Epsilon Archive for Student Projects

Abstract

Tree marking activities are usually assumed to follow textbooks and management plan
guidelines. However, initial experiments starting in the 1990s have shown that there is
much room for personal interpretation by field and operational staff. This study presents
an analysis of tree selection variability among people selecting trees in marteloscopes as
part of silvicultural training activities. The analysis has been done for two different
thinning types, i.e. low and crown thinning, as well as for the selection of frame trees in
twelve different forests in the United Kingdom.
Two different methods have been used for assessing the agreement among participants,
i.e. Fleiss’ kappa and a method based on the test statistic of the χ2 goodness-of-fit test.
The Pearson correlation coefficient was calculated to identify possible relationships
between the aforementioned two agreement characteristics and the structural parameters
of the forests. In general the agreement between test persons was low for all types of tree
selection. Overall, the agreement was higher for low thinning exercises followed by the
selection of frame trees and the marked frame-tree competitors in crown thinnings. Both
agreement characteristics indicated that test persons tend to agree more when selecting
trees for low thinnings and when selecting frame trees. There were no consistent patterns
that suggest that the structure of the forest influences the level of agreement between test
persons.