Mechanised Harvesting of Broadleaved Tree Species in Europe

Piotr S Mederski,Mariusz Bembenek,Andreja Đuka,Janine Schweier,Petros Tsioras,Leo G Bont

doi:10.1007/s40725-021-00154-7

Abstract

Purpose of the ReviewThe 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 FindingsAn 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.SummaryThe 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.

Highlights

In contrast to harvester use for forest operations in conifer stands, the use of harvesters in broadleaved forest stands has a relatively short history
Broadleaved tree species occur in all regions, with South-West Europe having the largest share of forest stands with deciduous tree species (Table 1)
In North Europe, difficulties with harvester use for broadleaved species were observed in the multi-tree harvesting of trees with sweep; other difficulties were in accuracy of log length, while in Central (West and East) and South-East Europe, harvester use for broadleaved species has more potential limitations

Summary

Introduction

In contrast to harvester use for forest operations in conifer stands, the use of harvesters in broadleaved forest stands has a relatively short history. This is because harvesting and processing timber from broadleaved species is more difficult than from coniferous tree species e.g. spruce and pine. The use of harvesters for broadleaved species was rather sporadic at the end of the twentieth century. This changed after wind damage resulting from the storm Lothar in 1999, when large areas needed clearing and harvesters were a suitable option in comparison to low-safety motor-manual salvage removal [6]. The need for wider harvester use led to head modifications to make timber processing more effective and with satisfactory productivity [2]

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