Form Quotient is defined as the ratio between the mid-diameter and the dbh.This is postulated by Austrian forester A. Schiffel. It is expressed as;

FQ = mid-diameter/dbh

Types of Form Quotient

1. Normal Form Quotient (Schiffel’sFQ)
2. Absolute Form Quotient (Tor Jonson’s FQ)

Normal Form Quotient

• Schiffel’s FQ developed and defined it as ratio between mid-diameter to dbh. But if tree is just double to the breast (2×1.37m), then FQ will be 1, i.e. defect. To remove the defect, Tor Jonson postulated another formula called absolute FQ.
• Now of historical interest only.

Absolute Form Quotient

• Tor Jonson postulated it as the ratio of diameter or girth of a stem at one half its height above the breast-height to the diameter or girth at breast-height.