The effect of tree and harvester size on productivity and harvester investment decisions

Ackerman, Simon; Talbot, Bruce; Astrup, Rasmus

doi:10.1080/14942119.2021.1981046

Cited by 8 publications

(15 citation statements)

References 31 publications

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“…The productivities were higher than those presented in other studies on long term data (Wenhold et al 2020) and in observational time studies presented by Williams & Ackerman (2016). Similarly, these figures are also higher than the modelled productivities in Ackerman et al (2022).…”

Section: Productivity In Relation To Machine Derived Tree-size Distri...mentioning

confidence: 63%

“…It is normal practice for the company to have the two larger or the two smaller harvesters working in pairs in the same stand. The mean tree number for all the sites was 4026 (minimum of 164 tree and maximum of 13016), this variation is due to partial completion of stands (not the full area being harvested before these data were downloaded and processed) and to a lesser extent to basic data cleaning as per the method detailed in Ackerman et al (2022). The DBH distribution of the data did remain somewhat consistent between the 10 th and the 90 th percentile.…”

Section: Stand Tree Size Distributionsmentioning

confidence: 93%

“…Traditional tree size related productivity curves are common, also the notion that these curves reach a point where the productivity levels out, mainly based on the size of the machine. The rate of change in productivity, or marginal productivity has been found to be greater in smaller trees than in larger trees (Eriksson & Lindroos 2014) while in Ackerman et al (2022) the intermediate area showed the greatest rate of change. However, when the tree size becomes too large for the machine to handle the productivity of the machine drops off, as quantified by (Visser et al 2009;Alam et al 2014;Ackerman et al 2022).…”

Section: Productivity Of Machines In Target Tree Dimensionsmentioning

confidence: 98%

“…The rate of change in productivity, or marginal productivity has been found to be greater in smaller trees than in larger trees (Eriksson & Lindroos 2014) while in Ackerman et al (2022) the intermediate area showed the greatest rate of change. However, when the tree size becomes too large for the machine to handle the productivity of the machine drops off, as quantified by (Visser et al 2009;Alam et al 2014;Ackerman et al 2022). Productivity functions whether linear or non-linear always reflect a rate of productivity for a given interval of tree size.…”

Section: Productivity Of Machines In Target Tree Dimensionsmentioning

confidence: 98%

“…When the investment decision is made to purchase cut-to-length (CTL) harvesters, which require a high capital outlay, the enterprise needs to ensure that they will be applied to the optimal timber size classes to be most effective (Ackerman et al 2022). Studies have also shown that beyond a certain tree size the variability in productivity between machines tends to increase Ackerman et al 2022) and a certain machine size class has a 'sweet spot' or optimum productivity range with regards to the tree size it is applied to (Visser et al 2009;Ackerman et al 2022). This is where the machine can be expected to operate optimally based on its technical specifications.…”

Section: Productivity Of Machines In Target Tree Dimensionsmentioning

confidence: 99%

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Understanding the Influence of Tree Size Distribution on the CTL Harvesting Productivity of Two Different Size Harvesting Machines

Ackerman

Bekker

Astrup

et al. 2022

Preprint

Self Cite

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Tree size determines harvester productivity. Stand management determines tree size distributions. Understanding the effect of tree size distribution on harvesting productivity is central for optimizing management of operations. To investigate tree size distribution on harvester productivity, productivity functions for a medium and larger-sized harvesters were applied to harvester derived tree size distributions from 35 clearfelled pine stands. These functions were applied to a normal distribution of trees covering the same tree size ranges. Productivity differences were analysed on a stand-by-stand basis. Results showed that for the large harvester, productivity rates remained constant (67.1 vs 67.6 m3 PMH− 1) indicating relatively little sensitivity to variations in tree size distributions. Although the standard deviation (SD) halved from 11.6 to 5.6 in the case of the uniform tree distribution. The smaller harvesters, productivity decreased by 15% from 47.3 to 40.1 m3 PMH− 1 and the coefficient of variation (CV) by 6% in the same transition to a uniform distribution. Further investigation was done on more skewed tree size distributions, a family of nine Weibull distributions was generated, representing combinations of three mean DBH classes (25cm, 30 cm, and 35cm) and three levels of CV (15%, 20%, 25%), for each DBH class. Results clearly indicate that different distribution shapes have different effects on different machine sizes, and that a low CV correlates to a higher productivity in larger tree sizes. A more uniform tree size distribution also provides more predictable results (lower CV), which would promote machine scheduling and result in fewer discrepancies on production rates.

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Section: Productivity In Relation To Machine Derived Tree-size Distri...mentioning

confidence: 63%

Section: Stand Tree Size Distributionsmentioning

confidence: 93%

Section: Productivity Of Machines In Target Tree Dimensionsmentioning

confidence: 98%

Section: Productivity Of Machines In Target Tree Dimensionsmentioning

confidence: 98%

Section: Productivity Of Machines In Target Tree Dimensionsmentioning

confidence: 99%

See 3 more Smart Citations

Understanding the Influence of Tree Size Distribution on the CTL Harvesting Productivity of Two Different Size Harvesting Machines

Ackerman

Bekker

Astrup

et al. 2022

Preprint

Self Cite

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Understanding the influence of tree size distribution on the CTL harvesting productivity of two different size harvesting machines

Ackerman,

Bekker,

Astrup

et al. 2024

Eur J Forest Res

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Tree size is one of the major factors that determines harvester productivity and is heavily influenced by forest managerial activities. Stand silvicultural management can lead to managing tree size, the distribution of tree size, and tree height amongst others. Understanding the effect of tree size distribution on harvesting productivity is central for optimizing management of operations. To investigate the effects of tree size distribution on harvester productivity, productivity functions for a medium and larger-sized harvester were applied to harvester derived tree size distributions from 35 clearfelled pine stands. These functions were applied to a normal distribution of trees covering the same tree size ranges. Productivity differences were analysed on a stand-by-stand basis. Results showed that for the larger harvester, productivity rates remained constant (67.1 vs. 67.6 m3·PMH− 1) indicating relatively little sensitivity to variations in tree size distributions. Although the standard deviation (SD) halved from 11.6 to 5.6 in the case of the uniform tree distribution. The smaller harvester productivity decreased by 15% from 47.3 to 40.1 m3·PMH− 1 and the coefficient of variation (CV) by 6% in the same transition to a uniform distribution. Further investigation was done on more skewed tree size distributions, a family of nine Weibull distributions was generated, representing combinations of three mean DBH classes (25 cm, 30 cm, and 35 cm) and three levels of CV (15%, 20%, 25%), for each DBH class. Results clearly indicate that different distribution shapes have different effects on different machine sizes, and that a low CV correlates to a higher productivity in larger tree sizes. A more uniform tree size distribution also provides more predictable results (lower CV), which would promote machine scheduling and result in fewer discrepancies on production rates.

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Conception of a predictive maintenance system for forest harvesters from multiple data sources

Fauth,

Ligocki

2024

Procedia CIRP

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The effect of tree and harvester size on productivity and harvester investment decisions

Cited by 8 publications

References 31 publications

Understanding the Influence of Tree Size Distribution on the CTL Harvesting Productivity of Two Different Size Harvesting Machines

Understanding the Influence of Tree Size Distribution on the CTL Harvesting Productivity of Two Different Size Harvesting Machines

Understanding the influence of tree size distribution on the CTL harvesting productivity of two different size harvesting machines

Conception of a predictive maintenance system for forest harvesters from multiple data sources

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