Question

Age of the tree can be measured by-
a. Its height and girth
b. Biomass
c. Number of annual rings
d. Diameter of its heartwood

Answer 1

Hint: The horizontal cross section passes across a tree's trunk (i.e. vascular tissue patterns). This derives from the shift in growth rate over the various seasons of the year.

Complete answer:
> Option A is incorrect. For both height and girth, the base of the tree is measured as the elevation at which the tree's pith intersects the ground surface below, or "where the acorn sprouted." This is known to be halfway between the ground level at the upper and lower sides of the tree on a slope. With varying degrees of precision, tree height can be calculated in a variety of ways.

> Option B is incorrect. Biomass, usually expressed in weight, is a measure of biological matter. A forest's biomass is a complex subject that involves all plants, trees, fungi, insects, etc. The biomass of a tree can be that of a single person or all individuals occupying an area unit.

> Option C is correct. The tree forms new cells each year, arranged in concentric circles called annual rings or rings of annual growth. The quantity of wood produced during one growing season is shown by these annual rings. A ring marks a full cycle of seasons in the life of the tree, or one year.

> Option D is incorrect. A term "Heartwood" is used to describe the wood that is at the core of a tree. It is also referred to as duramen, dead, central tree wood. The cells normally contain tannins or other substances that make them dark and often aromatic in colour. It is shaped from "retired" old sapwood and becomes the tree's powerful spine. As it is much less vulnerable to fungi and contains far less moisture than sapwood, Heartwood is favoured for woodworking, which ensures that when it dries, it can shrink less.

Hence, the correct answer is option (C).

Note: Tree rings evolve because new water and food conducting cells (tracheids) are inserted across the circumference of the tree trunk during each growth season. With thinner walls, cells in spring growth appear to be larger than the previous collection of cells formed at the end of the following summer.