Publications
NIBIOs employees contribute to several hundred scientific articles and research reports every year. You can browse or search in our collection which contains references and links to these publications as well as other research and dissemination activities. The collection is continously updated with new and historical material.
2016
Authors
Tuva Grytli Geoffrey Guest Carine Lausselet Francesco Cherubini Per Kr. Rørstad Helmer Belbo Rasmus Astrup Øyvind Skreiberg Morten Seljeskog Franziska Goile Anders Hammer StrømmanAbstract
No abstract has been registered
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Authors
Jutta Kapfer Radim Hédl Gerald Jurasinski Martin Kopecký Fride Høistad Schei John-Arvid GrytnesAbstract
Background: Resurveying historical vegetation plots has become more and more popular in recent years as it provides a unique opportunity to estimate vegetation and environmental changes over the past decades. Most historical plots, however, are not permanentlymarked and uncertainty in plot location, in addition to observer bias and seasonal bias, may add significant errors to temporal change. These errorsmay havemajor implications for the reliability of studies on long-term environmental change and deserve closer attention of vegetation ecologists. Methods: Vegetation data obtained from the resurveying of non-permanently marked plots are assessed for their potential to study environmental change effects on plant communities and the challenges the use of such data have to meet. We describe the properties of vegetation resurveys, distinguishing basic types of plots according to relocation error, and we highlight the potential of such data types for studying vegetation dynamics and their drivers. Finally, we summarize the challenges and limitations of resurveying non-permanently marked vegetation plots for different purposes in environmental change research. Results and conclusions: Re-sampling error is caused by three main independent sources of error: error caused by plot relocation, observer bias and seasonality bias. For relocation error, vegetation plots can be divided into permanent and non-permanent plots, while the latter are further divided into quasi-permanent (with approximate relocation) and non-traceable (with random relocation within a sampled area) plots. To reduce the inherent sources of error in resurvey data, the following precautions should be followed: (i) resurvey historical vegetation plots whose approximate plot location within a study area is known; (ii) consider all information available from historical studies in order to keep plot relocation errors low; (iii) resurvey at times of the year when vegetation development is comparable to the historical survey to control for seasonal variability in vegetation; (iv) retain a high level of experience of the observers to keep observer bias low; and (v) edit and standardize data sets before analyses.
Abstract
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2015
Abstract
The Cableway Location Problem (CLP) is a facility location problem usually studied as a part of a hierarchical approach for large cable yarding systems outside of Europe. Small adaptable cable yarding systems are used in Europe. This increases the number of possible landing sites and makes the layout problem hard to solve to optimality. Here, two approaches are presented that solve the novel European CLP (E-CLP). The methods are tested on several generated cases and one real world case. The lateral yarding distance is introduced in the cost calculations to improve the quality of the solutions.
Authors
Nils Egil SøvdeAbstract
Cable yarding systems are commonly used in steep or difficult terrain and require suitable landing sites. This work describes two algorithms that calculate the suitability of roads and areas for landing site use. The algorithms were tested against real world data. The results show that simple algorithms are sufficient to make stable, useful estimates that are comparable with human site placements. These techniques can be used to guide forest road network planning or reuse of existing roads.
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No abstract has been registered
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No abstract has been registered
Abstract
No abstract has been registered