Double Bark Thickness Estimation Models of Common European Broadleaved Species for Harvester Timber Volume Estimation in Czechia

Abstract

The share of the annual volume of harvester-produced timber in Czech forest bioeconomy has increased in the last decades. To estimate under-bark timber volume, harvester systems allow choosing between two different bark deduction models – diameter band (DBM) and linear model. However, linear models were not calibrated for the conditions of Czech forestry. Therefore, the objective of this research was to develop, for local conditions in Czechia, linear functions for estimating the double bark thickness of two groups of broadleaved species (beech and oak) and to test their viability based on real harvest data. To create the linear functions, official Czech cubing tables were used. Data from real harvests were gathered from fifteen harvesters. A sample containing 4995 logs belonging to the beech group was analyzed using descriptive statistics and the Paired Wilcoxon tests. The mean double bark thickness for beech group was 15.1 mm (polynomial and linear model). For oak group, it was 15.48 mm (polynomial) or 15.49 mm (linear). The results of real harvests for beech group revealed that the mean double bark thickness estimated by the polynomial function was 7.08 mm. The linear function estimates were closer to the value estimated by the polynomial (6.84 mm) than DBM estimates (6.68 mm). Therefore, we can state that the newly developed linear models can be used in fully mechanized harvesting instead of manual bark deduction methods in Czechia.

Evaluation of stress loading for logging truck drivers by monitoring changes in muscle tension during a work shift

“…Our study expands on the studies that use measurements of bioindicators to observe the workload of forest harvester operators (Macků and Dvořák 2011;Jankovský et al 2013Jankovský et al , 2018Škvor 2018) and forwarder operators (Škvor 2020) to making observations of logging truck drivers. Similar studies have been carried out for long-distance transportation of goods (long and timeconsuming journeys, mostly on motorways) (Hege et al 2019) and for the transport of goods by smaller vans (short routes, mostly in urban areas) (Romeo et al 2018).…”