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.
2011
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The Ritland structure is a newly discovered impact structure, which is located in southwestern Norway. The structure is the remnant of a simple crater 2.5 km in diameter and 350 m deep, which was excavated in Precambrian gneissic rocks. The crater was filled by sediments in Cambrian times and covered by thrust nappes of the Caledonian orogen in the Silurian–Devonian. Several succeeding events of uplift, erosion, and finally the Pleistocene glaciations, disclosed this well-preserved structure. The erosion has exposed brecciated rocks of the original crater floor overlain by a thin layer of melt-bearing rocks and postimpact crater-filling breccias, sandstones, and shales. Quartz grains with planar deformation features occur frequently within the melt-bearing unit, confirming the impact origin of the structure. The good exposures of infilling sediments have allowed a detailed reconstruction of the original crater morphology and its infilling history based on geological field mapping.
Abstract
Understanding the driving forces affecting species occurrences is a prerequisite for determining the indicator suitability of crenic plants. We analysed 18 environmental variables in a two-step approach, evaluating their ability to explain the species composition of 222 springs on five siliceous mountain ranges, in central Germany and north-west Czech Republic (49.9°–50.8°N, 10.6°–12.8°E). First, we identified the significant environmental variables in three subsets of spatial, hydrophysical and hydrochemical variables using a forward-selection procedure. We then performed a partial canonical correspondence analysis (pCCA) to estimate the influence of each subset alone, as well as in combinations. We also used a multiple response permutation procedure (MRPP) to compare the five regions with respect to the dissimilarity of their vegetation composition and environmental variables. Hydrochemical factors played a fundamental role in determining the plant community of the investigated springs. Spatial factors, in particular altitude, were correlated with the hydrochemical factors, but were less important. Hydrophysical factors played only a marginal role. More precisely, species occurrence was mainly driven by a gradient of nutrient availability, which in turn reflected the acidity status. This gradient was primarily represented by high Al, Cd, and Mn concentrations in acidic crenic waters, high Ca and Mg concentrations were encountered in circumneutral springs. By comparing the five regions we could show that there are spatial patterns in the vegetation of springs, which provide valuable ecological information on the water quality. We therefore suggest that biomonitoring approaches to vegetation are suitable for revealing the acidity status of springs and their forested catchments.
Authors
Clemens Reimann Tor Erik Finne Øystein Nordgulen Arnold Arnoldussen Peter EnglmaierAbstract
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Arild AndersenAbstract
Preliminary results from a Norwegian research project 2005-2008 on Arion lusitanicus was presented. In private gardens handpicking had the strongest effect on the population size, but creating relatively dry and open gardens, and removing suitable overwintering sites also had effect. The geographic distribution and life cycle are also presented. Foreløpige resultater fra et norsk forskningsprosjekt 2005-2008 på Iberiaskogsnegl ble presentert. I privathager hadde håndplukk den sterkeste effekten på populasjonsstørrelsen, men også det å skape relativt tørre og åpne hager, og å fjerne gunstige overvintringssteder hadde effekt. Artens utbredelse og livssyklus i Norge ble også presentert.
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Authors
Bernt-Håvard ØyenAbstract
Removal of up to 40-50 % of the total volume production by successive thinning from early age seems to have a positive effect on the yield of fresh wood in stands of Norway spruce. In young stands there is a decrease of yield caused by early, heavy thinning. The stands are usually stable and healthy. Low oriented and moderate thinning operations do not appear to influence the yield situation in general, although culmination is prolonged. Also in Central Norway difficult access to the forests, lack of roads, high labour costs and sometimes low initial densities moderate the present interest for thinning.
Abstract
No abstract has been registered