Publikasjoner
NIBIOs ansatte publiserer flere hundre vitenskapelige artikler og forskningsrapporter hvert år. Her finner du referanser og lenker til publikasjoner og andre forsknings- og formidlingsaktiviteter. Samlingen oppdateres løpende med både nytt og historisk materiale. For mer informasjon om NIBIOs publikasjoner, besøk NIBIOs bibliotek.
2013
Forfattere
Geir-Harald StrandSammendrag
There is a growing demand for reliable information about land cover and land resources. The Norwegian area frame survey of land cover and outfield land resources (AR18X18) is a response to this demand. AR18X18 provides unbiased land cover and land resource statistics and constitutes a baseline for studying changes in outfield land resources in Norway and a framework for a national land resource accounting system for the outfields. The area frame survey uses a systematic sampling technique with 0.9 km2 sample plots at 18 km intervals. A complete wall-to-wall land cover map of an entire plot surveyed is obtained in situ by a team of fieldworkers equipped with aerial photographs. The use of sample plots with extended coverage (0.9 km2) ensures that the survey also deals with local variation, thus strengthening the estimates well beyond simple point sampling. The article documents the methodology used in the survey, followed by a discussion of issues raised by the choice of methodology. These issues include the problem of calculating uncertainty and a confidence interval for the estimates, the focus on common rather than rare land cover categories, and the prospect of downscaling the results in order to obtain statistics for subnational regions.
Sammendrag
Old trees represent key features of old-growth forests and are important elements for maintaining biodiversity. Due to extensive human exploitation of Fennoscandian boreal forests during several centuries, old Norway spruce trees have become exceedingly rare. We analysed 91 spruce trees in Trillemarka Nature Reserve, southern Norway, to investigate (1) the maximum age of living trees, (2) growth rates of different-age trees and (3) growth trends in very old trees. Increment cores were taken from trees in selected old-growth stands located at 700–850 m a.s.l. Twelve spruce trees had an estimated total age of >400 years, the oldest one being 529 years and presumably the oldest known still living Norway spruce in northern Europe. A negative relationship between growth rate (basal area increment) and total age was observed, being most distinct for growth rates at 126–275 years and less marked for early stage growth (26–75 years). Thus, high age apparently was related more to low growth rates at adult and old stages of life rather than at the earlier stage. Among the trees >400 years, many of them did not show growth decrease with advancing age, indicating that ageing did not reduce growth. We conclude that the maximum age of stand-forming Fennoscandian Norway spruce trees would be in the range of 500–600 years.
Sammendrag
North European epiphytic lichens are often genetically impoverished compared with their North American counterparts. This has been hypothesized to impede sexual reproduction due to reduced chances of finding compatible mating type partners. We compared genetic variation and reproductive mode in two threatened Scandinavian lichens, Evernia divaricata and Usnea longissima, with more viable populations in North America to see (i) if these species also show genetical depletion in northern Europe and (ii) if the occurrence of sexual propagules (ascospores in apothecia) is more prevalent in genetically diverse populations. Genetic variation of the fungal component was assessed by sequencing two nuclear rDNA gene regions (ITS and IGS) in 1005 and 1477 thalli, collected from 92 and 160 localities of E. divaricata and U. longissima, respectively. Scandinavian populations of both species were almost devoid of genetic variation compared with much higher genetic diversity in North America.We found no support for the proposed relationship between genetic diversity and fertility. Fertile thalli were found in several genetically invariable populations. Fertility increased with population size and regional abundance in E. divaricata, but not in U. longissima. In Scandinavia, E. divaricata was more fertile than previously recorded, whereas all sampled populations of U. longissima were sterile and possibly clonal.
Forfattere
Hanne Larsen Eivind VangdalSammendrag
Det er ikke registrert sammendrag
Sammendrag
Det er ikke registrert sammendrag
Forfattere
Jutta Kapfer Harry John Betteley Birks Vivian Astrup Felde Kari Klanderud Tone Constance Martinessen Louise C. Ross Fride Høistad Schei Risto Virtanen John Arvid GrytnesSammendrag
Background: Studies quantifying and comparing the variation and degree of compositional stability of vegetation and what determines this stability are needed to better understand the effects of the projected climate change. Aims: We quantified long-term vegetation changes in different habitats in northern Europe by exploring changes in species co-occurrences and their links to diversity and productivity gradients. Methods: We re-sampled vegetation in 16 arctic, mountain, and mire sites 20 to 90 years after first inventories. A site-specific change in species assemblages (stability) was quantified using species co-occurrences. We tested if the observed changes were significantly greater than would be expected by chance using a randomisation test. Relationships between patterns in vegetation stability and time between surveys, numbers of plots, or species diversity and proxies for productivity were tested using regression analysis. Results: At most sites, changes in species co-occurrences of vascular plants and bryophytes were greater than expected by chance. Observed changes were not found to be related to gradients in productivity or diversity. Conclusions: Changes in species co-occurrences are not strongly linked to diversity or productivity gradients in vegetation, suggesting that other gradients or site-specific factors (e.g. land-use, species interactions) might be more important in controlling recent compositional shifts in vegetation in northern Europe.
Sammendrag
Tourism is acknowledged to be an important business sector in rural areas. This paper argues that second-home owners constitute an important market segment for businesses that offer nature-based tourism activities. Previous research has shown that a number of factors influence tourist behaviour. This study examined how motivation and demographic variables affect second-home owners’ intention to purchase three different types of activity products: learning, adventure, and hunting products.We found substantial variations in the purchase intentions for these products among second-home owners. These intentions were influenced by push and pull motivations, age, income and educational level. Secondhome owners with a high intention of purchasing nature-based tourism activity products tend to be young, high-income, and socially oriented risk takers. Businesses offering nature-based tourism activity products should use a combination of demographic and psychographic variables when they segment the second-home market.
Sammendrag
The relative frequency of Therrya fuckelii and T. pini fruiting on dead branches of Scots pine was investigated in southern Norway by examining lightning-damaged and wind-fallen trees, randomly collected branches and Nordic herbarium collections of these ascomycetes representing the order Rhytismatales. Ascus, ascospore, and subhymenium characteristics were used as criteria for species identification, while a sequence analysis of ITS rDNA gene cluster was performed to compare the relatedness of the species to each other and to corresponding fungal sequences available at the NCBI GenBank Sequence Database. In a few cases, the two Therrya species co-occurred on the same branch, but in general, whether field or herbarium material, T. fuckelii was clearly more common than T. pini.Within the Nordic countries, both species occurred throughout the natural distribution area of Scots pine. The ITS rDNA sequence of T. pini strains was 91% similar to T. fuckelii strains, the differences locating both within the internal transcribed spacers ITS1 and ITS2 and the 5.8 S rDNA gene. More variation in the ITS1-5.8S-ITS2 sequence was observed among T. pini than T. fuckelii samples; genetic implications of this finding are discussed. Upon sequence analysis, we discovered that a T. pini sequence has been deposited in the NCBI GenBank under a false identity. We emphasize the importance of co-examining strains that originate from mature fruit bodies with fully developed morphologic features as reference samples.
Forfattere
Hanne Sogge Thomas Rohrlack Trine Ballestad Rounge Jørn Henrik Sønstebø Ave Tooming-Klunderud Tom Kristensen Kjetill Sigurd JakobsenSammendrag
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Forfattere
Dominika Srednicka-Tober Marcin Baranski Joanna Gromadzka-Ostrowska Krystyna Skwarlo-Sonta Ewa Rembialkowska Jana Hajslova Vera Schulzova Ismail Cakmak Levent Ozturk Tomasz Krolikowski Katarzyna Wisniewska Ewelina Hallmann Elzbieta Baca Mick Eyre Håvard Steinshamn Teresa Jordon Carlo LeifertSammendrag
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