How do botanists know the exact age of a tree?

In climates that regularly have a season of growth and a season of rest each year, trees grow with a series of ‘annual rings’, which can be seen in a cross-section of the trunk. In some trees, these rings are marked, and we have only to count them to have a good idea of the tree’s age.

Sometimes, however, the count may not tell the entire story. So long as the tree goes on living healthily, a fresh ring will be formed each year, but the growth of a tree may be interrupted and begin again during the same season, and then two false rings appear. The false rings are much thinner than the true rings and do not always extend right around the tree. A drought or a severe attack by caterpillars or other insects may lead to interrupted growth and give rise to the false rings. The tree forms both true and false rings by adding new wood around the trunk just beneath the bark.

Botanists can distinguish between one year’s growth and the next because the wood added in the earlier part of the year is different from the wood added later in the summer. In the spring, when growth begins and fresh leaves and twigs are put out, much water is needed in the crown of the tree to supply these new, springtime cells with thin walls and wide openings so that the water can rise rapidly. In summer, however, when there is less demand for water, the cells formed are thick-walled and have small openings. That explains why the summer wood in each year’s growth is heavier and stronger than the spring wood.

This is a valuable practice that helps determine, not only the growth of trees but also the rate of growth of different kinds of trees. It helps to determine the factors that slowed and accelerated the growth of the tree, from the annual rings.

Here are some books that can give you valuable information regarding the growth of trees and how you can tell their age and determiners of growth:

Where to Buy
Forest Measurements, Fifth Edition
Forest Mensuration
Nature's Temples: The Complex World of Old-Growth Forests


Forest Measurements

Wood or timber is a fascinating thing. It can be crafted and made into lovely art as per desire. This book emphasizes the value of measurements. The age and quality of standing trees, measurement of timber, and wood products. It lays special emphasis on measuring the course of growth of standing trees and therefore helps plan constructions or finding a good use for the timber.

This one is the fifth edition of the book, which is written by Thomas Eugene Avery and Harold E. Burkhart.

Forest Mensuration

This one is the 5th edition of Forest mensuration. It is a complete guide that integrates all concepts of forest mensuration. It takes into account all processes of forest growth or recession and regeneration. It signifies tools and equipment for measuring the growth of forests. The author takes into account modern technology, also elaborating on the use of computer programs and the like to store the data and use it further for statistics.

Nature’s Temples

Nature’s Temples is an appreciation of all old-growth forests. The forests that have been there for hundreds of years. The author Joan Maloof appeals emphatically to let the world realize the importance of these old-standing growths. He describes the birth of forests and their history very evocatively. He paints a beautiful portrait of words about these majestic trees and the forms of life they sustain. In between this delicate piece of art, light is thrown upon the scientific facts and the concerns faced by these old and wondrous trees on the face of the Earth.