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.
2005
Forfattere
P. Neville Richard Fischer A.L. Axelsson Dan Aamlid Marco Marchetti T.B. Larsson Annemarie Bastrup-BirkSammendrag
The joint network of tree crown condition monitoring under the EU and ICP Forests operates at two levels, a systematic extensive approach (Level I) based on a 16 km x 16 km trans-national grid of sample plots (>6000 plots) and an intensive approach (Level II) on more than 800 plots across continental Europe. Three ongoing projects embrace the different levels of monitoring, the above mentioned Level I and Level II systems, and the National Forest Inventories (NFIs). All of the three projects are based on a stand structure approach that assumes an increased potential for species diversity with increasing complexity of stand structure. An intensive test-phase of forest biodiversity assessment at more than 100 Level II plots, known as ForestBIOTA is underway during 2005. This project aims to test standardized methods of forest biodiversity assessment in the field and examine the relationship between stand structure, forest deadwood, ground vegetation and epiphytic lichens. A forest classification of the plots is also included. A separate approach, known as BioSoil (due to its combination with a detailed chemical inventory of the soils) is a demonstration project which aims to record indicators of forest biodiversity at the extensive Level I plots. Practical measures of stand structure, including records of tree species, lists of vascular plant species, and simple measures of forest deadwood are included for field assessment during 2006. A pan-European forest type classification elaborating on the EUNIS system and including the Natura 2000 habitat types is proposed. These initiatives are linked to a third project, COMON, operating at the level of the National Forest Inventories aiming to test the same core variables at national levels.
Sammendrag
Intensive monitoring plots of the ICP Forests gathered an amount of data about the ground vegetation in forest ecosystems throughout Europe. Each Country, applying different field techniques, conform to common rules of procedure, under the suggestions of a dedicated Expert Panel which implemented a Unified Coded Flora and comparability targets. Data series are foreseen to contribute to: definition of the forest ecosystem state and changes evaluation; assessment of the specific plant diversity at the ecosystems level. The contribution to scientific knowledge and to Global and Pan-European biodiversity initiatives and networks (ICP-IM, MCPFE, CBD, Forest BIOTA, ALTER-net, etc.) are also underlined. In spite of site-related data, first results (more than 670 plots, with large differences in plant diversity) depict the linkages with temperature, precipitation, dominant tree species and actual soil acidity. Nitrogen deposition seems to have some significant influence, which claims to further studies. Plant data series from ICP Forest’s plot, can be used for on-site confirmation of models including biodiversity k-factors and environment relations.
Sammendrag
The spruce bark beetle is the most serious pest of mature spruce trees in Eurasia. At low population densities it breeds in weakened or newly dead trees, but at high densities it becomes a tree killer. The exact factors triggering outbreaks are not fully understood, but climatic variables are important candidates. Populations in SE Norway have been monitored since 1979. Various time series methods are used to explore the role of climate in outbreaks of the spruce bark beetle in space and time, and to estimate the distribution of bivoltism under different scenarios of climate change. Large windfall events appear to be a major synchronizer of beetle outbreaks in areas subjected to regionalized weather systems, and the northern border of bivoltism may be moved towards north as a function of increasing temperature. Preliminary models of the population dynamics emphasize the frequency of large windfall events and phenological changes due to temperature increase. Final aims are to estimate the regional risks of forest damage under different scenarios of climate change, and to describe practices that may reduce the impact for forest managers.
Sammendrag
At least three mechanisms are known to cause synchrony among spatially separated insect populations: 1) dispersal among populations, 2) synchronous stochastic effects, often referred to as the Moran effect, and 3) trophic interactions with other species that are either themselves synchronized or mobile.The present study brings in the role of insect taxa for spatial synchrony. The spatial synchrony observed in several North American and Eurasian epidemic bark beetles was compared with patterns of synchrony in outbreaks of defoliating forest Lepidoptera, revealing a marked difference between these two major insect taxa.The bark beetles exhibited a generally lower degree of spatial synchrony than the Lepidoptera, possibly because bark beetles are synchronized by different weather variables that are acting on a smaller scale than those affecting the Lepidoptera, or because inherent differences in their dynamics leads to more cyclic oscillations and hence more synchronous spatial dynamics in the Lepidoptera. Among the epidemic bark beetles tested, spatial synchrony of outbreaks in the Eurasian spruce bark beetle Ips typographus was significantly higher than for the other species.
Forfattere
Halvor SolheimSammendrag
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Sammendrag
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Sammendrag
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Forfattere
Øystein Johnsen Carl Gunnar Fossdal Nina Elisabeth Nagy Jørgen A.B. Mølmann OG Dæhlen Tore SkrøppaSammendrag
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Sammendrag
In field experiments, clones of Norway spruce [Picea abies (L.) Karst.] showed different degrees of resistance against pathogenic fungi inoculated into the bark that correlate with differences in polyphenolic parenchyma (PP) cells of the bark. Cells of spruce callus cultures, particularly towards the callus surface, resemble PP cells and this study looks at changes in callus cells during infection and the relative resistance of cultures from clones of low (weak) or high (strong) resistance to fungal infection. Callus cultures, initiated from trees with different resistance, were co-inoculated with Ceratocystis polonica (Siem.) C. Moreau and Heterobasidion annosum (Fr.) Bref. Callus cells from strong clones resemble PP cells of bark tissue from strong clones, having more polyphenolic bodies, while callus cells from weak clones are more similar to PP cells from those clones, which have less extensive phenolic bodies. Callus cultures from trees with weak resistance were more quickly overgrown by both species of pathogenic fungi than cultures from trees with strong resistance. Callus cells of infected cultures showed changes similar to activated PP cells of bark, including enhanced accumulation of polyphenolics. Phenolic bodies were more numerous and more extensive (larger and denser) in callus cells of strong versus weak clones under all conditions. Thus, callus cells may perform similar functions in defense as PP cells in the bark. Callus from trees of varying resistance seem to reflect the relative resistance of the trees from which they are derived, and this study indicates that some mechanisms of resistance can be studied using callus from trees of different resistance.
Sammendrag
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