MemberMarch 25, 2015 at 1:05 pm
Many think about leaves in the fall, but what about spring when trees come out of dormancy and have to bud out all those leaves. As for the number, I have seen estimates as high as 7 million and as low as 20K for a mature tree. My guess it is probably around 200K on a large mature tree. Do you know a good source to measure the number of leaves. My favorite was from Georgia Gardner Walter Reeves for the simplicity. Below are some sources. Do you have a better source?
The photograph is from photographer Kathryn Kolb. Used with her permission.
Forester Dr. Kim Coder says that a very rough estimate can be gotten by measuring the area (in square feet) beneath the crown of a tree and multiplying by 4. This gives you the estimated total leaf surface area of the tree in square feet. Next, estimate how many individual leaves it would take to cover one square foot. Multiply that result by the total leaf surface, which gives you an approximation of the number of leaves on that tree.
Example: the sweetgum in my front yard has a crown 30 feet wide. The area under it is approximately 700 square feet. Multiplied by 4, I see that the tree has 2,800 square feet of leaf area. Iâ€™ll guess that 8 sweetgum leaves would cover one square foot. Multiplying 8 times 2,800 reveals that the tree has close to 22,400 leaves.
A big oak tree might have a crown 50 feet wide. In that case, one could estimate the tree has 63,000 leaves. Necessarily, this is a rough guess because the crown shape of the tree is not taken into account (some trees are dome-shaped, some are tall and narrow, etc). However, this quick math should give you something to think about as you rake the last of the leaves from your lawn this week.
How many leaves does a tree have?
"It depends on the tree's species and age, but a mature, healthy tree
can have 200,000 leaves. During 60 years of life, such a tree would
grow and shed 3,600 pounds of leaves, returning about 70% of their
nutrients to the soil."
Most trees lose their leaves each fall, but some keep them over
winter. Why is that?
"In spring, new leaves and twigs grow out together and are firmly
attached. In fall, a specialized layer of "abscission" cells form
between each leaf and twig, cutting off water to the leaf and killing
it. Then the abscission cells die and the leaf falls off. In young oak
trees, however, for reasons that are unclear, abscission cells form
but do not complete their work. Therefore, oak leaves often stay
connected to the twig until pushed off by new leaf and twig growth in
Quercus robur - English Oak
Pedunculate-Oak Quercus robur (Fagaceae)
"When young, it keeps its leaves through the winter and can be a
useful addition to a hedge."
Interesting Fact - How much do the fallen oak leaves actually weigh
once they dry out?
Watershed Quiz Answer to Question 3
"The correct answer is A. When fallen leaves dry out, they don?t weigh
very much. Researchers have found that 25,000 dry, oak leaves weigh
less than 70 pounds. This is about as much as the average Chesapeake
Bay retriever weighs."
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