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.
2013
Sammendrag
No abstract has been registered
Sammendrag
In Norway, water quality of small streams draining agricultural catchments has been monitored since 1993 by the Agricultural and Environmental Monitoring Program. This article attempted to examine the concentration levels, temporal dynamics and long-term trends (1993–2009 and 1996–2009) of Al, Fe, Cu, Mn and Zn in streams draining the catchment areas of Skuterud (4.5 km2) and Mørdre (6.8 km2), located in south-east Norway. In the Mørdre stream, Al, Fe, Cu, Mn and Zn all showed statistically significant downward trends (p<0.05), whilst in the Skuterud stream only Al and Fe showed statistically downward significance (p<0.05). The general declining trends of metal concentrations are most likely associated with reduction of acid rain deposition in southern Norway. In spite of this declining trends, over the 14–17 years of monitoring mean monthly concentrations of total Al (2.0–3.2 mg L−1), Fe (1.3–2.5 mg L−1) and Cu (8.9–26.1 µg L−1) in Skuterud and Mørdre streams, respectively exceeded the limits of the Norwegian Water Framework Directives, whereas the concentrations of Mn (22.3–40.8 µg L−1) and Zn (13.1–99.4 µg L−1) fell within the range of desired limits. Of the total water samples analysed from Skuterud (n=370) and Mørdre streams (n=255), nearly 80–84%, 70–87% and 79–96% were above the desired limits for Al (0.2 mg L−1), Fe (0.3 mg L−1) and Cu (3 µg L−1), respectively. In 2011, water analysis from drainage of forest soils (in Skuterud catchment) measured total Al: 0.42–0.79 mg L−1 and total Fe: 0.84–1.0 mg L−1 which were two to three folds greater than the desired limits. In general, weak correlations between runoff and concentrations of the metals in the streams were noted. Future research should focus on identifying the sources of Al, Fe and Cu and management interventions of elevated metal inputs to Skuterud and Mørdre streams.
Forfattere
Karl Henrik Haugholt Matthieu Jean P Lacolle Marion O'Farrell Atle Honne Kari Anne Hestnes Bakke Aina Lundon RussenesSammendrag
A low-cost Fourier transform infrared (FTIR) instrument was developed where the traditional He–Ne reference laser was replaced by a low-cost linear encoder. An RMS sampling error of less than 20 nm was achieved by oversampling both the interferogram and the encoder signal and then resampling the interferogram using a correction table for the encoder. A gas calibration model was developed for the system, which was chosen to have a stroke length of 21 mm and, thereby, a resolution of 0.4 cm −1 after apodization. The instrument was mounted on a vehicle and employed in an agricultural field test for measuring soil emissions, in particular nitrous oxide (N 2 O ). The concentration of N 2 O was measured with a root mean squared error of 6 ppb. The results compared well with lab-based gas chromatography measurements.
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
No abstract has been registered
Sammendrag
No abstract has been registered
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.