Question
Hi Jim,

Not sure if this would fall under your area of expertise or not, but I have always had an interest in trees and have a few questions on how trees can be dated.

I have a few very large oak trees growing in the woods behind my house that each measure about 20 feet in circumferance.  Is it possible to estimate about how old these trees are given that they probably have had good growing conditions, although somewhat severe winters here in the northeast U.S., and have no visible signs of having their growth stunted by disease or lightning strikes?

Also, do you know of any books out there that document and illustrate large trees growing through-out the world?

Again, not sure if this is your area or not, but any help at all would be appreciated!

Thanks,

Edward

Answer
Aging of trees is done with an instrument called an increment borer. It is a hollow drill that is bored into the tree about half way through the trunk. The tree lays down cells each year and the core that is extracted from the borer is marked with these lines of annual cells--counting them will give the age of the tree. A large tree will need a large increment borer to each the center of the trunk. here is a web link that describes with pictures this process.
http://www.fw.vt.edu/dendro/Forsite/incre.htm

If you will call your local office of the State Forestry Agency and ask one of their Forester to come age the tree for you I am sure they can do this .
Here is one book called Remarkable Trees of the World
http://www.powells.com/cgi-bin/biblio?inkey=72-0393049116-0