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.
2010
Sammendrag
Scots pine (Pinus sylvestris) sapwood is per definition (EN-350-2) easy to treat. Combination with its good availability on the European markets, it is a construction and building material in demand. However, partially large differences in penetration are reported from industry and research. To keep a reliable product quality, impregnation processes aligned to the material most difficult to treat. Hence, it is crucial to know about the factors inhibiting the fluid flow into the material. Scots pine samples from a wide geographic distribution, 25 different sites in 6 different countries, have been collected and impregnated with an aqueous monomer furfuryl alcohol solution. From each of the respective sites logs of 1.3 meter in length were collected from nine trees belonging to three different breast height diameter classes. Three trees from each dominance class were chosen randomly. The log was drawn from the felled stem in a height of 1.2 meters with exact marked north/south exposition. Sapwood slabs orientated in the heaven directions, underwent a drying procedure at 40°C for 48 h and small clear samples of 20 x 20 x 50 mm were prepared. A large variation of the ratio of filling was found for the material tested. Diameter as well as sample origin seem to influence the materials permeability.
2009
Sammendrag
Ett skördaraggregat med sågsvärd och matarhjul gav högst prestation i en avverkning av skogsbränsle. Det hade bättre flerträdshantering än övriga aggregat i studien och tack vare matarhjulen lättare att få ner trädknippena på marken.
Sammendrag
I denne rapporten redegjøres for et mindre studie av produktiviteten ved uttransport av ukomprimert vegkantvirke som er tenkt benyttet som biobrensel. Tre forskjellige maskiner har blitt studert; tømmerbil, lassbærer og landbrukstraktor med kran og tømmerhenger. Lassbæreren og landbrukstraktoren ble benyttet til å samle virke langs vegen og kjøre det til lunneplass. Tømmerbilen ble benyttet til videre transport til terminal. Bestandene var lauvtredominerte vegkanter som ble manuelt ryddet noen dager før utkjøring. Den gjennomsnittelige størrelsen på trærne i hvert lass varierte fra 10 til 40 liter per tre. Lessetiden var det enkeltmomentet med størst variasjon og med størst innflytelse på kostnadene i hele kjeden. Tidsforbruket for lessing var sterkt avhengig av hivstørrelsen, noe som stemmer godt overens med hva andre studier har vist. I dette studiet var den totale opplessingstiden i de fleste tilfeller mellom 5 og 10 minutter per fastkubikkmeter (fmP 3 P), og i ett tilfelle oppe i 18 minutter per fmP 3 P. Dette gir en arbeidskostnad i intervallet 70 - 210 kr per fmP 3 P for opplessingen. Det store spennet skyldtes i hovedsak stor variasjon i hvor lett det var å samle sammen virket på bakken i forbindelse med opplessingen. Den store variasjonen i dette arbeidsmomentet tyder også på at det er mye å hente på å endre arbeidsmetodene allerede i fellingsmomentet, slik at virket i større grad blir konsentrert og ”lettgripelig”. Landbrukstraktoren kom godt ut sammenlignet med lassbæreren i dette studiet, noe som hovedsakelig skyldtes en lavere timekostnad. Produktiviteten var den samme for begge maskiner. På lengre transportavstander vil landbrukstraktoren være mer effektiv enn lassbæreren på grunn av noe høyere transporthastighet på veg.
Sammendrag
Det er ikke registrert sammendrag
Sammendrag
Det er ikke registrert sammendrag
Forfattere
Igor A. Yakovlev Harald Kvaalen Carl Gunnar Fossdal Øystein JohnsenSammendrag
MicroRNAs (miRNAs) are endogenous small RNAs that can have large-scale regulatory effect and could participate in epigenetic regulation of gene expression in plants. We show for the first time that temperature during zygotic embryogenesis and seed maturation in Norway spruce regulates an “epigenetic memory” in the progeny, regenerated through somatic embryogenesis. The warmer the in vitro temperature applied, the later the regenerated plants formed terminal buds in the common environment the second growth season. The differences were very large, and similar in size to a provenance separation of 4 – 6 degrees of latitude (Kvaalen and Johnsen, 2008). To study a molecular mechanisms of a memory from embryo development we have prepared two concatemerized small RNA libraries representing small RNAs predominantly expressed in plants growing from seeds obtained after embryogenesis in cold environment (CEL) and warm environment (WEL) after short day (SD) treatment (going to bud set). In total we obtained 201 different small RNAs, with dominated length of 21-nt, 123 from WEL and 93 from CEL. Using multiple methods, including BLAST, sequence alignment and sequence folding we found 27 novel candidate miRNAs and only 3 earlier described. Additionally 103 small RNAs have exact matches in spruce EST database, which could be their putative targets and 67 small RNAs have no matches. We used quantitative RT–PCR to study the expression patterns of 31 chosen candidate miRNAs and monitor the occurrence stage-dependent miRNA-mediated cleavage for 4 regions of putative mRNA targets. All miRNA show difference in transcript levels after SD treatment and 12 miRNAs show constitutively differential expression in progeny from CE and WE. Kvaalen H, Johnsen O (2008) Timing of bud set in Picea abies is regulated by a memory of temperature during zygotic and somatic embryogenesis. New Phytologist 177: 49-59
Sammendrag
Wood is a traditional building material but in general it underlies restrictions in outdoor applications due to its respective durability against microbiological decay. To face this problem, different impregnation systems are applied to enhance the materials\" servicelife. Scots pine (Pinus sylvestris) is the most widely distributed pine in Eurasia and hence easily available. Despite of the previously defined good treatability of Scots pine sapwood, large differences in treatment performance are reported from industry. As process parameters are always adjusted to the material most difficult to treat, permeability variations in wood material are an economical problem. Therefore, it is important to understand the material in order to make a more reasonable material selection possible.....
2008
Sammendrag
Det er ikke registrert sammendrag
Sammendrag
Bruken av bioenergi kommer til å øke betraktelig i årene som kommer. Politisk ligger det målsettinger om en dobling av bruken i løpet av 12 år, og utbyggingstakten i fjernvarmesektoren er nær femdoblet siste fem år. Mange aktører står derfor på første trinn i læringskurven og skal vurdere ulike typer brensel, samt utforme en effektiv forsyningskjede for dette brenselet. Å ha en viss kontroll med kvalitet og kvantitet på brenselet er en forutsetning for å klare dette. En kubikk flis kan være så mangt. Grove målemetoder kan gi svært grove estimat på energimengden man har for hånden. Ulike definisjoner på brennverdi er av og til opphav til forvirring om energimengden i brenselet og virkningsgraden i ulike forbrenningsanlegg.....
Forfattere
Øystein Johnsen Igor A. Yakovlev Daniel Kwaku A. Asante Anne Eskild Nilsen Harald Kvaalen Carl Gunnar FossdalSammendrag
In forest trees, environmental conditions during the reproduction can greatly influence progeny performance. We here suggest that temperature during zygotic embryogenesis and seed maturation regulates an “epigenetic memory” in the progeny, involving differential expression of genes that may regulate bud phenology, cold acclimation and embryogenesis in Norway spruce. Conditions colder than normal advance the timing whilst temperatures above normal delay the onset of these processes. The altered performance lasts for many years. The seedlings actually remember the temperatures and photoperiod prevailing during zygotic embryogenesis and seed maturation. We show for the first time that regenerated plants, cloned through somatic embryogenesis, express a memory of the temperatures applied during embryo development whilst growing in a common greenhouse environment. The warmer the in vitro temperature applied, the later the regenerated plants formed terminal buds in the common environment the second growth season. The differences were very large, and similar in size to a provenance separation of 4 – 6 degrees of latitude. To study a molecular mechanisms of a memory from embryo development identical crosses were performed, seed were produced in different temperature regimes (cold and warm embryonic history) and seedling were grown under long day (LD = continuous light) and short day (SD = 12 h night) conditions. We have prepared two subtracted cDNA libraries, forward and revers, representing genes predominantly expressed in plants growing from seeds obtained after embryogenesis in cold environment (CE) and warm environment (WE) after short day treatment (going to bud set). Annotation reveals considerable differences in studied transcriptomes. More than 50% of contigs were unknown. So obtained subtracted libraries is a good source of candidate genes. We used quantitative RT–PCR to study the expression patterns of 34 chosen candidate genes. Just two putative genes among them with no matching in the Database and one reverse transcriptase show constitutively differential expression in progeny from CE and WE