8 results on '"Maarten Nieuwenhuis"'
Search Results
2. Stem quality assessment using terrestrial laser scanning technology: a case study of ash trees with a range of defects in two stands in Ireland
- Author
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Michael Hawkins, Maarten Nieuwenhuis, Taye Mengesha, and Mark Tarleton
- Subjects
Fraxinus excelsior L ,Quality assessment ,Range (statistics) ,Environmental science ,Forestry ,Terrestrial laser scanning ,Agricultural engineering - Abstract
Information on stem quality of standing (broadleaf) timber is of great importance to the forestry sector to help optimise harvesting and marketing strategies. Manual assessment of such quality parameters in standing trees is extremely difficult, time consuming and costly. The objectives of this study were therefore to assess stem quality parameters such as taper, lean and sweep in ash (Fraxinus excelsior L.) stands, during leaves-on and leaves-off conditions, using terrestrial laser scanning technology, and to compare the estimated parameters with manually measured values in a mature and young stand. Diameter estimation was more accurate during the leaves-off condition in both stands, resulting in taper estimates that were closer to the manually obtained values as well. However, in general, the taper values did not match those obtained manually very closely. Given that the sample trees were chosen deliberately to include noticeable defects such as non-circularity, bending, swellings, knots resulting from ...
- Published
- 2015
- Full Text
- View/download PDF
3. The role of knowledge, attitudes and perceptions in the uptake of agricultural and agroforestry innovations among smallholder farmers in sub-Saharan Africa
- Author
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Oluyede C. Ajayi, Maarten Nieuwenhuis, Gudeta W. Sileshi, Delia Catacutan, and Seline S. Meijer
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Economics and Econometrics ,Sub saharan ,Potential adopter ,Agroforestry ,Agriculture ,business.industry ,Perception ,media_common.quotation_subject ,Sustainability ,business ,Agronomy and Crop Science ,media_common - Abstract
Despite the great potential of agricultural innovations, the uptake by smallholder farmers in sub-Saharan Africa seems to be slow. We reviewed existing theories and frameworks for the uptake of agricultural innovations and found that these tend to emphasize the role of extrinsic factors such as the characteristics of the adopter and the external environment in the decision-making process. In this paper, we argue that intrinsic factors such as the knowledge, perceptions and attitudes of the potential adopter towards the innovation play a key role, but this has been less studied. We present an analytical framework that combines both extrinsic and intrinsic factors in farmers' decisions to adopt new agricultural technologies and apply the framework to agroforestry adoption as a case study. We review the literature on agroforestry adoption in sub-Saharan Africa and identify the extrinsic and intrinsic variables affecting the uptake of agroforestry technologies. We conclude that the uptake of agricultural tech...
- Published
- 2014
- Full Text
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4. The Effect of Calibration on the Accuracy of Harvester Measurements
- Author
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Maarten Nieuwenhuis and Tadhg Dooley
- Subjects
Accuracy and precision ,Length measurement ,Engineering ,business.industry ,Volume measurement ,System of measurement ,Calibration ,Electronic engineering ,Point (geometry) ,Head measurements ,business ,Computerized measurement ,Remote sensing - Abstract
Almost all timber in Ireland is harvested using mechanical harvesting heads. All new harvesters come equipped with computerized measurement systems. The objective of the research reported in this article was to assess the impact of calibration on the accuracy of harvester head measurement systems in Irish forestry conditions. The research was carried out on a site in Co. Cork. The harvester was a Timberjack 1270D with a 762C harvester head and the Timbermatic 300 control and measurement system. The harvester measurement system was assessed on its accuracy in measuring the length and volume of individual stems and logs in 9 check runs of 7 or 8 stems. The harvester head measurements were compared to values obtained by caliper-and-tape measurements. The main point that can be taken from this research is that regular calibration will greatly improve the accuracy of the harvester measurement system. After calibration, length measurement by the harvester measurement system of individual logs was very accurate, while volume measurement was unsatisfactory for the pulp log assortment. The differences between the harvester measurements and the caliper-and-tape measurements fluctuated greatly, varying from positive to negative differences within a check run, even after calibration. These fluctuations could indicate an inherent problem associated with the design of the calibration procedure, as the positive and negative differences cancel each other out and the calibration, based on mean values, appears to indicate accurate measurements. More work needs to be done on reducing to impact of the roughness and branchiness of smaller dimension logs on the accuracy of diameter and length measurements in Irish conditions.
- Published
- 2006
- Full Text
- View/download PDF
5. Health and Safety Issues and Perceptions of Forest Harvesting Contractors in Ireland
- Author
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Marianne Lyons and Maarten Nieuwenhuis
- Subjects
Engineering ,business.industry ,media_common.quotation_subject ,Forest harvesting ,Forwarder ,Training level ,Occupational safety and health ,language.human_language ,Health problems ,Irish ,Work (electrical) ,Perception ,language ,Operations management ,business ,media_common - Abstract
The aim of this study was to examine the extent and severity of accidents and long-term health problems, and to evaluate perceptions of health and safety issues among forest harvesting contractors and sub-contractors in Ireland. A postal questionnaire was distributed to 450 forest harvesting (sub)contractors with the co-operation of the Irish Forestry Contractors Association (IFCA) and Coillte Teoranta (the State Forestry Company, referred to as Coillte). The questionnaire was completed and returned by 61 respondents. The majority of these were chainsaw, harvester and forwarder operators. The occurrence of an accident (requiring medical attention) in the last three years was reported by two respondents, while long-term health problems were reported by 23 (40%) of the respondents. Results showed that long-term health problems were not significantly correlated to age or training level. The two work elements in forest harvesting operations that were found to be most hazardous were operating a chainsaw and machine maintenance. When asked about the perceived dangers in the industry and the obstacles to improvements, 59% of the respondents identified harvesting work as dangerous, while 62% described financial pressure as the main barrier to improvements in safety, followed by the pressure of work (39%) and a lack of adequate training (36%). Suggestions on ways to improve the overall health and safety situation within forest harvesting included improved training and safety education (45%) and reduced work pressure (36%).
- Published
- 2002
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6. An Evaluation and Comparison of Mechanised and Manual Tree Planting on Afforestation and Reforestation Sites in Ireland
- Author
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Declan Egan and Maarten Nieuwenhuis
- Subjects
Root trainer ,Engineering ,Plant growth ,business.industry ,Tree planting ,Afforestation ,Reforestation ,Sowing ,Growing season ,Forestry ,Economic shortage ,business - Abstract
Recent labour shortages and rapid increases in labour costs in Irish forestry have directed attention to mechanised, containerised tree planting systems as an alternative to the traditional manual planting of bare-rooted stock. The objective of this study was to compare mechanised planting with manual operations, on both reforestation and afforestation sites, using Sitka spruce ( Picea sitchensis (Bong.) Carr.) plants in three container types (i.e. hard container, root trainer, fen container). The Bracke tree planting machine was selected for the study, as it is capable of handling a wide range of site conditions and a variety of plant types and sizes. A qualitative analysis of the collected data showed that, in general, manual planting scored significantly higher than mechanised planting for plant position and planting quality. However, the quality of planting resulting from mechanised operations was well within acceptable operational requirements. On the reforestation site, plant growth after one growing season was investigated. No overall significant differences in height growth and root collar diameter increment were found in the first growing season between mechanised and manual planting operations. Plants grown in `fen containers' had the highest relative increase in height growth and root collar diameter, irrespective of planting method. The results showed that the Bracke planting machine was capable of planting a range of containerised plants to an acceptable standard on both reforestation and afforestation sites. Further research to optimise the combination of machine, plant size and container type should result in improvements in both the quality and productivity of the planting operations.
- Published
- 2002
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7. Vegetative Propagation ofEucalyptus nitensUsing Stem Cuttings
- Author
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Nchemo Maile and Maarten Nieuwenhuis
- Subjects
Root formation ,Peat ,Vegetative reproduction ,Forestry ,Plant Science ,Vermiculite ,Biology ,biology.organism_classification ,Eucalyptus ,Cutting ,Horticulture ,Botany ,Eucalyptus nitens ,Woody plant - Abstract
SYNOPSIS Eucalyptus nitens (Deane & Maiden) Maiden is an economically important Eucalyptus species with a broad natural range in Australia and has been identified as a priority fuelwood plantation species in Lesotho. Unlike most eucalypts, E. nitens is a shy seed bearer. This study was aimed at propagating Eucalyptus nitens using stem cuttings. These were taken seasonally from an 11-year-old E. nitens stand and three-year-old stock plants. Cuttings were prepared in a factorial combination of four types of media (viz. peat, sand, vermiculite and a 1:1:1 mixture of the three) and two hormone dipping treatments (viz. no dipping and dipping in Seradix No. 3 rooting powder containing 0,8% IBA). In the last experiment, 0,2% IBA was used. Rooting performance was evaluated under glasshouse conditions using a warm bench propagation unit. Adventitious root formation on cuttings of E. nitens was not effectively influenced by the application of IBA. Rooting of cuttings obtained from 11-year-old E. nitens decreased fr...
- Published
- 1996
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8. Integrated Timber Allocation and Transportation Planning in Ireland
- Author
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Maarten Nieuwenhuis and G. Williamson
- Subjects
Transportation planning ,Geographic information system ,Water transport ,Operations research ,business.industry ,Wood processing ,Information system ,Economics ,Mandate ,Mill ,Environmental economics ,business ,State forest - Abstract
Coillte Teoranta, the Irish Forestry Board, was established as a forestry company in 1989, with a mandate to operate in forestry and related activities in a commercial manner. The company took over the assets of the state Forest Service and now owns and manages approximately 400,000 ha of forest. Coillte harvests and sells timber to the private wood processing industries in Ireland. Coillte harvested approximately 1.4 million m3 of timber in 1990. By 2010 this annual harvest volume will increase to 3.5 million m3. In order to manage the harvesting and transportation operations efficiently, a national timber sales allocation procedure was developed by the Forestry Department of University College, Dublin. The procedure uses Coillte's databases on harvest volumes, subdivided into supply categories; on mill demands, specified by demand categories; and on the national transportation network, including road, rail and water transport modes. The developed operational procedure was used as a decision-making tool during the allocation of the 1991 sales volumes. A comparison of the actual versus the optimized 1990 allocation strategy identified opportunities for large-scale savings. In addition to its main function as a decision-making tool for the annual sales allocation, the model has been used for other strategic and tactical planning analyses, such as the influence of new mill location on transport costs, the impacts of a timber processing industry rationalization programme on the industry as a whole and on individual mills, the feasibility of timber transport by rail, the selection of suitable ports for timber export, and the impact of road construction and improvement programmes on national timber transport strategies. The model has been successfully linked with the company's ARC/ INFO Geographic Information System which extends the post-allocation analysis and interpretation capabilities, and combines the output with existing information systems. A further integration of the procedure in the management decision-making processes in the company will result in increased cost saving opportunities.
- Published
- 1993
- Full Text
- View/download PDF
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