Tree -rings

        Can you believe that you may count the age of a tree.Even you may tell about the past climatic conditions just by studying a timber or a tree trunk ! Yes, you can do it. This is a branch of Science and termed as Dendrochronology.                                                     
            Andrew E. Douglass founded the technique of dating events by studying the pattern of growth rings in tree trunks in the late 1800s and early 1900s and established the Laboratory of Tree-Ring Research at the University of Arizona.     

                                           In most of the temperate trees and shrubs annual-rings are formed due to the secondary growth.A year may be divided into Spring and Winter and the wood formed in spring is called as "early wood" and that of the winter is "late wood".                     

       The spring wood is light in colour as the wood formed possess thin walled element and vessels with large lumen,hence light banded. On the other hand winter wood contains thick walled vessels with narrow lumen ,hence dark banded.The reason behind that is in spring there is a huge amount of moisture in the environment , whereas  there is less moisture in winters.These two bands together constitute an annual ring or a growth ring.So,the dating and study of the annual-rings in trees is known  as Dendrochronology.