, the yellow and gold colors remain fairly constant from year to year.
The amount of moisture in the soil also affects autumn colors.
Like the weather, soil moisture varies greatly from year to year.
The countless combinations of these two highly variable factors assure that no two autumns can be exactly alike.
A late spring, or a severe summer drought, can delay the onset of fall color by a few weeks.
A warm period during fall can also lower the intensity of autumn colors.
A warm wet spring, favorable summer weather, and warm sunny fall days with cool nights should produce the most brilliant autumn colors.
What triggers leaf fall?
In early autumn, in response to the shortening days and declining intensity of sunlight, leaves begin the processes leading up to their fall.
In late summer the veins that carry fluids into and out of the leaf are gradually closed off as a layer of special cork cells forms at the base of each leaf.
As this cork layer develops, water and mineral intake
It is during this time that the chlorophyll begins to decrease.
Often the veins will still be green after the tissues between them have almost completely change color.
These clogged veins trap sugars in the leaf and promote production of anthocyanins.
Once this separation layer is complete and the connecting tissues are sealed off, the leaf is ready to fall.
What does all this do for the tree?
Winter is a certainty that all vegetation in the temperate zones must face each year.
Perennial plants, including trees, must have some sort of protection to survive freezing temperatures and other harsh wintertime influences.
Stems, twigs, and buds are equipped to survive extreme cold so that they can reawaken when spring heralds the start of another growing season.
Tender leaf tissues, however, would freeze in winter, so plants must either toughen up and protect their leaves or dispose of them.
'Evergreens' keep most of their leaves during the winter.
They have special leaves, resistant to cold and moisture loss.
Some, like pine and fir trees, have long thin needles.
Others, like holly, have broad leaves with tough, waxy surfaces.
On very cold, dry days, these leaves sometimes curl up to reduce their exposed surface.
Evergreens may continue to photosynthesize during the winter as long as they get enough water, but the reactions occur more slowly at colder temperatures.
It is important to keep your evergreens hydrated throughout winter if possible.
If that isn't possible, water them until the snow really flies.
A hydrated evergreen is more apt to survive a cold winter, especially one that has been planted in the past couple of years.
Their needle-like or scale-like foliage is covered with a heavy wax coating and the fluid inside their cells contains substances that resist freezing.
Thus the foliage of evergreens can safely withstand all but the severest winter conditions, such as those in the Arctic.
On some evergreens, needles and leaves may survive for a years but eventually fall because of old age.
The leaves of broad leaved plants, on the other hand, are tender and vulnerable to damage.
These leaves are typically broad and thin and are not protected by any thick coverings.
The fluid in cells of these leaves is usually a thin, watery sap that freezes readily.
This means that the cells could not survive winter where temperatures fall below freezing.
Tissues unable to over winter must be sealed off and shed to ensure the plant's continued survival.
Thus leaf fall precedes each winter in the temperate zones as sap flow slows and trees go into hibernation.
Here is a bit of information I thought you might like, that I read a couple of years ago.
The scarlet leaves of the maple tree are a particularly awe-inspiring attraction for hikers and paddlers on lakes and rivers during the fall season.
Research suggests that there is more to the crimson of the leaves than meets the eye.
Researchers at Colgate University in Hamilton, N.Y., report that the chemical responsible for the bright red color also acts as a competitive herbicide when it leaches into the ground.
The red helps to keep other like maples from growing and competing under or close to its self.
Another one of Nature's awesome wonders.
Summer's foliage changes colors and falls to the forest floor or we rake them and hopefully put them to good use.
Leaves are now food for many micro-organisms and offer food and protection for small mammals and insects.
Decaying leaves feed the trees and forest floor.
Insects offer food for birds and mammals.
Mammals become food fox, birds of prey, snakes etc.
The list goes on.
The circle of life goes on.
Many gardeners color coordinate the fall colors of trees and shrubs into their landscape.
You can add many of these fall colors in your wildlife landscape too.
Non-native burning bushes are pretty and offer protection and nest sights.
Native Viburnums are very colorful and offer food as well, some well into winter.
Serviceberries have brilliant fall colors.
What about native Dogwood and Sassafras trees.
There are so many native trees and shrubs that offer food, protection, a place to raise a family.
Natives also offer color and beauty for your pleasure as well.
This may not have been the science lesson you wanted or was looking for, but it is a part of nature and our backyards.
Here is one more tidbit.
Research shows and suggests that fall colors help birds with migration by finding food sources.
Learned and instinctive behaviors help birds to locate food by fall leaf coloration.
Certain shades of red or other colors mean certain fruits and berries.
An example would be:
Native shrubs and trees like Red chokeberry (Aronia arbutifolia) and Black chokeberry (Aronia melanocarpa) are good choices for naturalistic sites and can tolerate moist conditions.
The bright red fall color is matched by the plant’s bright red berries, guaranteed to attract migrating birds.
It works for hummingbirds, why not other birds?
Birds know that certain colors mean food.
Creating wildlife habitats and birdscaping your yard just got a bit more fun and interesting, didn't it?
How wondrous that nothing goes unnoticed or goes to waste in the natural world.
It's amazing how God's wonders that can take our breath away and blow our mind at the same time.
Well, it's time to fly for now.
Before I go, here is your positive thought for the week.
“Patience is waiting.
Not passively waiting.
That is laziness.
But to keep going when the going is hard and slow
- that is patience.”
Another one of my favorite verses.
But those who hope in the Lord
Isaiah 40:31 (NIV)
"Treat the earth well:
It was not given to you by your parents,
It was loaned to you by your children.
We do not inherit the Earth from our
Ancestors, we borrow it from our Children."
Ancient Indian Proverb
Your friend indeed,
Better yet, have them sign up so they can receive their own letters.
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