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.
2008
Sammendrag
Det er ikke registrert sammendrag
Sammendrag
Detailed knowledge of temperature effects on the timing of dormancy development and bud burst will help evaluate the impacts of climate change on forest trees. We tested the effects of temperature applied during short-day treatment, duration of short-day treatment, duration of chilling and light regime applied during forcing on the timing of bud burst in 1- and 2-year-old seedlings of nine provenances of Norway spruce (Picea abies (L.) Karst.). High temperature during dormancy induction, little or no chilling and low temperature during forcing all delayed dormancy release but did not prevent bud burst or growth onset provided the seedlings were forced under long-day conditions. Without chilling, bud burst occurred in about 20% of seedlings kept in short days at 12 C, indicating that young Norway spruce seedlings do not exhibit true bud dormancy. Chilling hastened bud burst and removed the long photoperiod requirement, but the effect of high temperature applied during dormancy induction was observed even after prolonged chilling. Extension of the short-day treatment from 4 to 8 or 12 weeks hastened bud burst. The effect of treatments applied during dormancy development was larger than that of provenance; in some cases no provenance effect was detected, but in 1-year-old seedlings, time to bud burst decreased linearly with increasing latitude of origin. Differences among provenances were complicated by different responses of some origins to light conditions under long-day forcing. In conclusion, timing of bud burst in Norway spruce seedlings is significantly affected by temperature during bud set, and these effects are modified by chilling and environmental conditions during forcing.
2007
Forfattere
O. Janne KjønaasSammendrag
Det er ikke registrert sammendrag
Forfattere
O. Janne KjønaasSammendrag
Det er ikke registrert sammendrag
Sammendrag
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Sammendrag
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Sammendrag
In winter 2000-2001, there was a serious outbreak of Gremmeniella abietina Morelet in southeastern Norway. During the outbreak, we noted that injured Scots pine trees (Pinus sylvestris L.) developed secondary buds in response to the fungus attack, and we decided to study the relationship between injury, appearance of secondary buds and recovery of the trees thereafter. For this purpose, 143 trees from 10 to 50 years of age were chosen and grouped into crown density classes. Injury was assessed in detail, and buds were counted before bud burst in the spring of 2002. In addition, a subset of 15 trees was followed through the summer of 2002 to assess recovery. All injured trees developed secondary buds, with a clear overweight of dormant winter buds in proportion to interfoliar buds. Healthy control trees did not develop secondary buds at all. The secondary buds appeared predominantly on the injured parts of the tree; interfoliar buds in particular developed just beneath the damaged tissue. Most of the secondary buds died during the winter of 2001-2002, mainly because the fungus continued to spread after the first outbreak. Many of the remaining buds developed shoots with abnormal growth during the summer. Secondary buds may help trees to recover from Gremmeniella attacks, but this strategy may fail when the fungus continues to grow and injure the newly formed buds and shoots.
2006
Sammendrag
Det er ikke registrert sammendrag
Sammendrag
Det er ikke registrert sammendrag
Forfattere
Linda H. Pardo P. H. Templer C. L. Goodale S. Duke P. M. Groffman M. B. Adams P. Boeckx J. Boggs J. Campbell B. Coleman J. Compton Bridget A Emmett Per Gundersen O. Janne Kjønaas G. Lovett M. Mack Alison Magill M. Mbila Myron J. Mitchell G. McGee Steven McNulty Knute Nadelhoffer S. Ollinger D. Ross H. Rueth Lindsey Rustad P. Schaberg Sheryl Schiff Patrick Schleppi J Spoelstra Wim WesselSammendrag
N saturation induced by atmospheric N deposition can have serious consequences for forest health in many regions. In order to evaluate whether foliar d15N may be a robust, regional-scale measure of the onset of N saturation in forest ecosystems, we assembled a large dataset on atmospheric N deposition, foliar and root d15N and N concentration, soil C:N, mineralization and nitrification. The dataset included sites in northeastern North America, Colorado, Alaska, southern Chile and Europe. Local drivers of N cycling (net nitrification and mineralization, and forest floor and soil C:N) were more closely coupled with foliar d15N than the regional driver of N deposition. Foliar d15N increased non-linearly with nitrification:mineralization ratio and decreased with forest floor C:N. Foliar d15N was more strongly related to nitrification rates than was foliar N concentration, but concentration was more strongly correlated with N deposition. Root d15N was more tightly coupled to forest floor properties than was foliar d15N. We observed a pattern of decreasing foliar d15N values across the following species: American beech>yellow birch>sugar maple. Other factors that affected foliar d15N included species composition and climate. Relationships between foliar d15N and soil variables were stronger when analyzed on a species by species basis than when many species were lumped. European sites showed distinct patterns of lower foliar d15N, due to the importance of ammonium deposition in this region. Our results suggest that examining d15N values of foliage may improve understanding of how forests respond to the cascading effects of N deposition.