- Title
- Determining productivity, residual damage and cost of two alternative harvesting systems in pinus elliottii thinning
- Creator
- Dembure, Tigere Pasca
- Creator
- Spinelli, Raffaele
- Creator
- Ramantswana, Muedanyi
- Subject
- Pinus caribaea
- Subject
- Forests and forestry Logging Harvesting -- South Africa
- Date Issued
- 2018
- Date
- 2018
- Type
- Thesis
- Type
- Masters
- Type
- MSc
- Identifier
- http://hdl.handle.net/10948/22016
- Identifier
- vital:29813
- Description
- Pinus elliottii is the second most dominant softwood grown in the South African plantation forestry industry. It possesses desirable timber characteristics and is useful for production of solid wood products. In the silviculture of softwoods (grown for solid wood products), thinning is an important tending operation. It is necessary for stand hygiene and volume increment of residual trees through the creation of growing space. The selection of a suitable harvesting system for thinning is vital. The system of choice has to attain higher productivity, cause the least damage to residual trees and must be cost effective. From as early as 2000 the South African forestry industry witnessed a general shift towards the use of fully mechanised cut-to-length harvesting systems. This has been a result of high labour turnover, increased labour costs, increased timber demand and the effects of HIV and AIDS on forestry workers. With this recent introduction of mechanised systems, they have not been benchmarked against conventional harvesting systems. In this regard, two harvesting systems were studied side-by-side for productivity, residual damage and cost in a seventh row second thinning operation in P. elliottii stands. First thinnings generate poor financial returns since small trees are harvested and they have a relatively low financial value but have a relatively high operational cost per unit harvested. The second thinning operation is usually the thinning operation that is most likely to result in an intermediate financial return for the organisation, hence the need to benchmark these harvesting systems during the second thinning. These systems were a fully mechanised cut-to-length (CTL) and a semi-mechanised tree length (TL) system. The fully mechanised system comprised of a harvester (felling) and a forwarder (extracting) and the semi-system consisted of felling by chainsaw, tractor extraction, roadside processing by chainsaw and stacking by three-wheeled logger. Two uniform compartments planted with P. elliottii were selected for the study. A total number of 32 plots (16 plots per compartment) were marked and randomly assigned between the two treatments, each plot comprised of seven rows, with the middle row clear-cut and three rows on either side, where marked trees were selectively removed. Within each plot, the number of removal trees ranged from 80 to 105. The diameter, height and form of each removal tree were measured to determine tree volume and ultimately determine productivity. Before analysis, plot characteristics were compared to determine if conditions were equal for both treatments using the Mann-Whitney test at alpha level ˂ 0.05. There was a statistically significant difference in total operator efficiency between the two systems (p ˂ 0.0001). The fully mechanised system attained higher levels of productivity than the semi-mechanised system (15.58 m3/SMH versus 5.26 m3/SMH, for felling and 15.56 m3/SMH versus 5.29 m3/SMH, for the extraction operation). Operator productivity comparisons were restricted to the two harvester operators, and one operator achieved 16.9 m3/SMH while the other operator achieved 14.3 m3/SMH. Different operator working technique contributed to the productivity differences with one operator spending (on average) four seconds less per tree on the fell-process work element. Residual tree damage was assessed immediately after all felling and extraction had taken place. Damage size was measured as ellipse surface area. For each record of residual damage, the damage type was noted, damage position along the stem, and tree position from extraction trail. The most predominant damage type was bark peel. The motor-manual system caused five per cent damage and the fully mechanised system inflicted only three per cent damage to the residual trees. Residual tree damage from the semi-mechanised system mainly occurred at the root zone, and occurred more frequently on edge trees. The mechanised CTL system was characterised by high investment and operational costs. The mechanised system incurred 3037.75 R/SMH while the semi-mechanised system incurred 1667.10 R/SMH. The difference in total costs per year between both systems was 56.29 per cent, with the fully mechanised system being more expensive. The high capacity and the superior technology of mechanised harvesting systems may not be fully exploited in thinnings, therefore harvesting systems with lower capital costs and reasonable productivity can be competitive.
- Format
- xv, 134 leaves
- Format
- Publisher
- Nelson Mandela University
- Publisher
- Faculty of Science
- Language
- English
- Rights
- Nelson Mandela University
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