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.
2015
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John Arvid Grytnes Vivian Astrup Felde Hanne Henriksen Jutta Kapfer Kari Klanderud Mikael Ohlson Fride Høistad Schei Richard James Telford Risto VirtanenAbstract
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Tuva Grytli Geoffrey Guest Carine Lausselet Francesco Cherubini Ryan Bright Per Kr. Rørstad Helmer Belbo Rasmus Astrup Øyvind Skreiberg Morten Seljeskog Franziska Goile Anders Hammer StrømmanAbstract
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Safaa Wasof Jonathan Lenoir Per Arild Aarrestad Inger Greve Alsos W. Scott Armbruster Gunnar Austrheim Vegar Bakkestuen Harry John Betteley Birks Kari Anne Bråthen Olivier Broennimann Jörg Brunet Hans Henrik Bruun Carl Johan Dahlberg Martin Diekmann Stefan Dullinger Mats Dynesius Rasmus Ejrnæs Jean-Claude Gegout Bente Jessen Graae John-Arvid Grytnes Antoine Guisan Kristoffer Hylander Ingibjørg Jonsdottir Jutta Kapfer Kari Klanderud Miska Luoto Ann Milbau Mari Moora Bettina Nygaard Arvid Odland Harald Pauli Virve Ravolainen Stefanie Reinhardt Sylvi Marlen Sandvik Fride Høistad Schei James David Mervyn Speed Jens-Christian Svenning Wilfried Thuiller Unn Tveraabak Vigdis Vandvik Liv Guri Velle Risto Virtanen Pascal Vittoz Wolfgang Willner Thomas Wohlgemuth Niklaus E Zimmermann Martin Zobel Guillaume DecocqAbstract
Aim Previous research on how climatic niches vary across species ranges has focused on a limited number of species, mostly inv asive, and has not, to date, been very conclusive. Here we assess the degree of niche conservatism between distant populations of native alpine plant species that have been separated for thousands of years. Location European Alps and Fennoscandia. Methods Of the studied pool of 888 terrestr ial vascular plant species occurring in both the Alps and Fennoscandia, we used two complementary approaches to test and quantify climatic-niche shifts for 31 species having strictly disjunct populations and 358 species having either a contiguous or a patchy distribution with distant populations. First, we used species distr i- bution modelling to test for a region effect on each species’ climatic niche. Second, we quantified niche overlap and shifts in niche width (i.e. ecological amplitude) and position (i.e. ecological optimum) within a bi-dimensional climatic space. Results Only one species (3%) of the 31 species with str ictly disjunct populations and 58 species (16%) of the 358 species with distant popula- tions showed a region effect on their climatic niche. Niche overlap was higher for species with strictly disjunct populations than for species with distant populations and highest for arctic–alpine species. Climatic niches were, on average, wider and located towards warmer and wetter conditions in the Alps. Main conclusion Climatic niches seem to be generally conserved between populations that are separated between the Alps and Fennoscandia and have probably been so for 10,000–15,000 years. Therefore, the basic assumption of species distribution models that a species’ climatic niche is constant in space and time – at least on time scales 10 4 years or less – seems to be largely valid for arctic–alpine plants.
2014
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Nils Egil SøvdeAbstract
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Nils Egil SøvdeAbstract
Ground based systems are the main approach used for off-road timber transportation throughout the world. Estimates of terrain transportation costs are required for several forest planning problems and for assessment of harvesting contracts and forest land values. Methods for these calculations can be categorized into two groups. Methods based on average transportation distance predate computers, are analytical, and based on manual calculations. Network methods are based on a digital raster representation and are solved with numerical computations. Here, the two categories are compared and linked. Analytical methods in the literature have been limited to flat terrain and including detail is difficult. The network method can be extended to include uneven terrain or detailed input data.
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