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.
2005
Sammendrag
Considerable knowledge exists about the effect of aluminium (Al) on root vitality, but whether elevated levels of Al affect soil microorganisms is largely unknown. We thus compared soils from Al-treated and control plots of a field experiment with respect to microbial and chemical parameters, as well as root growth and vitality. Soil from a field experiment established in a 50 year old Norway spruce (Picea abies L.) stand where low concentrations of aluminum (0.5 mM AlCl3) had been added weekly or bi-weekly during the growth season for seven years was compared to a control treatment with respect to microbial and chemical parameters, as well as root growth and vitality. Analysis of soil solutions collected using zero tension lysimeters and porous suction cups showed that Al treatment lead to increased concentrations of Al, Ca and Mg and lower pH and [Ca+Mg]/[Al] molar ratio. Corresponding soil analyses showed that soil pH remained unaffected (pH 3.8), that Al increased, while extractable Ca and Mg decreased due to the Al treatment. Root ingrowth into cores placed in the upper 20 cm of the soil during 28 months was not affected by Al additions, neither was the mortality of these roots. The biomass of some taxonomical groups of soil microorganisms in the humus layer, analyzed using specific membrane components (phospholipid fatty acids; PLFAs), was clearly affected by the imposed Al treatment, but less so in the underlying mineral soil. Microbial community structure in the humus layer was also clearly modified by the Al treatment, whereas differences in the mineral horizon were less clear. Shifts in PLFA trans/cis ratios indicative of short term physiological stress were not observed. Yet, aluminium stress was indicated both by changes in community structure and in ratios of single PLFAs for treated/untreated plots. Thus, soil microorganisms were more sensitive indicators of subtle chemical changes in soil than chemical composition and vitality of roots.
Sammendrag
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Forfattere
Päivi Rinne Carl Gunnar Fossdal Sissel Torre Heather Danforth Aksel Granhus Gunnhild Søgaard John Einset Harald Kvaalen Øystein Johnsen Chris Van der SchootSammendrag
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Sammendrag
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2004
Forfattere
Lars Sandved Dalen Heather Danforth John Einset Carl Gunnar Fossdal Aksel Granhus Harald Kvaalen Nina Elisabeth Nagy Paivi Liisa Rinne Linda Ripel Sissel Torre Gunnhild Søgaard Christiaan van der SchootSammendrag
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Forfattere
Paivi Liisa Rinne Carl Gunnar Fossdal Sissel Torre Heather Danforth Aksel Granhus Gunnhild Søgaard John Einset Harald Kvaalen Øystein Johnsen Christiaan van der SchootSammendrag
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Forfattere
Svein SolbergSammendrag
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Sammendrag
Det er ikke registrert sammendrag
Forfattere
Lars Sandved Dalen H. Danforth J. Einset Carl Gunnar Fossdal Aksel Granhus Øystein Johnsen Harald Kvaalen Nina Elisabeth Nagy P. Rinne Linda Ripel S. Torre Gunnhild Søgaard C. van der SchootSammendrag
Det er ikke registrert sammendrag
Sammendrag
Ecosystems as objects of natural sciences are often difficult to understand, as an object of traditional management they are sometimes easy to utilize. Computer-based modeling offers new tools to study this apparent paradox.We propose an interactive framework from which the traditional approach based on dynamic system theory can be challenged for living systems: Models derived on the basis of the state concept have not (yet?) allowed predictions that derive novel management competence relevant for the altered boundary conditions of ecosystems. Here a concept of interaction as currently used in information sciences serves as starting point for deriving models more appropriate for ecosystems.An application and test of this concept consists in a search for signatures of interaction in environmental and ecological time series. Confronted with the notorious lack of detailed process understanding, it is plausible to rely on time series analysis techniques. The intricate nature of typical multivariate data sets from ecosystems immediately suggests a preference for nonlinear techniques, and among them temporally local methods, able to detect even subtle changes in the underlying dynamics.We shortly introduce a couple of these methods, which have been demonstrated to be appropriate for time series exceeding minimal length requirements. This is exemplified by recurrence quantification analysis. In addition we present methods to quantify the memory content (Hurst analysis) and complexity of data sets (defined in an informationtheoretic context).Time series analysis of extended environmental and ecological data sets can give detailed structural insights, monitors subtle changes undetectable otherwise, forms the basis for further inferences and provides rigorous model testing on all scales. The success of dynamic system theory when applied to non-living environmental data is strikingly contrasted by the difficulties of the same method when dealing with ecological data We conjecture that this difference reflects the extent to which interaction has been disregarded for ecosystems.