Question

What is an annual ring?

Answer 1

Growth ring, the increase of wood added during a single growth cycle in a cross section of the stem of a woody plant. Growth rings are separate if the cells formed early in the growth cycle are larger (spring or early, wood) than those created later (summer or late, wood) or if growth ends.

Complete answer:
The growth cycle in temperate regions is normally one year in which case the growth ring may be considered a "annual ring." Growth rings may not be discernible or are not annual in tropical regions. Development rings are often absent even in temperate areas, and a second or "false" ring may be deposited within a single year, such as after insect defoliation.

The alternation of spring wood and autumn wood in a concentric circle on the trunk is the annual ring.

If a plant is young, the stem is young as well. The vascular cambium is present as a single layer at this point. As the stem grows, the complete ring is shaped, called the cambial ring. The Cambial Ring contributes to secondary xylem and secondary phloem formation. Medullary rays are also caused by the cambial ring.

The behaviour of Cambial is affected by environmental variables. Cambium is active during the spring and gives rise to wood with a lot of xylary elements with wider cavities in vessels. This form of wood is known as early wood or spring wood.
Cambium is inactive during winter and gives rise to wood with a smaller number of xylary elements with narrow cavities. This timber is known as autumn timber or late wood.

These two forms of wood appear on the trunk in two concentric circles and form an annual n-ring together. In one year one annual ring is created. In determining the age of the trees, annual rings are beneficial.

Note: A tree's growth rate can be compared to a child's development. A young sapling is much quicker to grow than an adult tree. At the beginning of its existence (in the centre), a cross section of an older tree reveals rings that are very large but which gradually become smaller. An old tree develops very small rings and its development in diameter and height is much slower.