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| Photo: Pedro Valente Lima |
Nature keeps amazing us and thats why some like to dedicate their whole lives studying it. It always has something to tell. What can we know about tree rings, though?
As we grow, years go by and we usually celebrate our birthday. Counting our age was never really a problem, but what about counting the age of a tree? Some have been around for thousands of years, but we can't really tell its age just by looking at most of them.
For centuries, even since the greeks, humans have tried to reach to an accurate age-measuring operation. In the early 20th century, the astronomer A.E. Douglass turned out with a discovery: tree rings have a correlation with its growth rate. Coming up with such a conclusion, he's the founder of dendrochronology - the scientific method of dating trees age - and of the Laboratory of Tree-Ring Research, in the University of Arizona, in the United States. But how does it work then?
Well, you don't need to ace rocket science to understand its simple method. The process is actually based on the rings presented by a tree. It can be from a branch, but the most accurate one is from the trunk, since it's the closest to the tree's birth. The counting is simple: the large and lighter rings are a sign of growing, on Spring, while the darkest and thinner ones correspond to a later time of the year, when the climate changes decrease its growth rate.
This method can only be tested on temperate climate areas of the world, where there's a clear difference among seasons. On areas near the Equator, for example, the counting is more difficult, as the tree rings can't really form a clear separation.
This is not the only thing these rings can tell, though. According to the rings size, one can determine the climate conditions it grew with and even compare it to trees from other areas. This can help when studying climate changes from different time and spaces, for example.
The difference between the center and the outer rings can also give us a perception of the live and dead tree cells. As you can see in this case, the dark area is actually the sum of dead tree cells, while the outer light rings represent the living cells.
There are also some patterns that can be easily identified when it comes to the tree's position. Normally, because of gravity, some trees tend to bend. As to fight this adversity, trees grow larger rings on the opposite direction of the one gravity is pulling to, forming thinner rings on the lower side.
This technique requires that you chop off a piece of tree? Normally, but there are other methods. You can either use an increment borer to drill into the center of the tree and get a small cylindric sample or you can observe other details, such as counting the tree's whorls.
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| Photo: leakstev.blogspot.pt/ |
These methods are not as effective, but won't recquire any tree chopping.
If you still want to learn more about it, here's a video summing up the essential:
If you still want to learn more about it, here's a video summing up the essential:
Author: Pedro Valente Lima
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