Accuracy of double bark thickness estimation methods used in spruce timber production in Czechia

Bc. Dipl.-Ök. Prince Opoku Peseu

Master's thesis

Abstract:

Abstract Foresters measure diameter over bark (DOB) to determine bark thickness, which they then use to calculate log volume. Poor bucking optimization and out-of-spec logs can diminish returns due to spruce bark thickness estimation errors. Depending on the region, the stand, and the tree, the thickness of the bark varies. Depending on the application, different complexity prediction equations were utilized, such as Polynomial functions and the LinBark function for bark thickness. Growth rate variation appears to be influenced by the site and stands characteristics, which have a significant impact on the thickness of the bark; relative bark thickness decreases with increased site quality. Bark thickness equations customized to local or regional species are used in forestry and forest research to determine the external diameters of bark and diameter measurements of the over bark. To assess a volume of quality timber, foresters must precisely evaluate bark thickness. The objective of this research was to evaluate methods commonly used to estimate double bark thickness in Czechia, as well as to provide a scientific framework for measuring double bark thickness and analysing current estimation methods. I measured 120 spruce logs at the University Forest Enterprise in Kostelec nad Černými lesy. I measured the nominal length (cm), both the small end and large end, diameter over bark (mm), and midspan diameter for each log with a calliper. To evaluate the differences, I used descriptive analysis and multivariate analysis to integrate the real DBT with the two estimates approaches (Polynomial function and LinBark).

Keywords

Diameter over bark, Polynomial functions, LinBark functions

Language used: English

Date on which the thesis was submitted / produced: 10. 4. 2022

Thesis defence

• Supervisor: doc. Ing. Martin Jankovský, PhD.

Czech University of Life Sciences Prague

Faculty of Forestry and Wood Sciences

Master programme:
Tropical Forestry and Agroforestry