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.
1999
Forfattere
Kari Anne SølvernesSammendrag
The impact of climate change, i.e. elevated atmospheric CO2 and increased temperature, on a mini forest ecosystem was studied for three years in an open-top chamber experiment at s, Norway. Clones of Norway spruce (Picea abies L. Karst.) and one clone of Silver birch (Betula pendula Roth.) were grown in monolithic lysimeters containing undisturbed profiles of boreal forest soil. Seedlings and clones of Norway spruce were also grown in pots with fertilised peat. The atmospheric CO2 concentration was increased with 50 and 100 % of the present CO2 concentration, i.e. to approximately 500 and 700 mol mol-1 CO2. Ambient CO2 (380 mol mol-1 CO2) in chambers and at outside control plots (chamber control) were also included. There were two replicates of each treatment.The soil temperature was increased by 2 - 3 C. Growth and chemical composition of plants, leachates and soil chemistry were measured. Elevated CO2 caused a limited growth increase in Norway spruce and Silver birch. The CO2 effect was largest when the plants received good nutrient supply. The effect of CO2 on height increment was probably depended on growth pattern. When the plant exhibited free growth the stimulation of top shoot elongation was larger than when the plant exhibited predetermined growth. The benefit of elevated CO2 was also probably larger for Silver birch than for Norway spruce. The chemical composition of the plants were almost unaffected by elevated CO2. Increased soil temperature caused an increased mineralisation. Increased amounts of N and Al were released and leached from the soil. The data obtained from the leachates from the 500 mol mol-1 CO2 birch lysimeters during the two last growth seasons were surprisingly and not expected. In these leachates the pH and the concentrations of Al and TOC were increased in both replicates compare to the other treatment with birch. It was hypothesised this could be caused by increased exudations of organic compounds from Silver birch roots induced by elevated CO2
Forfattere
Svein Solberg Steinar DraglandSammendrag
Kepaløk ble høstet til ulik tid og etter ulike metoder. Den ble tørket ved ulik temperatur og fuktighet. Virkningene på groing og utviklingen av glassaktige og læraktige løkskjell ble registrert, og sammenholdt med innholdet av O2 og CO2 i løken.
Forfattere
Marit JørgensenSammendrag
Mixtures of white clover and smooth meadow-grass and pure stands of grass were treated with 0, 40, 80 or 120 kg N ha-1. Yields were compared between all treatments and the proportion of white clover in the mixtures was determined. N2 fixation was estimated by the N-difference method. The experiment was established in 1996 on a sandy loam in Tromsø (690 39"N), northern Norway, under subarctic conditions. The clover/grass mixtures yielded more than pure stands of grass. N-levels significantly affected the dry matter production of the grass, but much less of the mixtures. As N-levels increased from 0 to 120 kg N ha-1 , the yields of the mixture rose from 4.1 t ha-1 to 5.3 t ha-1 while the yields of the grass in pure stand increased from 1.2 t ha-1 to 4.8 t ha-1. Increasing N-levels caused a decrease of the proportion of white clover in the mixtures. With 0 kg N application, white clover made up 63% of the total dry matter yields, whereas at 120 kg Nha-1 the proportion dropped to 19%. Correspondingly, N-application strongly depressed the yields of fixed N2 from 91 kg N ha-1 when no fertilizer N was added, to 30 kg N ha-1 at the highest N-level.
Forfattere
V. Koski Jouni Partanen H. Hänninen Egbert BeukerSammendrag
Det er ikke registrert sammendrag
Forfattere
Nina HeibergSammendrag
The effects of raised beds, black plastic soil mulch and chemical treatment with oxadixyl on raspberry root rot were studied in a field experiment with the cultivar Veten. The results show that plastic mulch and raised beds both individually and when combined reduce the severity of the disease. Best result was obtained with a combination of raised beds, plastic mulch and oxadixyl treatment.
Forfattere
Tor-Gunnar Vagen Yibabe Tilahun Kjell EsserSammendrag
Det er ikke registrert sammendrag
Forfattere
Per Holm NygaardSammendrag
This thesis deals with effects of acidification, fertilisation and addition of Al on boreal vegetation as studied in different field- and laboratory experiments. The results are discussed in relation to the natural vegetation dynamics and critical loads of S and N for forest soils. Field experiments with artificial acid rain caused damage to bryophytes like Pleurozium schreberi and Dicranum polysetum at pH 2.5 and pH 3.0. The presence of Melampyrum pratense was reduced when treated with pH 2.5 and pH 3.0. For the pH 2.5 treatment, a decreased leaf production and decreased internal Mg concentration of Vaccinium myrtillus leaves were recorded. Treatment with pH 2.5 and 3.0 resulted in decreased base saturation in the O and E horizons, in particular Mg2, which may explain the effects on V. myrtillus. Repeated N-fertiliser additions caused vegetation changes, particularly at higher doses (1500 kg N/ha).An increase in cover of the species Deschampsia flexuosa, Molinia caerulea, Agrostis capillaris, Carex canescens, Rubus idaeus, Epilobum angustifolium and Dryopteris assimilis were found 8 years after the last N-application. Chemical analysis of leaves of V. myrtillus demonstrated an increase in N and a decrease in P concentrations on the fertilised plots compared to controls.The concentration of exchangeable Ca2, Mg2and K in the humus layer were reduced in fertilised plots compared to control plots. No differences in pH(H2O) or exchangeable acidity in the humus layer were found between fertilised plots and control plots. Laboratory experiments with Mg-limited Norway spruce seedlings showed that 80 M Al3 and a constant molar Ca/Al ratio of 0.2 decreased the uptake of Ca2 and Mg2, and reduced root length growth. However, no indication of an ameliorating effect of K on Al were seen, therefore these experiments give no support for including K into the critical load criterion. In the critical load calculation it seems that the molar Ca/Al ratio has been emphasised too much, and in particular that the scientific evidence of the critical chemical value (Ca/Al=1) is not well documented. A lot of the processes going on in the forest ecosystem are oversimplified or even left out in the present calculations. Long-term monitoring of forest vegetation at Karlshaugen, under moderate deposition regime of S and N, showed that other processes than deposition of S and N determine the vegetation dynamics, in particular the development of the dominant canopy species and field layer species seems to be much more important because of their influence on light and nutrients. Reduced frequency and persistence were shown for many field layer species and cryptogames during a 60 years period. A comparison of pH in soilwater from O-layer between 1961 and 1991 showed an increase in median pH of 0.1 pH unit for the area
Forfattere
Celine Rebours Chantal Billard Anne Marie Rusig Joel CossonSammendrag
Det er ikke registrert sammendrag
Forfattere
O. Janne Kjønaas Anne Camilla Bergkvist Arne Olav StuanesSammendrag
Det er ikke registrert sammendrag
Forfattere
Ketil Kohmann Hallvard Helland Tormod PedersenSammendrag
Det er ikke registrert sammendrag