A Robust Productivity Model for Grapple Yarding in Fast-Growing Tree Plantations

Riaan Engelbrecht,Raffaele Spinelli,Andrew Mcewan

doi:10.3390/f8100396

Abstract

New techniques have recently appeared that can extend the advantages of grapple yarding to fast-growing plantations. The most promising technique consists of an excavator-base un-guyed yarder equipped with new radio-controlled grapple carriages, fed by another excavator stationed on the cut-over. This system is very productive, avoids in-stand traffic, and removes operators from positions of high risk. This paper presents the results of a long-term study conducted on 12 different teams equipped with the new technology, operating in the fast-growing black wattle (Acacia mangium Willd) plantations of Sarawak, Malaysia. Data were collected continuously for almost 8 months and represented 555 shifts, or over 55,000 cycles—each recorded individually. Production, utilization, and machine availability were estimated, respectively at: 63 m3 per productive machine hour (excluding all delays), 63% and 93%. Regression analysis of experimental data yielded a strong productivity forecast model that was highly significant, accounted for 50% of the total variability in the dataset and was validated with a non-significant error estimated at less than 1%. The figures reported in this study are especially robust, because they were obtained from a long-term study that covered multiple teams and accumulated an exceptionally large number of observations.

Highlights

Compared with natural forests, tree plantations offer many benefits, including fast growth, rationalized management and pre-defined product target [1]
Bhd consortium consortium 45 km east of thethe large plantation established of Bintulu, in Sarawak, Malaysia
While data imbalance and various errors may have weakened the accuracy of the results, the study is still able to determine the effect of the most important variables that affect productivity, and offers a regression model that is highly significant, accounts for 50% of the total variability in the dataset, and is validated with a non-significant error estimated at less than 1%

Summary

Introduction

Compared with natural forests, tree plantations offer many benefits, including fast growth, rationalized management and pre-defined product target [1]. Industrial tree plantations are characterized by very high yields, which result from the use of selected genotypes under favorable soil and climate conditions [2]. The fastest growing tree plantations are found in the Southern Hemisphere, and yield up to 40 m3 of solid wood per hectare per year [3]. Many forest companies in Europe and North America have transferred their capital away from domestic forest ventures [4] and towards highly-productive plantations in South America, South Africa, and Australasia [5]. Plantation forestry has an enormous potential for the efficient supply of fiber and renewable fuel [6], and may already account for almost half of the global production of industrial wood [7]. Experts estimate that the importance of plantations will continue to grow [8], and that by

Objectives

Methods

Results

Discussion

Conclusion