Mechanised Harvesting of Broadleaved Tree Species in Europe

Abstract

Purpose of the Review The application of cut-to-length (CTL) technology for harvesting and processing timber from broadleaved tree species is a challenging process, due to thick branches, stem sweep, forks and high wood density. The objective of this review was to describe the current state of harvester use and characterise the effectiveness of mechanised forest operations for broadleaved and mixed forest stands in Europe, paying particular attention to productivity and product quality aspects. An additional aim was to identify the greatest difficulties associated with harvesting broadleaved tree species today and to indicate future challenges and areas for improvement. Recent Findings An interest in wider harvester use for broadleaved tree species started after the storm Lothar in France in 1999. Early experiences demonstrated that lower productivity is common when harvesting broadleaved tree species, due to limitations in delimbing and the high frequency of sweep. Initially, modifications were made to harvester heads, while a newly designed head (CTL 40 HW) was later developed within a European project in 2005–2007. Using various heads, very high productivity was achieved in some cases, but log recovery was unsatisfactory, with large tree tops left without delimbing. The delimbing was of lower quality and log length inaccuracy was observed, as well as economic losses due to damage to plywood caused by feed rollers. These issues resulted in a change in harvester head construction, including work on a patent for a head designed specifically for harvesting broadleaved tree species. Summary The harvester heads that have been developed to date for broadleaved tree species have mainly been used within Central Europe, where the high incidence of broadleaved tree species and their particular morphological features (thick branches and sweep) are a major challenge for CTL technology. There have been many research projects related to this issue: in the last 15 years, there were a few larger initiatives leading to the design and development of harvester heads for broadleaved tree species, with participation from institutions and universities in France, Germany and Poland. There are currently no ongoing initiatives, but the formation of new ones is strongly recommended because today’s forests have a growing share of broadleaved tree species and are being managed to an increasing extent with CTL technology.

Recent Applications of Smart Technologies for Monitoring the Sustainability of Forest Operations

“…As previously mentioned, being a logger is still a dangerous and physically stressful job, and in many countries the attractiveness of this job is decreasing, thus raising the issues of who will be the loggers in the future [108]. Extending the applicability of mechanised harvesting, which is able to also guarantee safer and more comfortable working conditions in steeper terrain and in a wide variety of stands, is a sure determinant to attract young people to a logging career [109]. However, modern technology can also play a significant role, for instance in the application of augmented reality in logger training.…”

Criteria for Assessing the Sustainability of Logging Operations—A Systematic Review

“…The harvester is mainly used in cut-to-length (CTL) operations [55]. Compared to the chainsaw, the harvester has higher productivity [56,57], fewer work injuries and ergonomic problems, and improved occupational safety [58]. However, harvester operation has shortcomings in terms of environmental impact (emissions and soil compaction) [59].…”

“…Especially in steep and rough terrain, there is little alternative to this method of felling [55]. Compared to fully mechanized harvesting operations, the chainsaw has a lower productivity [56,57] and causes a higher rate of tree damage, but on the other hand produces less emissions and higher full-time equivalents 2 [59]. In combination with helicopter extraction, there is hardly any soil compaction.…”

Optimizing Forest Harvesting Efficiency: A Comparative Analysis of Small-Sized Logging Crews Using Cable-Grapple Skidders

“…Lower productivity was attributed to the numerous and thick branches, combined with the frequent presence of trees with multiple treetops. Future technological developments may increase the efficiency of mechanized harvesting of hardwood species and provide a more feasible alternative to the conventional motor-manual wood harvesting [40].…”