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.
2000
Authors
Per Holm Nygaard Heleen A. de WitAbstract
Elevated concentrations of aluminium (Al) which have been hypothesized to limit root growth of forest trees as well as nutrient uptake, are believed to be a major threat to forest vitality. Direct toxicity of Al, causing decreased root growth has been observed in several nutrient solut ion studies and in some pot experiments using seedlings.However, direct support for the occurrence of decreased root growth in mature forest stands is scarce. Despite the uncertainty concerning effects of ambient concentrations of Al in soil water on fine roots, the concentrations of dissolved Al in forest soils has been assigned a key role in models used to calculate critical loads.Here we present results of three years of artificial additions of Al on fine root growth in a mature stand of Norway spruce (Piece abies). During the growing season the average concentrations of dissolved inorganic in soil water at 10-cm soil depth ranged from about 1 mol L-1 (control) to 120 mol L-1 (highest Al treatment).According to nutrient solution studies the established concentrations of dissolved inorganic Al reached levels that may be toxic. In addition, the Ca/Al ratios were well below 1.0, a value, which is regarded as a lower limit below which negative effects on vegetation may be expected.So far, no effects on fine root growth, root mortality and root distribution has been observed. Chemical analysis of the fine roots indicate a lower molar Ca/Al ratio in living fine roots of 0-20 cm depth and dead fine roots 0-40cm in the Al treatments compared to controls.Our study does not support the critical load assumption that Ca/Al 1 in soil solution is critical to fineroots, as shown by some culture solution experiments. The molar Ca/Al ratio of fine roots mainly reflect the soil chemical composition, which has a steep depth gradient So far, three years of Al additions has shown that the soilmatrix is an extremely robust growth medium, which can sustain high inorganic Al concentration and low Ca/Al ratios.The results show clearly that the value of Ca/Al or BC/Al as used in critical load calculation and plant soil modeling, may have to be reconsidered.
Authors
Jan Mulder J.F. Gallardo Lancho E. Matzner Edward Tipping Charlotte Bryant Nicholas Clarke S. Lofts B. Michalzik A. Vicente EstebanAbstract
No abstract has been registered
Authors
Halvor TorgersenAbstract
This article describes an investigation of fatigue resistance in different steel wire rope constructions used in Norwegian cable logging operations. Test results indicate the following: A clear difference in fatigue resistance between ropes (approximately 50% decreased endurance for the compacted rope of highest density). Differences in rope wear for varying angles of deflection. A correlation between the number of visible broken wires and remaining strength in the rope.
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Authors
M.J. Latkowska Harald Kvaalen M. AppelgrenAbstract
The influence of light quality on the proliferation of embryogenic tissue of three genotypes of Norway spruce (Picea abies [L.] Karst), with different capacities for mature somatic embryo production, was studied.The proliferating tissues were subjected to light from commercially available light sources: Philips TLD Warm White 36W/29, Philips TLD Blue 18W/18, Philips TLD Red 36W/15, Osram L Fluora 36W/77 and Sylvania Far Red 7080, for 18 h a day with the photon flux (PAR) at 30 mol m-2 s-1.The effect of light quality on the growth of embryogenic tissue was strongly genotype dependent. In genotype 164-4 tissue proliferation was strongly inhibited by blue and red light. Genotype 86:52 reacted in a similar way, but not as strongly as 164-4, whereas the tissue of genotype 186-3 was almost insensitive to light quality and grew fast in all light conditions.
Authors
A. Sæbø Øystein JohnsenAbstract
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Authors
Staffan Jacobson Mikko Kukkola E. Mälkönen Bjørn TveiteAbstract
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Authors
V.R. Nsolomo Halvor Solheim Kåre Olav VennAbstract
No abstract has been registered