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.
2009
Sammendrag
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Sammendrag
Minirhizotrons, transparent acrylic tubes inserted in the soil, are well suited for long term, non destructive, in situ observations of fine roots. In minirhizotrons, the fine roots are regularly photographed and the root images are visually evaluated according to their status as living, dead or disappeared. This evaluation gives the background for further statistical treatment to estimate the fine root longevity. It is inherent in the minirhizotron technique that a large group of roots will be described as “disappeared” due to grazing, overgrowing by other roots, unclear images or other reasons. Because the fraction of disappeared roots is substantial in some cases, this has consequences for the interpretation of the longevity results. We processed three years of minirhizotron images from Norway spruce stands in southeast Norway (30 yr old) and northern Finland (60 yr old). Of all processed fine roots 32 and 23% was evaluated as disappeared in Norway and Finland, respectively. When roots labelled as disappeared were pooled together with dead ones, the fine root longevity estimates, using the Kaplan Meier method, decreased almost by a factor of two (401 and 433 days), as opposed to labeling them as censored observations (770 and 750 days for Norway and Finland, respectively). Here we demonstrate how the early decision making on the fine root status bears consequences on the resulting longevity estimates. The implications will be discussed
Sammendrag
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Forfattere
Ari Hietala Nina Elisabeth Nagy Arne Steffenrem Harald Kvaalen Carl Gunnar Fossdal Halvor SolheimSammendrag
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Sammendrag
In trees adapted to cold climates, conditions during autumn and winter may influence the subsequent timing of bud burst and hence tree survival during early spring frosts. We tested the effects of two temperatures during, dormancy induction Mid mild spells (MS) during chilling, on the timing of bud burst in three Picea abies (L.) Karst. provenances (58-66 degrees N). One-year-old seedlings were induced to become dormant at temperatures of 12 or 21 degrees C applied during 9 weeks of short days (12-h photoperiod). The seedlings were then moved to cold storage and given either continuous chilling at 0.7 degrees C (control), or chilling interrupted by one 14-day MS it either 8 or 12 degrees C. Interruptions with MS were staggered throughout the 175-day chilling period, resulting in 10 MS differing in date of onset. Subsets of seedlings were moved to forcing conditions (12-h photoperiod, 12 degrees C) throughout the chilling period, to assess dormancy status different timings of the MS treatment. Finally, after 175 days of chilling, timing of bud burst was assessed in a 24-h photoperiod at 12 degrees C (control and MS-treated seedlings). The MS treatment did not significantly affect days to bud burst when given early (after 7-35 chilling days). When MS was given after 49 chilling days or later, the seedlings burst bud earlier than the controls, and the difference increased with increasing length of the chilling period given before the MS. The 12 degrees C MS treatment was more effective than the 8 degrees C MS treatment, and the difference remained constant after the seedlings had received 66 or more chilling days before the MS treatment was applied. In all provenances, a constant temperature of 21 degrees C during dormancy induction resulted in more dormant seedlings (delayed bud burst) than a constant temperature of 12 degrees C, but this did not delay the response to the MS treatment.
Forfattere
Øystein Johnsen Harald Kvaalen Igor A. Yakovlev O.G. Dæhlen Carl Gunnar Fossdal Tore SkrøppaSammendrag
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2008
Sammendrag
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Sammendrag
Progenies from a natural stand of Picea abies planted on a forest site with heterogeneous growth conditions were characterized for genetic and environmental control of internodal and whorl branch formation and lammas growth. The progenies studied were 27 years old from seed and planted in a randomized complete block experiment. Internodes and whorls studied were located in the top section of the trees. Significant genetic variation (p<0.01) was found for a number of internodal and whorl branches. Block means for the length of internodes, a strong indicator for the site index in respective blocks, were correlated strongly with branch dimensions (r >= 0.90), intermediately with the frequency of lammas growth (r = 0.81) and number of branches in whorls (r = 0.68), and only weakly with the number of internodal branches per length unit of internode (r = 0.25). A strong environmental effect on branch dimensions was supported by the relative size of variance components. The results show that the environmental effect expressed by site index dominates the control of branch dimensions, while the number of branches is under stronger genetic control in P. abies.
Sammendrag
This paper reports the results from a study of modulus of elasticity (MOE) and modulus of rupture (MOR) of 42 small clear specimens prepared from 300 year old roundwood floor girders containing high levels of NaCl at Bryggen in Bergen, Norway. NaCl concentration was 6.5 % of the dry matter of the wood. MOE and MOR were 25 % lower than the values obtained from a reference material with equivalent annual ring width and density. The considerable reduction of MOE and MOR should be taken into consideration in conservation of load-bearing wooden structures that have been exposed to NaCl.
Sammendrag
Denne rapporten omtalar ein forsøksserie med dei nordamerikanske treslaga blågran (Picea pungens Engelm.), engelmannsgran (Picea engelmannii Parry), fjelledelgran (Abies lasiocarpa (Hook.) Nutt.) og korkedelgran (Abies lasiocarpa var. arizonica (Merriam) Lemmon), og dei austasiatiske treslaga ajangran (Picea jezoensis (Sieb. et. Zucc.) Carr.) og hondogran (Picea jezoensis var. hondoensis (Mayr) Rehd.). Formålet med forsøket har vore å finne ut om proveniensar av desse treslaga, dei fleste henta frå høgt over havet i dei naturlege utbreiingsområda, kan vera eigna til juletredyrking i låglandet og dalstrok i Sør-Noreg. Forsøksmaterialet omfattar ein proveniens av kvar av ajan- og hondogran, og frå to til seks proveniensar av kvart av dei andre treslaga. Eitt forsøksfelt vart lagt ut i kvar av kommunane Bergen, Hjartdal, Modum, Rennebu, Ringebu og Trysil .....