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.
1991
Forfattere
Oddvar SkreSammendrag
Seedlings of four populations from the two mentioned species were grown for 6 weeks in varying temperature, light and daylength. In accordance with earlier studies there was a strong latitudinal effect on the critical daylengths for growth. There was also a weaker, but significant effect due to altitude. Large differences were also found in growth pattern and compensation mechanisms. Fast-growing lowland populations reacted to low light levels and high temperatures by increasing their shoot/root ratios and the temperature optimum for shoot elongation. In mountain birch from Kevo, northern Finland, plants reacted to increasing temperatures by increasing their net assimilation rates. The shoot/root ratios and leaf area ratios were highest at the early stages of growth while maximum net assimilation occurred later. This illustrates the high priority in birch for leaf growth. In all populations except the northern population the plants grew better in alternating day and night temperatures than at the corresponding constant temperature.
Forfattere
Per Holm Nygaard Gunnar AbrahamsenSammendrag
A study on the effects of eight years application of artificial acid rain on the vegetation and soil in an old Scots pine forest is described. Artificial rain of pH 2.5 and 3.0 caused severe damage to mosses, especially Pleurozium schreberi and Dicranum polysetum. The presence of Melampyrum pratense decreased drastically in plots treated with rain of pH 2.5 and 3.0. In Vaccinium myrtillus reduced leaf production was found in plots treated with rain of pH 2.5. A considerable decrease in base saturation had taken place in plots treated with pH 2.5 and pH 3.0 rain. Exchangeable calcium and magnesium in particular had been reduced, and the content of mangnesium in tissue of Vaccinium myrtillus appeared also to be reduced in plots treated with water of pH 2.5. The study demonstrates the need for better methods in evaluating vegetation responses in field studies. The use of visual cover recording should be supplemented by frequency analysis and harvesting methods to get better estimates of changes in vegetation structure.
Forfattere
Oddvar SkreSammendrag
Support is given for the dark respiration as a limiting factor for growth at low temperatures. The existence of a so-called alternative respiration that is not linked to the growth process, supports this hypothesis, because of its possible function as a stabilizing factor (overflow function). Physiological mechanisms influencing plant survival in a cold environment and tree-line forming processes are discussed.
Forfattere
Gunnar Ogner Magne Opem Gabriele Remedios Gro Sjøtveit Britt SørlieSammendrag
Det er ikke registrert sammendrag
Forfattere
Carl Gunnar Fossdal O. Nilssen B. Myhre B.H. LindqvistSammendrag
Det er ikke registrert sammendrag
Forfattere
O. Marvik S. Rishovd Praveen Sharma Carl Gunnar Fossdal B.H. LindqvistSammendrag
Det er ikke registrert sammendrag
Forfattere
Torild Wickstrøm W. Lund R. ByeSammendrag
Selenium is determined in copper and nickel materials without any interferences. Hydrochloric acid plus hydrogen peroxide are used to dissolve the samples. The solution is then made alkaline with sodium hydroxide in order to eliminate the interference from copper and nickel by precipitation of the corresponding hydroxides. Sodium tetrahydroborate is added to the alkaline solution in order to reduce selenium(IV) to the selenide ion, and the solution is then filtered. The volatile selenium hydride is generated by acidification of the alkaline solution in a continuous flow system. The method was used successfully for the determination of selenium in three standard reference materials (SRMs) from the National Institute of Standards and Technology: SRM 398 Unalloyed Copper V, SRM 671 Nickel Oxide 1 and SRM 875 Cupro-Nickel, 10 (CDA 706) (doped). The detection limit of the method was approximately 1-mu-g g-1.
Forfattere
Svein SolbergSammendrag
Skogens vitalitet er vurdert ut fra kronetetthet og kronefarge på 772 overvåkingsflater i 1991, totalt ca 47000 trær. Vurderingene startet i 1988, og endringene fra år til år er beregnet. Det har jevnt over vært en svak nedgang i kronetetthet siden 1988. Siden i fjor har det vært små endringer. Laveste kronetetthet finner vi blant ekstremflater av gran på Østlandet og i Trøndelag, og på furuflatene i Finnmark. Siden i fjor har det vært en tydelig økning av gulfarging på granflatene i den sørlige del av Sørøst-Norge, og delvis i Nord-Norge. Dette er sannsynligvis reelle endringer, som ikke er en del av en jevn, negativ trend siden 1988, men er spesielle for i år. Skogens vitalitet vurdert ut fra de registrerte kriteriene synes å ha blitt noe redusert siden 1988. I enkelte fylker har det siden 1988 vært store årlige svingninger både i kronetetthet og farge. Dette kan være reelle endringer for gran, mens resultatene for furu er mer usikre. Store, årlige svingninger kan forøvrig tyde på at skogen i visse områder er mer labil enn ellers i landet.
Forfattere
O. Nilssen Carl Gunnar Fossdal K. Eian B.H. LindqvistSammendrag
Det er ikke registrert sammendrag
Forfattere
Severin WoxholttSammendrag
Det er ikke registrert sammendrag