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.
2006
Sammendrag
Det er ikke registrert sammendrag
Forfattere
Anders Often J. Wesenberg Harald BratliSammendrag
Det er ikke registrert sammendrag
Forfattere
Ola Ugedal Eva B. Thorstad Tor F. Næsje Laila Saksgård Helge R. Reinertsen Peder Fiske Nils Arne Hvidsten Hans Haavardsholm BlomSammendrag
Det er ikke registrert sammendrag
Sammendrag
Våren 2002 oppdaget flere skogeiere at en del av granplantene som ble plantet ut høsten før hadde toppavdøing. Samtidig registrerte planteskolebestyrere at noen av granplantene som skulle plantes ut hadde visnesymptomer. Ved Skogforsk ble disse plantene undersøkt ved hjelp av tradisjonelle og moderne molekylære teknikker.
Forfattere
Ola Øyen Bernt-Håvard ØyenSammendrag
Det er ikke registrert sammendrag
Forfattere
Kjersti Holt Hanssen M. LiuSammendrag
The use of partial cuttings in spruce (Picea abies L. Karst.) stands is increasing in Norway, especially at sites where special consideration must be taken regarding biodiversity or the recreational value of the forest. However, obtaining sufficient numbers of vital natural regeneration using partial cuttings can be challenging in the Nordic countries, due to harsh climatic conditions and tough competition.We wanted to relate the establishment and growth of natural spruce regeneration to soil conditions and understorey light levels using a thirteen year old field trial with different types of partial cuttings. The field trial was established in a Norway spruce forest on a hillside with varying soil conditions in Oslo, SE Norway. The harvesting treatments included thinning from above, single-tree selection, group felling, shelterwood cuttings and small clear cuts, resulting in a range of cutting intensities and gap sizes.In 2005, spruce seedling establishment as well as growth variables of the tallest seedlings were registered in circular plots of 50 m2 in the different treatments, and soil thickness and moisture class were registered in the same plots. Samples of seedling needles were tested for nitrogen content. Light levels (diffuse, direct and total radiation) below the canopy were measured for each circular plot using hemispherical photography.A covariance analysis with light level as the continuous variable was used to test whether seedling establishment or growth was dependent of soil depth, moisture class or light levels. Diffuse light values corresponded best with seedling growth. The levels of diffuse light in the partial cuttings varied from 19 to 30 % of above canopy values, with the shelterwoods and the group fellings having the highest levels. Still, the clear cuts had light levels more than twice as high as the shelterwoods.The number of spruce regeneration varied substantially between plots with the same harvesting treatment. Seedling numbers were dependent on soil conditions, and were highest on sites with good moisture conditions and soil thickness 20 cm. The covariance analysis did not give a significant effect of light values on spruce seedling number, but there was a tendency to better regeneration at medium light levels.However, the growth of the seedlings was strongly dependent on light levels, with taller leader length and total growth as well as a higher number of annual shoots under good light conditions.Soil depth was insignificant for seedling growth, but moisture class affected annual height growth. Nitrogen concentration in seedling needles was positively correlated with light conditions and negatively with stand density in the vicinity of the seedling, which indicates that the positive effect of large gaps on seedling growth may be caused by decreased competition for nutrients as well as increased radiation levels. Soil depth did not influence the nitrogen concentration.
Forfattere
Mauro Bernabei Peder GjerdrumSammendrag
NOAA Paleoclimatology betjener et World Data Center for Paleoclimatology, herunder en database for årringobservasjoner. Vi har ønsket å gjøre våre observasjoner av barlind fra det italienske Alpe-området allment tilgjengelige gjennom registrering i denne databasen: http://www.ncdc.noaa.gov/paleo/paleo.html Velg Tree-Ring og søk blant tilgjengelige data.
Sammendrag
Fine root production, respiration, longevity and mortality are the major processes in carbon dynamics of the forest soils. The objective of the present work was to determine fine root biomass, respiration and root longevity. The study was carried out at a ten year-old stand of planted Norway spruce (Picea abies) (a clearcut, dominated by natural regrowth of Scots pine and birch) and three stands of Norway spruce, approximately 30, 60 and 120 years old, during 2001 and 2002. The stands were located at Nordmoen, a plain of sandy deposits in southeast Norway.Root biomass of both trees and understorey vegetation (0-1, 1-2 and 2-5 mm in diameter) in the humus layer and mineral soil horizons (to depth of 60 cm) was sampled by soil coring. Root respiration was performed in situ, by measuring the CO2 of excavated fine roots by using the CIRAS-I portable gas analyser. For the root turnover study, altogether 60 minirhizotrones were installed and images were processed. Root biomass and necromass (g m-2), specific root length (SRL, m g -1), root length density (RLD, cm cm-3), number of root-tips and mean longevity (y) were estimated.Root biomass was 2-3 times higher in the mineral soil than in the humus horizon. Compared with other stands, root biomass, SRL, RLD and the number of root tips were highest in the 30-year-old stand. At the 10 and 120 year-old stands understorey vegetation roots counted for 70 and 40% of total root biomass, respectively. The amount of necromass at 60 year-old stand was about twice as high (45%) compared to other stands.Root respiration (g C/min./g roots) was significantly lowest at 10-year-old stand. Root respiration among 30, 60 and 120 year-old stands was not significantly different, but it was highest in the 60-year-old stand. The respiration varied seasonally, with high peaks during the summer and lower values during the spring and autumn. Fine root longevity of tree and understorey roots at the 10-year-old stand were 1.2 and 1.4 years, respectively.It is concluded that stand age may influence the dynamics of the fine roots. The complexity of influences will be discussed.
Sammendrag
Kortdagsbehandling i planteskolene sikrer god innvintring og er derfor anbefalt før tidlig høstplanting av gran. Forsøk viser at kortdagsbehandling utført på riktig tidspunkt også forbedrer plantenes frosttoleranse i vekstfasen etter utplanting.
Forfattere
Peder GjerdrumSammendrag
Skrivet omtaler innflytelse på fiberforløpet av vridd vekst, kvister, buktende toppskudd og urundt stammetverrsnitt.