FOREST
PRODUCTIVITY
COUNCIL
of British Columbia

Forest Productivity Council Policy

TOP HEIGHT DEFINITION

June 30, 1998

Top height is the height of the largest diameter tree on a 0.01 ha plot, providing the tree is suitable.

Suitable trees are trees which provide heights and ages that can be validly used to estimate site index. This means that the top height tree must be healthy, not have a broken or damaged top, and not have its height growth affected by a competitor. The tree should not be a residual left from previous logging. If the largest diameter tree does not meet these criteria then no top height sample is taken (a "null" plot). The largest diameter tree is selected regardless of species.

For the purposes of measuring top height to establish green-up criteria, as defined in Section 68 of the Operational Planning Regulation, the measurement criteria for top height shall be the tallest tree on a 0.01 ha plot.

In some cases, such as mixed species stands, where the top height tree is not suitable in the 0.01 ha plot, an alternative tree may be selected but this height will be termed "site height".

An account of the Technical Advisory Committee’s deliberation, including specific technical references, is detailed in the report "Definition and Estimation of Top Height for Site Index".

Last updated: 01/13/99