A Long-Term Follow-Up Study of Slash Bundling in Fast-Growing Eucalypt Plantations

Matevž Mihelič,Alberto Assirelli,Raffaele Spinelli,Natascia Magagnotti,João Pedro Martins

doi:10.3390/f12111548

Abstract

The Authors conducted a long-term follow-up study of a John Deere 1490 forwarder-mounted bundler owned by a Portuguese company and used for bundling logging residues from fast-growing eucalypt plantations located in Portugal and Spain. The study spanned 7 years, from 2011 to 2016. During this time, the machine clocked over 11,500 h and produced more than 200,000 bundles or 75,000 green tons of biomass. Bundle length was commonly 2.4 m, and bundle mass averaged 350 kg. Overall, the database contained 1752 daily records. Bundling productivity averaged 19 bundles per productive machine hour (meter hour, excluding all major delays). Mechanical availability was very high and averaged 93%. Utilization commonly ranged between 65% and 75%. Use and productivity showed a predictable seasonal trend and a slight decline over time. The latter might be due to wear, but also due to the increasingly challenging conditions faced by the company as the average worksite size sharply decreased from 2011 onwards. While almost extinct elsewhere, bundling seems to thrive in the Iberian plantations, possibly due to the industrial character of both eucalypt farming and bioenergy generation in the region. That allows the reaping of all integration benefits offered by bundling, while the cost of setting up a parallel biomass chain is minimized. Furthermore, bundling seems the ideal technique for efficient residue recovery where slash yields are low and roadside storage space is limited: these are the typical constraints of industrial eucalypt plantations, where planted area is maximized (=little landing space) and the largest possible proportion of the tree mass is turned into pulpwood (=relatively low residue yield).

Highlights

In its natural state, logging residue is not dense enough for efficient handling: it requires compaction, which is normally achieved by either comminution or packing
While the financial interest associated with meticulous accounting makes it unlikely that delivery records were less than accurate, ticket weights were not associated with moisture content records and interpretation of these data was complicated by the variability introduced by the inevitable fluctuation in moisture content, due to seasonal variations and to the variable delays between bundling and delivery
Sanchez-Garcia et al [13] do report very large moisture content variations for bundled eucalypt slash in Spain, and that warns us about cautious interpretation of the mass figures in this study—not because they are likely incorrect, but rather because they may reflect the inevitably large variability in moisture content that characterizes eucalypt slash

Summary

Introduction

In its natural state, logging residue is not dense enough for efficient handling: it requires compaction, which is normally achieved by either comminution or packing. By 2003 over 700,000 bundles were being produced annually in Finland [5], and by 2005 Finnish logging companies had already deployed 30 bundlers, mounted on medium size forwarders, in order to manufacture their bundles directly on the cutover and accrue the benefits of compaction as early as possible along the supply chain [6]. This aroused the interest of European, American, and Australian stakeholders, who commissioned a number of trials and pilot projects [7,8,9,10,11,12]. All this anticipation did not develop into the global success expected by many, and ten years later slash bundling had faded away as a large business opportunity with some notable exceptions

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