Cable Yarding in North America and New Zealand: A Review of Developments and Practices

Cable yarders have been an integral part of harvesting timber on steep terrain for over 150 years. They have developed from basic labour intensive steam powered winch operations to sophisticated and automated mechanised systems. While European yarder development has focused on relatively small but highly mobile machines operating with standing skyline configurations, the North American and Southern Hemisphere developments have tended towards larger, taller and more powerful machines capable of higher daily production. Two dominant North American brands, Madill and Thunderbird, produced over 3000 yarders and many of their machines continue to work today. Often working with 4 or 5 drums, they were able to develop and utilise an expansive range of rigging configurations to suit different extraction needs. Modern developments continue to focus on increasing production capability and cost-effectiveness suited to clear-cut plantation forestry. With safety becoming more paramount in terms of a licence to operate, a strong preference is given to fully mechanised systems. By definition, these are yarders with rigging systems that support grapple carriages, extracting timber that has been mechanically felled on steep slopes. While mechanical grapple carriages have long been combined with swing yarder systems, the further development of a motorised grapple carriage allows tower yarders to operate without choker-setters. Ergonomic improvements for the operator, long established in European machinery, are being integrated including cab design with greatly improved visibility and partially automated electric over hydraulic control systems. Logic would suggest that, over time, yarder developments will combine the strength and robustness of North American design and the finesse and automation of European design. However, recent machine sales in North America and New Zealand continue to show a clear difference with the preference of large swing yarders capable of running fully mechanised extraction systems

The impact of residents' informedness and involvement on their perceptions of tourism impacts: The case of Bled

The tourism development debate includes many studies on how residents perceive positive or negative tourism impacts, based on sustainability, as understood by a three-pillar concept. However, so far studies were very limited in addressing certain requirements for sustainable tourism, such as informed stakeholders’ participation and cooperation – which represent the subject of this study. The survey that was undertaken follows previous ones in using the established three-pillar sustainability concept in order to define impacts of tourism. Further, it adds to tourism research by surveying informedness and developmental involvement. A four-dimensional informedness–involvement tourism grid is used to segment residents and their perceptions on tourism impacts in each segment are analysed. The model is empirically applied to the Slovenian lake and mountain destination of Bled. The findings confirm that highly informed and highly involved residents had better perceptions of tourism than all other groups, whereas those residents who were lowly informed and lowly involved had more negative perceptions of tourism. The survey contributes by expanding knowledge on resident perceptions of tourism by adding in the aspects of informedness and involvement. The proposed model can be applied to any destination to help manage residents’ opinions and consequently their support for tourism development

Improving Cable Logging Operations for New Zealand’s Steep Terrain Forest Plantations

Cable logging will become more important as harvesting shifts to greater annual proportions on steep terrain in New Zealand. The costs of cable logging are considerably higher than that of conventional ground-based methods. Improving cost-effectiveness has been identified as key to ensuring the forestry industry remains cost competitive in the international market. This thesis focuses on ways to better understand and improve cable logging methods by specifically focusing on rigging configurations. The investigation was conducted through a comprehensive literature review, an industry survey to establish current use and preferences, a Delphi survey with experts to establish actual advantages and disadvantages, scale model testing to establish some fundamental knowledge of tension to deflection relationship, and finally a series of targeted case studies to establish both productivity and skyline tension in actual operations. Each of these aspects of the research topic employed different methodology. The literature review highlighted the most relevant research relating to cable logging world-wide spanning nearly a century. Various research papers, manuals, books and computer software were summarized. While many aspects of cable yarding operations have been investigated, much of it focusing on various aspects of operational efficiency through case studies, there is very limited information with regard to rigging configurations. The survey of 50 cable logging practitioners determined what rigging configurations were commonly used in New Zealand. It includes their perceived advantages and disadvantages for varying levels of deflection, but also for specific scenarios such as pulling away from native forest boundaries and flying logs over a stream. Results showed that there were many conflicting perceptions about rigging configuration options. Using an expert panel, a Delphi process was used to derive consensus on what advantages were truly unique to each configuration. This allowed the longer lists of perceived advantages from the industry survey to be pared down to a concise list of ad/disadvantages that will be used in the updating of the Best Practice Guidelines for Cable Logging. To increase our fundamental understanding of tension / payload / deflection relationships, an experiment was conducted in a controlled environment. Using a model yarder in a lab and continuous tension and video recording devices, the dynamic skyline behavior of three similar configurations were tested: North Bend, South Bend and Block in the Bight. The tensions were compared by use of a two-way analysis of variance, which indicated configuration and choker length were significant variables in some but not all of the dynamic load tests. Results also showed that some configurations performed better than others in minimizing the shock loads due to dropping into full suspension, impact with ground objects, and breakout during bridling. Finally, a series of eight studies were conducted on targeted logging operations where relevant stand and terrain parameters were related to the continuous skyline tension monitoring, and recording of productivity through time study. The three targeted configurations included (1) North Bend, (2) Standing skyline using a motorized slack-pulling carriage and (3) a live skyline using a motorized grapple carriage. Results showed that peak and average tensions, as well as amplification factors and the payload to tension relationship, varied between configurations. The study also showed that tensions could be collected to compute measures of payload and tension efficiency, which provided insight into operational performance. The safe working load was exceeded in 53% of all cycles studied and across seven of eight study sites and 14 of 16 spans. Cycle times were significantly different between rigging configurations and that production information could be used to compute measures of labor and energy consumption as well as payload and tension efficiency; which also provide insight into operational performance. The industry should give serious consideration to the use of tension monitors. Tension monitors have many benefits and have the potential to improve cable logging operations in New Zealand. Monitoring tensions can help one learn new techniques or methods (i.e. rigging configurations), help improve payload analysis software for future planning and help evaluate new technology and machinery

Operational Analysis of Grapple Yarding in New Zealand: A Case Study of Three Mechanized Harvesting Operations

The New Zealand forest industry has increased its use of swing yarders when harvesting on steep slopes. Swing yarders can more readily operate with grapple carriages, both mechanical and motorized, in comparison to tower yarders. Especially when coupled with mechanized felling, grapple yarding has led to improved productivity and safety. The effective use of grapple yarding is dependent on the level of knowledge of the working capability of the machines. This productivity study analyzed the operational capability of grapple yarding at three different harvest sites in North Island, New Zealand. The swing yarders were the T-Mar 650, T-Mar 550, and Madill 124 models. Parameters including average piece size, extraction distance, turn volume and the number of pieces were recorded for each cycle, as well as the level of bunching, with a minimum of 125 cycles, were measured at each site. The average delay-free cycle time for the three sites ranged between 2.8 and 3.7 min, which is very fast compared to yarder operations using chokers. Productivity ranged from 50 to 55 tons per productive machine hour. Extraction distance, piece size and stem presentations significantly influenced productivity. Stem presentation, especially bunching, across the cutover influenced the mean payload per yarding cycle resulting in higher productivity. In addition to providing productivity capability information at three case study sites, the analyses linked stand and terrain parameters such as tree size and extraction distance with production variability. Managing variability is critical to achieving consistently higher rates of production efficiency

Using Conjoint Analyses to Improve Cable Yarder Design Characteristics: An Austrian Yarder Case Study to Advance Cost-Effective Extraction

Steep country harvesting has been identified as the main bottleneck to achieving greater profitability in the forestry sector of New Zealand and Australia. An improvement of efficiency, work safety and environmental sustainability should be realized by developing an advanced steep terrain timber harvesting system based on innovative Austrian technology. To identify the best suitable configuration of a cable yarder for steep terrain harvesting, user preferences based on an online survey (conjoint analysis) have been evaluated to answer the following questions: (1) What attributes of a new yarder design are most important to consumers? (2) Which criteria do stakeholders consider when selecting a cable yarder? (3) What are the weights representing the relative importance of criteria? Using eight specific design scenarios a fourth question, being which cable yarder concept is the best, was also answered. This case study shows that conjoint analyses is an effective tool to assess, rate and subsequently integrate design characteristics. Based on the results of the analysis, a cable yarder prototype will be manufactured in Austria and transferred to New Zealand for testing and demonstration

A Multi-Megabase Copy Number Gain Causes Maternal Transmission Ratio Distortion on Mouse Chromosome 2

<div><p>Significant departures from expected Mendelian inheritance ratios (transmission ratio distortion, TRD) are frequently observed in both experimental crosses and natural populations. TRD on mouse Chromosome (Chr) 2 has been reported in multiple experimental crosses, including the Collaborative Cross (CC). Among the eight CC founder inbred strains, we found that Chr 2 TRD was exclusive to females that were heterozygous for the WSB/EiJ allele within a 9.3 Mb region (Chr 2 76.9 – 86.2 Mb). A copy number gain of a 127 kb-long DNA segment (designated as responder to drive, <i>R2d</i>) emerged as the strongest candidate for the causative allele. We mapped <i>R2d</i> sequences to two loci within the candidate interval. <i>R2d1</i> is located near the proximal boundary, and contains a single copy of <i>R2d</i> in all strains tested. <i>R2d2</i> maps to a 900 kb interval, and the number of <i>R2d</i> copies varies from zero in classical strains (including the mouse reference genome) to more than 30 in wild-derived strains. Using real-time PCR assays for the copy number, we identified a mutation (<i>R2d2^WSBdel1</i>) that eliminates the majority of the <i>R2d2^WSB</i> copies without apparent alterations of the surrounding WSB/EiJ haplotype. In a three-generation pedigree segregating for <i>R2d2^WSBdel1</i>, the mutation is transmitted to the progeny and Mendelian segregation is restored in females heterozygous for <i>R2d2^WSBdel1</i>, thus providing direct evidence that the copy number gain is causal for maternal TRD. We found that transmission ratios in <i>R2d2^WSB</i> heterozygous females vary between Mendelian segregation and complete distortion depending on the genetic background, and that TRD is under genetic control of unlinked distorter loci. Although the <i>R2d2^WSB</i> transmission ratio was inversely correlated with average litter size, several independent lines of evidence support the contention that female meiotic drive is the cause of the distortion. We discuss the implications and potential applications of this novel meiotic drive system.</p></div