Module 1: Forest Mensuration

The key points from this module are:
The taper of a form refers to the rate of narrowing in diameter in relation to the increase in height of a given 'shape' or 'form'.
The theories of tree form are:

Nutritional theory
Hormonal theory
Metzger's beam theory

Factors affecting the stem profile of individual trees include:

Social position within the stand
Site of the tree
Silvicultural treatments
Genetic parameters

Rules for Measuring the Diameter of a Tree

For standing vertical trees on level ground, measure the diameter at 1.3m vertically.
For a tree on a slope, measure the diameter on the uphill side of the tree.
For a tree with an irregular stem, measure the diameters above and below the obstruction and take the average of the two measurements.
For a tree that is slanted, measure the diameter at a right angle to the tree axis.
For a tree that has a buttress, measure the diameter above the buttress.
For a tree that has a fork below the breast height, consider the tree as two trees and measure two diameters. This does not apply if the fork is above the breast height.

The major tools used in measuring tree diameter are:

Calliper
Tape

Measurement of the height of a tree can be done directly by placing an instrument (poles or strings) along the trunk of a tree and then taking a measurement. A tree's height can also be measured indirectly with the use of two principles: Similar triangles and Trigonometry.