Open access publications in the SLU publication database

Abstract

In this paper, critical length sampling for estimating the volume of downed coarse woody
debris is presented. With critical length sampling, the volume of downed dead wood in a
stand can be determined by summing the critical lengths of trees included in the sample.
The critical length of a downed tree is the length of the &em section, which from a certain
sample point is coarse enough to be counted when a relascope is used. In comparison to
traditional relascope sampling, where the instrument is held vertically during the mea­
surements, the instrument is operated horizontally.
By combining critical length sampling with critical height sampling-a method
previously described for estimating the volume of standing trees -the total volume of
dead wood can be estimated in a stand. It is proposed that the main area of use of the
combined method would be in connection with rapid in-place inventories where a quick
estimate of the volume of dead wood is needed. In this context, the combined critical
height-critical length method provides a relatively simple means for obtaining such an
estimate.
In this report, the theoretical background is described and a short description of the use of
the method in the field is presented. The report should be considered as a simple first
description of the method, which will later on be complemented with a more compre­
hensive proof, efficiency comparisons with other methods, and experiences from field
tests.