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.
2013
Sammendrag
Artikkelen gjev eit oversyn over kunnskap om soppsjukdomen bitterrote på søtkirsebær.
Sammendrag
Det er ikke registrert sammendrag
Sammendrag
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Sammendrag
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Forfattere
Mark J. Ducey Rasmus Astrup Stefan Seifert Hans C. Pretzsch Bruce C. Larson K. David CoatesSammendrag
Terrestrial lidar (TLS) is an emerging technology for deriving forest attributes, including conventional inventory and canopy characterizations. However, little is known about the influence of scanner specifications on derived forest parameters. We compared two TLS systems at two sites in British Columbia. Common scanning benchmarks and identical algorithms were used to obtain estimates of tree diameter, position, and canopy characteristics. Visualization of range images and point clouds showed clear differences, even though both scanners were relatively high-resolution instruments. These translated into quantifiable differences in impulse penetration, characterization of stems and crowns far from the scan location, and gap fraction. Differences between scanners in estimates of effective plant area index were greater than differences between sites. Both scanners provided a detailed digital model of forest structure, and gross structural characterizations (including crown dimensions and position) were relatively robust; but comparison of canopy density metrics may require consideration of scanner attributes.
Forfattere
Mallikarjuna Rao Kovi Mats Höglind Hans Martin Hanslin Åshild Ergon Torben Asp Odd Arne RognliSammendrag
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Sammendrag
Six trap models were compared with respect to their ability to capture European spruce bark beetles and technical details in handling and use. All trap models proved to be efficient and gave high captures of beetles during operation for one summer season (2013). Ranking the trap models in descending order of total capture of beetles gave this list: Lindgren trap, Theysohn, prototype-P, Ecotrap, BEKA, and prototype-K. However, there was much variation in trapping results between localities for all trap models, and the estimated means did in most cases not differ significantly between models. The estimated mean capture of the Lindgren trap was significantly higher than for prototype-K and BEKA, but their confidence intervals were wide and they were close to being insignificantly different. The retail price of the traps vary from about 10 € (Ecotrap) to 50-55 € (Lindgren), while prices are not available for the two prototypes, which are not in regular production. Advantages and disadvantages concerning weight, size, robustness, draining of rain water, ease of handling and mounting are commented on in the discussion, and technical details of the traps are presented in a separate appendix (6).
Sammendrag
1. Whether plant competition grows stronger or weaker across a soil fertility gradient is an area of great debate in plant ecology. We examined the effects of competition and soil fertility and their interaction on growth rates of the four dominant tree species in the sub-boreal spruce forest of British Columbia. 2. We tested separate soil nutrient and moisture indices and found much stronger support for models that included the nutrient index as a measure of soil fertility. 3. Competition, soil fertility and their interaction affected radial growth rates for all species. 4. Each species supported a different alternate hypothesis for how competitive interactions changed with soil fertility and whether competition intensity was stronger or weaker overall as soil fertility increased depended on the context, specifically, species, neighbourhood composition and type of competition (shading vs. crowding). 5. The four species varied slightly in their growth response to soil fertility. 6. Individual species had some large variations in the shapes of their negative relationships between shading, crowding and tree growth, with one species experiencing no net negative effects of crowding at low soil fertility. 7. Goodness-of-fit was not substantially increased by models including competition–soil fertility interactions for any species. Tree size, soil fertility, shading and crowding predicted most of the variation in tree growth rates in the sub-boreal spruce forest. 8. Synthesis. The intensity of competition among trees across a fertility gradient was species- and context-specific and more complicated than that predicted by any one of the dominant existing theories in plant ecology.
Forfattere
Rainer Matyssek Thomas Knoke Nicholas Clarke Pavel Cudlin Teis Nørgaard Mikkelsen Juha-Pekka Tuovinen Gerhard Wieser Elena PaolettiSammendrag
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Forfattere
Joachim Paul Spindelbøck Zöe Cook Matthew I. Daws Einar Heegaard Inger Elisabeth Måren Vigdis VandvikSammendrag
Background and Aims: Across their range, widely distributed species are exposed to a variety of climatic and other environmental conditions, and accordingly may display variation in life history strategies. For seed germination in cold climates, two contrasting responses to variation in winter temperature have been documented: first, an increased ability to germinate at low temperatures (cold tolerance) as winter temperatures decrease, and secondly a reduced ability to germinate at low temperatures (cold avoidance) that concentrates germination towards the warmer parts of the season. Methods: Germination responses were tested for Calluna vulgaris, the dominant species of European heathlands, from ten populations collected along broad-scale bioclimatic gradients (latitude, altitude) in Norway, covering a substantial fraction of the species' climatic range. Incubation treatments varied from 10 to 25 °C, and germination performance across populations was analysed in relation to temperature conditions at the seed collection locations. Key Results: Seeds from all populations germinated rapidly and to high final percentages under the warmer incubation temperatures. Under low incubation temperatures, cold-climate populations had significantly lower germination rates and percentages than warm-climate populations. While germination rates and percentages also increased with seed mass, seed mass did not vary along the climatic gradients, and therefore did not explain the variation in germination responses. Conclusions: Variation in germination responses among Calluna populations was consistent with increased temperature requirements for germination towards colder climates, indicating a cold-avoidance germination strategy conditional on the temperature at the seeds' origin. Along a gradient of increasing temperatures this suggests a shift in selection pressures on germination from climatic adversity (i.e. low temperatures and potential frost risk in early or late season) to competitive performance and better exploitation of the entire growing season.