20 Trees, Stars, and Birds 



bast fibers and are very abundant in some trees (page 

 59). Why do beetles and borers often feed on this 

 layer of tissues in a tree ? Will the roots of a tree die 

 if the bark on the trunk is cut all around it? Why? 



Telling the age of trees. On the top of a stump or the 

 end of a log you can often count the rings. To deter- 

 mine the age of the tree, do you count the springwood 

 and summerwood as representing two years or one ? In 

 exceptional cases, as when a drought divides the growing 

 season into two parts, two fairly distinct rings may form 

 in one year, but generally you can tell the age of a tree 

 quite closely by counting the number of rings. If the 

 section whose rings you are counting was not made near 

 the ground, you must make allowance for the time it 

 took for the tree to attain that height. 



Are the annual rings all of equal thickness in the same 

 stump? Are there places where you can count twice 

 as many to the inch as in other places ? .What may have 

 caused the tree to grow more in some years than in 

 others? Can you think of a way to test the correctness 

 of your explanation? How could you find out, without 

 asking any one to tell you and without reading about it, 

 whether a certain kind of tree grows fast or slowly ? On 

 the stump or other section of a tree or of a branch, is 

 the same ring uniform in thickness all the way round? 

 How do you account for this? Frequently disputes 

 about the ownership of land have been decided by the 

 age of trees and by counting the rings to find how many 

 years ago a certain mark was placed on a tree by a 

 surveyor. 



You will find it interesting to fix as nearly as possible 



