Browsing by Author "Talbot, B."

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    A comparison of two methods of data collection for modelling productivity of harvesters : manual time study and follow-up study using on-board-computer stem records
    (Marin Dracea National Research-Development Institute in Forestry, 2018) Brewer, J.; Talbot, B.; Belbo, H.; Ackerman, P.; Ackerman, S.
    Abstract. Productivity of a mechanized P. patula cut-to-length harvesting operation was estimated and modelled using two methods of data collection: manual time study and follow-up study using StanForD stem files. The objective of the study was to compare the productivity models derived using these two methods to test for equivalence. Manual time studies were completed on four different machines and their operators. Two Ponsse Bear harvesters fitted with H8 heads, and two Ponsse Beaver harvesters, fitted with H6 heads, were included. All machines were equipped with Ponsse Opti2 information system. All four operators had approximately 1 year of experience working with their respective machines. The four machines worked in separate four-tree-wide harvesting corridors, and they each harvested 200 trees. Individual tree diameter at breast height (DBH), and height measurements were made manually. Subsequently, data on the trees in each study were extracted from the StanForD stem reports from each of the harvesters. Cycle times in the stem reports were determined based on the difference between consecutive harvest timestamps. The two methods were compared in terms of their abilities to estimate equivalent measures for tree DBH, volume, and productivity. In all four cases, significant differences were found between the DBH and volume measures derived using the two methods. Subsequently, the volume measures from the manual methods were used as the basis for productivity calculations. Results of the productivity comparisons found no significant differences between the models developed from the two methods. These results suggest that equivalent productivity models can be developed in terms of time using either method, however volume discrepancies indicate a need to reconcile bark and volume functions with the high variability experienced in the country.
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    Reverting urban exotic pine forests to Macchia and indigenous forest vegetation, using cable-yarders on the slopes of Table Mountain, South Africa
    (2003) Ackerman, P.; Talbot, B.
    This paper discusses some of the issues faced during the initial phases of a 12-year long project, which will ultimately result in the transformation of 53 ha of urban pine forests to a more diverse natural vegetation cover. Public sentiment, harvesting procedures and future management practices are addressed. The forests are currently managed for recreation and are a heavily utilised public amenity. Efforts have been made at every opportunity, to minimise disturbances to the recreational and biological capacity of the forest area. Public participation was encouraged at all stages, from a local to a national level. Harvesting operations were planned to make the transition from high open pine forest to mixed scrub Macchia and moist indigenous high forest as gradual, though complete, as possible within the given time frame. An aerial cable extraction system with a fixed skyline was applied in extracting the timber to minimise site impacts. Successful marketing of the timber together with the application of industrial harvesting technology meant that the project could be self-financing, which was an important prerequisite. Both public and vegetational response has been encouraging, and the inevitable, unforeseen problems and compromises, that have had to be met since project inception have been dealt with in an open and constructive participatory forum.