Question

The age of a tree can be estimated by
A. Its height and girth.
B. Biomass.
C. Number of annual rings.
D. Diameter of its heartwood.

Answer 1

The horizontal cross-sections of the trunk of a tree can be used to reveal the growth of the tree. The growth in vascular cambium which is a layer of cells near the bark which is a lateral meristem makes circles each year. These are the markings that are used by botanists to calculate the age of the tree.

Complete answer: The vascular cambium tissue that lies between the vascular tissues of a plant namely phloem and xylem causes secondary growth in plants. The secondary growth is responsible for wood formation that makes the bark of the tree. Further growth in vascular cambium forms circular rings called growth rings or annual rings. The growth in diameter is caused due to growth in secondary tissues of plants. This results in the formation of annual rings. These are visible ring structures seen in the horizontal cross-section of the bark of the trees. Each growth season makes one ring. One ring marks the passage of one year.
Trees grown in temperate zones have more visible rings. The inner portion of the growth ring is formed early, during the growing season. This results in the formation of earlywood or springwood. The outer portion of the rings forms the latewood of the summer wood. It is denser than the inner wood.

Thus, from the above discussion, we can conclude that option C is the right answer.

Note: The annual rings not only tell about the age of the tree but they also reflect the climatic conditions in which the tree grew. Wide rings denote adequate moisture and a long growing season. A narrow ring depicts a drought year in the tree’s life. Direct reading of annual rings is a complex science.