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Author Topic: Are we able to age a tree without chopping it down or drilling a hole into it ?  (Read 7474 times)

Offline neilep

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Hi Peeps,

Happy Day !

Well, the title says it all really...can we tell the age of a tree by using non invasive techniques ?


 

paul.fr

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I suppose there could be a few ways of doing this.

1. there may be written records of when the tree was planted, if it was planted to commemorate a person or event, say.

2. I would think you can carbondate a tree

3. By measuring the growth rate, im not too sure how this is done but if you know the tree grows at a given rate per year, then you could simply calculate the tree's present height and work out how many years it would have taken to grow to that height based on one years growth.
 

Offline DoctorBeaver

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*waits for Stuart*
 

paul.fr

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*waits for Stuart*

what are you trying to say  [?]
 

another_someone

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*waits for Stuart*

what are you trying to say  [?]

Stuart works in forestry (cannot recollect his role right now, something to do with the European forestry commission, or something, if I recollect - it is somewhere mentioned on the site if you want to search for it).
 

another_someone

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You cannot carbon date a living organism because carbon dating merely dates an organism to the date when it was last alive, so an organism that is still living will have zero carbon date - you date the death of the organism, not its birth.
 

another_someone

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I suppose if you want to pay nots of money, you could use MRI (or maybe even a CAT scan) to show the tree rings in a non-invasive way.

Drilling a hole into a tree is the common way to do it for living trees, and the tree will normally heal over - so it is invasive, but should not cause lasting harm to the tree.
 

paul.fr

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*waits for Stuart*

what are you trying to say  [?]

Stuart works in forestry (cannot recollect his role right now, something to do with the European forestry commission, or something, if I recollect - it is somewhere mentioned on the site if you want to search for it).

Yes, i knew that. It was a tongue in cheek reply.


You cannot carbon date a living organism because carbon dating merely dates an organism to the date when it was last alive, so an organism that is still living will have zero carbon date - you date the death of the organism, not its birth.

I thought they had carbon dated a living Methuselah Tree !
 

another_someone

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You cannot carbon date a living organism because carbon dating merely dates an organism to the date when it was last alive, so an organism that is still living will have zero carbon date - you date the death of the organism, not its birth.

I thought they had carbon dated a living Methuselah Tree !

http://www.pbs.org/wgbh/nova/methuselah/resources.html
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Dr. Edmund Schulman, who discovered the Methuselah Tree in the 1950s, began his career in dendrochronology in 1932 at the University of Arizona's Laboratory of Tree Ring Research.

http://en.wikipedia.org/wiki/Bristlecone_pine
Quote
Currently, the oldest (acknowledged) living organism known is an individual of Pinus longaeva nicknamed "Methuselah" (after Methuselah, the longest-lived person in the Bible), located in the Ancient Bristlecone Pine Forest in the White Mountains of eastern California, and measured by core samples to be about 4,700 years old.

http://english.sdaglobal.org/research/c14.htm
Quote
Carbon Dating is a controversial dating technique. The method is based on the rate of decay of the radioactive carbon isotope, Carbon-14, which is formed in the upper atmosphere through the effect of cosmic ray neutrons upon Nitrogen-14. The Carbon-14 is rapidly oxidized and enters the earth's organic life through photosynthesis (plants) and the food chain (animals). Carbon-14 also enters the earth's oceans in an atmospheric exchange and as dissolved carbonate. Plants and animals, which utilize carbon in organic functions and food chains, absorb Carbon-14 during their lifetimes. The assumption is that the earth-bound carbon exists in equilibrium with the Carbon-14 in the atmosphere, which means that the number of Carbon-14 atoms and non-radioactive carbon atoms stays approximately the same over time. As soon as a plant or animal dies, it ceases its carbon intake. Thereafter, there is no replenishment of radioactive Carbon-14, only decay. In 1949, a team of scientists led by Willard Libby of the University of Chicago discovered that this decay occurs at a constant rate. They found that after 5,568 years, half the Carbon-14 in a dead sample will decay, and after another 5,568 years, half of that remaining Carbon-14 will decay, and so on. Thus, the "half-life" for Carbon-14 was measured by Libby and his team at 5,568?0 years. After ten half-lives, there is a miniscule amount of radioactive carbon left in a sample, which means that the limit of the Carbon Dating method is reached at between 50,000 and 60,000 years.

It may be argued that some old trees may contain much dead wood, in which case you may be able to carbon date when that wood died.

On the other hand, if a tree is still living, then tree rings are more accurate than carbon dating, since you can identify each year of growth accurately, rather than relying exponential radioactive decay, and trying to approximate from that.
 

Offline eric l

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This reminds me of some species of the willow tree, that end up by being hollowed out as the dead wood inside is attacked by worms and insects.  I know some specimens measuring over 3 m around (making a diameter of about 1 m) that have only about 7 cm of living wood at the outside, and are hollow in the middle.  Impossible to work with tree rings and no wood from the centre for carbon dating.
 

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Offline DoctorBeaver

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Just count the number of candles on its birthday cake!
 

Offline dentstudent

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Currently, there is no fast, accurate method for this. There’s an accurate one, but it’s not fast!

There are methods of determining tree-rings in a stem using something similar to x-rays, as was previously mentioned. However, this technique is used in sawmills to detect knots (the hard bit inside the stem where a branch has been enveloped by the tree's growth), and other bodies within the stem that may cause problems to the saw. Of course, there is one obvious problem with this in that the tree is already felled. There are instruments for the same process on living trees, but is expensive, time consuming and can be rather limited. So yes it is possible, but is still quite developmental.

The current (non-invasive) methods are:

Historical documentation 1: all forests that are growing on a rotation basis (a bit like a crop - plant, grow, reap) have planting dates noted. Once you start using forestry which operates on a diameter felling target (ie, when a tree reaches 60 cm diameter it is felled) which is very common in Europe, the age of the tree is not important, and is not noted in any inventories.

Historical documentation 2: Deer parks and so on that feature in old maps may show the position of individual trees. Also, inventories kept by the management may also do this, but are generally only indicative, rather than definite.

Diameter growth: There are papers which model the age of the tree based on diameter growth, for example, with oak and yew. These techniques are again best-guesses, and cannot be used to provide a definitive age, ie. they cannot say “this tree was planted in 1837, and is therefore 170 years old”.

The problems associated with using dendrometrics (height, diameter etc) in the ageing of trees they are not constant. There are many inputs into the growth and development of trees that can individually affect height and diameter. The most common influences are light, water, soil depth and nutrition, topological exposure and competition. An example of the influence of one of these would be for Silver fir in the Black Forest. It is capable of surviving for many decades as a small tree underneath a canopy, waiting for an opening. This “quazi-stationary period” means that it may appear to be a sapling of 2 or 3 metres height, but could actually be 100 years old. When the canopy becomes open through the removal of a neighbouring tree, the decrease in competition of the growth inputs means that the tree is “released” and can readily put on both height and diameter growth. Therefore, the use of simple height and diameter measurements can be very misleading in the estimation of age.
The coring of trees is the most commonly used, but has its own problems. It presents an entrance for pathogens; there is no guarantee that you will actually obtain a reading of all the rings because trees do not generally grow rings evenly; there may not actually be a middle.
 

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