A comparison between excavator-based harvester productivity in coppiced and planted<i>Eucalyptus grandis</i>compartments in KwaZulu-Natal, South Africa

Ramantswana, Muedanyi; McEwan, Andrew; Steenkamp, J.

doi:10.2989/20702620.2013.858213

Cited by 16 publications

(13 citation statements)

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“…Although these models represent different curve shapes-linear instead of logarithmic-the graphs are quite near to each other and represent very similar trends. What is more, the estimates obtained from this study are also in agreement with the figures reported in many other studies concerned with the productivity of CTL harvesters in eucalypt plantations, which span a period of 20 years [10,12,[22][23][24][25][26][27][28]. Of course, agreement is not universal, and four short-term time studies conducted in Brazil report productivity figures that are approximately 50% higher than those indicated here [29][30][31][32].…”

Section: Discussionsupporting

confidence: 91%

“…It is also worth noticing that agreement is obtained between productivity studies with very different characteristics: A long-term observational study as presented here; a collection of over 40 short-term studies, lasting one or few hours each [20]; a compilation of five different time studies with widely variable sampling intensity [21]; and nine individual studies, lasting few days each [10,12,[22][23][24][25][26][27][28]. Apparently, different techniques are capable of returning similar figures, all representing viable alternatives to reach the same goal: one may then select one, rather than the others, based on convenience and opportunity.…”

Section: Discussionmentioning

confidence: 99%

“…Harvester use is now commonplace in close-to-nature forestry [7], mixed hardwood stands [8], and Mediterranean coppice forests [9]. Harvesters and processors are also very popular in plantation forestry worldwide, especially in the Iberian region [10], Italy [11], South Africa [12], and South America [13], where they perform most of the harvesting in the industrial pine, poplar, and eucalypt plantations. The overwhelming popularity of harvesters across widely variable regions is helped by their remarkable adaptability, which allows converting general purpose prime movers into efficient forest machines by installing a detached harvester head [14].…”

Section: Introductionmentioning

confidence: 99%

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Decreasing the Fuel Consumption and CO2 Emissions of Excavator-Based Harvesters with a Machine Control System

Spinelli

Moura

2019

Forests

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Compared with purpose-built units, excavator-based harvesters offer many advantages, but they also face one main limitation: a much higher fuel consumption, which also results in higher CO2 emission levels. The fuel efficiency of excavator-based harvesters can be increased by a better interface between the excavator and the harvester head. This study aimed to determine the performance of a new adaptation kit, specifically designed to improve the communication between these two components. The new kit offers real-time adjustment between the power demand of the harvester head and the power output of the excavator, which should help reducing fuel consumption while stabilizing hydraulic fluid temperature. The test was conducted on 53 excavator-based harvesters purchased and managed by a large Brazilian company. Time use, fuel consumption and production were monitored continuously for one full month, before and after installation of the kit. Overall, the study covered 40,000 h of work, during which the harvesters cut, processed, and debarked 4.5 million trees, or 650,000 m3 of wood, under bark. Fuel consumption amounted to 900,000 liters. After installing the adaptation kit, productivity increased 6%, while fuel consumption per hour decreased 3.5%. Fuel consumption and CO2 emissions per product unit decreased 10%, as an average. The effect of random variability typical of an observational study prevented formulating an accurate figure for the amount of fuel that can be saved by installing the adaptation kit. Yet, one may confidently state that, in most cases, installing the kit results in a reduction of fuel use, and that such reduction is most often in the range from −10 to −20% on a per m3 basis.

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Section: Discussionsupporting

confidence: 91%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Decreasing the Fuel Consumption and CO2 Emissions of Excavator-Based Harvesters with a Machine Control System

Spinelli

Moura

2019

Forests

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“…In recent decades, mechanised forest harvesting systems have been widely adopted, primarily to reduce harvest costs and improve worker safety. Time-and-motion studies of mechanical harvesting operations have been undertaken to better understand the effect of harvesting systems (Visser and Spinelli 2012), machine type and configuration (Ghaffariyan et al 2012), machine-operator training, behaviour and experience (Ovaskainen et al 2004), terrain (Visser and Spinelli 2012;Visser et al 2009), and stand and tree characteristics Ramantswana et al 2012;Ramantswana et al 2013;Spinelli et al 2002) on harvest productivity. In the short term, knowledge gained from such studies can be used to optimise machines, operator behaviour and harvesting systems but, in the longer term, may be used guide decisions relating to the procurement and sale of land, silvicultural practices, rotation length and tree breeding (Schäfer and Ponce 2007;Whittock et al 2004) Many stand and individual-tree characteristics that potentially affect harvest productivity are known to be under genetic control in commercially-grown tree species (Hamilton and Potts 2008;Potts et al 2004).…”

Section: Introductionmentioning

confidence: 99%

Genetic control of Eucalyptus globulus harvest traits

et al. 2015

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The cost of harvesting short-rotation plantation eucalypts can be in excess of AU$2500·ha−1. Despite this high cost, the extent to which harvesting productivity is affected by tree genetics is not well understood. We address this issue in a study of two 10-year-old genetic field trials of Eucalyptus globulus Labill. in Australia. Standing-tree traits analysed were survival, diameter at breast height, basal area, and stem straightness and forking. Harvest traits analysed were volume, time, and productivity. Genetic group and within-group genetic variation (additive and dominance), stand-level family variation, phenotypic and genetic correlations, and the effects of inbreeding were estimated for these traits. The different scenarios studied showed that plantation harvest productivity was affected by tree genetics to some degree but was mainly affected through positive covariation with stem diameter. Harvest productivity is thus unlikely to have been adversely affected by past selection. Although no significant additive or dominance genetic variation in stem forking or straightness was detected, weak phenotypic correlations were consistent with harvest productivity being higher in straighter trees with no forking. High inbreeding depression was evident for growth and survival; however, in open-pollinated progeny, this resulted in only a slight reduction in harvest productivity (5.5%) compared with out-crossed progeny.

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“…Several studies have focused on the effect of stump crowding on harvester productivity and cost (Ramantswana et al 2013;Spinelli et al 2016), but none has address its effect on value recovery. Stump crowding represents a physical obstacle to harvester work, preventing the harvester to firmly grab the stem to be cut.…”

Section: Introductionmentioning

confidence: 99%

The effect of coppice management on stump volume recovery in mechanized operations

Ramantswana¹,

McEwan²,

Spinelli³

2017

Annals of Forest Science

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& Key message Coppice stands result in slightly higher stump waste compared with planted stands, when felled mechanically by a harvester. & Context The large demand for wood fibre requires efficient production and cost-effective practices throughout the supply chain. & Aims The purpose of the study was to quantify the amount of volume lost to excessive stump height in coppiced and planted stands. & Methods Stump height was measured on similar eucalypt stands that differed only for their origin: coppiced or planted. The study sample comprised of 543 planted stems and 851 coppice stems; of which 365 grew as double stems and 486 as single. & Results Stump waste was highest for coppiced double stumps, smallest for coppiced single stumps and intermediate for planted tree stumps. All differences were statistically significant, but the difference between coppiced single stumps and planted tree stumps was much smaller (20%) than the difference between coppiced double stumps and the rest (220-260%). Regression analysis showed that stump waste volume increased with tree volume, and this effect was twice as large for coppiced double stumps compared with the other treatments. Stump waste seemed very small in both relative and absolute terms and is unlikely to offset the large benefits accrued through coppice management and mechanization. & Conclusion Comparison with previous stump height studies indicates that the results obtained in this experiment for planted eucalypt may have general value and could be extended to other coppice stands, although with caution.

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A comparison between excavator-based harvester productivity in coppiced and plantedEucalyptus grandiscompartments in KwaZulu-Natal, South Africa

Cited by 16 publications

References 4 publications

Decreasing the Fuel Consumption and CO2 Emissions of Excavator-Based Harvesters with a Machine Control System

Decreasing the Fuel Consumption and CO2 Emissions of Excavator-Based Harvesters with a Machine Control System

Genetic control of Eucalyptus globulus harvest traits

The effect of coppice management on stump volume recovery in mechanized operations

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