Ackerman Pierre A., PhD.

Mechanised Pine Thinning Harvesting Simulation: Productivity and Cost Improvements as a Result of Changes in Planting Geometry

volume: 37, issue: 1

Carbon Footprint of Forest Operations under Different Management Regimes

volume: 37, issue: 1

Comparison of Cable Skidding Productivity and Cost: Pre-Choking Mainline Versus Tagline Systems

volume: 37, issue: .2

The Impact of Log Moisture Content on Chip Size Distribution When Processing Eucalyptus Pulpwood

volume: 37, issue: .2

Diesel Consumption and Carbon Balance in South African Pine Clear-Felling CTL Operations: a Preliminary Case Study

volume: 38, issue: 1

South African Pine Cut-to-Length Harvesting: an Analysis of Fibre Loss and Productivity

volume: 40, issue: 1

A study was conducted in Pinus elliottii and Pinus patula clear-felling stands in the Southern
Cape and Mpumulanga forestry regions of South Africa. A hybrid harvester was observed
over four compartments in a cut-to-length system in order to assess its productivity as well as
its precision with regards to potential fibre loss while processing Pinus elliottii and Pinus patula
for sawlog production. Potential fibre loss results show that the harvester contributes minimally
through inaccurate cross-cutting, accounting for 1.5% of the total wood volume processed.
Converted to a cost, this indicated losses up to € 0.18 m–3 for P. elliottii and € 1.61 m–3
for P. patula. Additionally, the machines were found to be more productive when working with
P. elliottii (32.12 m3 SMH–1) than P. patula (17.55 m3 SMH–1). Based on these findings, the
loss was estimated at up to € 22 650 and € 101 530 y–1 for P. elliottii and P. Patula, respectively.
Species showed to have a significant impact on the processing accuracy, with cross-cutting of
P. patula stems being less precise than P. elliottii. This was attributed to the species’ tendency
to grow thicker branches, although differences in harvesting conditions could have contributed.
Results suggest that harvesting P. patula stands in a CTL system requires more caution since
these can be associated with higher economic losses, and lower productivities. Considering the
recent growth of mechanised CTL harvesting, this study hopefully aids in exploring the efficacy
of a system, which has gone largely untested to date in South African conditions.

Multi-Product Forwarder-Based Timber Extraction: Time Consumption and Productivity Analysis of Two Forwarder Models Over Multiple Products and Extraction Distances

volume: 41, issue:

Accurate predictions in forest operations can be used towards effective planning, costing, and maximizing the productivity of machines in mechanised cut-to-length (CTL) harvesting. There is a general and substantial gap in forwarder productivity data available for pine sawtimber in South Africa at present, and as the number of product assortments being harvested increase there is a need for more work to quantify the effects of extracting products of different dimensions. The aim of this study was to calculate the time consumption and productivity of two models of Ponsse forwarders (15 t and 20 t capacity) to consider and compare the effects of multiple variables including machine capabilities, product assortment, load size, extraction distance and fuel consumption. Productivity averaged at 34.08 m3 per productive machine hour excluding delays longer than one minute (PMH1) for the smaller machine, and 55.94 m3/PMH1 for the larger machine. Productivity and average log volume were strongly positively correlated. Regression models were created for each machine where load volume and extraction distance were both significant factors for predicting productivity. Average fuel consumption of the smaller machine was 15.55 l/PMH1 and 0.47 l/m3, and 20.57 l/PMH1 and 0.43 l/m3 for the larger machine. The product with the largest volume was found to require the least fuel per m3. The models developed could aid in predicting system productivity and potentially carbon emissions under similar conditions in a South African context of industrial plantation forestry.


Web of Science Impact factor (2019): 2.500
Five-years impact factor: 2.077

Quartile: Q1 - Forestry

Subject area

Agricultural and Biological Sciences