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.
1988
Authors
Bjørn Langerud Martin SandvikAbstract
The paper reports on changes in physical properties of growth media/substrates caused by frequent drying before re-irrigation. The peat/perlite mixtures were systematically dried to defined levels for 104 days in single pots, each including one Norway spruce seedling. Irrigation regimes were defined in relation to the volume of liquid in the substrates at container capacity when the experiment started (initially). Single pots were re-irrigated with nutrient solution as 10, 30, 50 and 70 % of that volume of liquid was consumed. Growth substrate volume and bulk density, and the fraction of perlite mixed with the peat were measured initially and at the termination of the experiment (finally). The volume fraction of gas filled pores was obtained gravimetrically at least once a day to describe changes in the liquid status of the growth substrates. The volume of substrate stayed constant in all irrigation regimes during the experimental period. The bulk density was independent of the fraction of perlite, but it was lower finally than initially for substrates subjected to the most frequent irrigation. The initial volume fraction of gas filled pores was negatively correlated with the initial bulk density, and the linear regressions depended on the fraction of perlite. The volume fraction of gas filled pores at container capacity (fgcc) increased during the experiment from .33 to .50 ml ml-1 for substrates subjected to the most dry conditions, and from .33 to .41 ml ml-1 in regimes allowing 30 and 50 % liquid losses. For substrates subjected to the least dry conditions, fgcc decreased from .30 to .26 ml ml-1. Initial and final fgcc was positively correlated. The linear regressions were different for the different irrigation regimes as indicated by their average changes described above.
– Variations in ground water level at the field station Nordmoen, Romerike
Kristian Bjor, Magne Huse
Authors
Kristian Bjor Magne HuseAbstract
No abstract has been registered
Authors
Finn Roll-HansenAbstract
No abstract has been registered
Authors
Gunnar Ogner Kristian BjorAbstract
No abstract has been registered
Authors
Oddvar SkreAbstract
No abstract has been registered
Authors
Oddvar SkreAbstract
No abstract has been registered
Authors
Tonje ØklandAbstract
The vegetation in a beech forest, Fritzøehusparken, is analysed using one hundred sample plots, each 25 m2, distributed by a restricted random procedure. Percentage cover and frequency in subplots are used for quantification of species amounts, and their relative performance are evaluated. Advantages of choosing frequency in subplots are discussed.Thirteen environmental variables are measured from each of the sample plots. The vegetation is divided into four topographical/ecological types. This classification served as a reference in the further treatment. Ecological gradients corresponding to the most important vegetational gradients in the beech forest are identified by means of DCA ordination followed by statistical interpretation. Two main complex gradients were recognized; (1) the gradient in nutrient conditions, and (2), the gradient inlitter-wind conditions. The advantages of using DCA and statistical interpretation with integration of ecological measurements are emphasized.
Authors
Simen GjølsjøAbstract
No abstract has been registered
Abstract
No abstract has been registered
Authors
Tore SkrøppaAbstract
No abstract has been registered