Masters Degrees (Forest and Wood Science)

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Browsing Masters Degrees (Forest and Wood Science) by Subject "Agricultural residues"

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    Evaluation of a mechanized CTL harvesting system in different geometric thinning operations in terms of productivity, cost, biomass conversion, residual stand damage and spacing uniformity
    (Stellenbosch : Stellenbosch University, 2021-12) Makoto, Munyaradzi; Talbot, Bruce; Ackerman, Simon; Stellenbosch University. Faculty of AgriSciences. Dept. of Forest and Wood Science.
    ENGLISH ABSTRACT: This study was aimed at comparing conventional 7th row thinning with diagonal thinning in terms of productivity, cost, biomass conversion efficiency, residual stand damage and spacing uniformity. The study was based on two adjacent Pinus patula compartments on the Mpumalanga Highveld. A time study was conducted to test time consumption and productivity of both harvesting and forwarding between the two treatments. Residual tree damages were assessed by inspecting all individual trees within research plots for any woundings. Cost calculations were carried out on each machine per thinning treatment to determine which machine was more cost-effective. Voronoi polygons and simulations were used to determine spacing uniformity and biomass conversion efficiency was tested by enumerating woody residues that were above the commercial limit diameter remaining in the stand after timber extraction. iii Summary This study was aimed at comparing conventional 7th row thinning with diagonal thinning in terms of productivity, cost, biomass conversion efficiency, residual stand damage and spacing uniformity. The study was based on two adjacent Pinus patula compartments on the Mpumalanga Highveld. A time study was conducted to test time consumption and productivity of both harvesting and forwarding between the two treatments. Residual tree damages were assessed by inspecting all individual trees within research plots for any woundings. Cost calculations were carried out on each machine per thinning treatment to determine which machine was more cost-effective. Voronoi polygons and simulations were used to determine spacing uniformity and biomass conversion efficiency was tested by enumerating woody residues that were above the commercial limit diameter remaining in the stand after timber extraction. Harvesting results showed a significant difference between the two treatments at (p < 0.05). Conventional 7th row thinning had the highest mean productivity at 16.49 m3/PMH compared to 14.36 m3/PMH for diagonal thinning. Forwarding results also showed a significant difference between the two treatments at (p < 0.05). Diagonal thinning had a mean productivity of 4.61 m3/PMH compared to 5.36 m3/PMH for the conventional 7th row thinning. The conventional 7th row thinning method had the lowest cost of R273.93/ m3 compared to R324.28/ m3 for diagonal thinning. Residual tree damages showed a significant difference between the two treatments at (p < 0.05). Diagonal thinning had an average residual tree damage of 8.9% compared to 4.4%. The diagonal thinning method had the highest fibre losses at 12.65 m3/ha and 10.52 m3/ha for conventional 7th row thinning. There was a significant difference between the two treatments. The study showed that conventional 7th row thinning is a better method in terms of productivity, cost and residual tree damages. Diagonal thinning, however, proved to be better in terms of thinning quality with regards to improving spacing uniformity and improving size distributions.