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.
2011
Forfattere
Vidar Selås Geir Sonerud Erik Framstad John Atle Kålås Sverre Kobro Helge B. Pedersen Tor Kristian Spidsø Øystein WiigSammendrag
Grouse and vole numbers may peak after peaks in the seed crop of bilberry (Vaccinium myrtillus) because of reduced levels of feeding deterrents in bilberry plants. We predicted that grouse reproduction depends also on summer (June-September) temperatures in the 2 previous years, because bilberry plants will be less exhausted after a high seed crop in or after warm summers, and thus rebuild their chemical defence more quickly. After berry peak years, population indices of capercaillie (Tetrao urogallus) and bank vole (Myodes glareolus) in southern Norway were negatively related to summer temperatures in the previous year or previous 2 years. Willow grouse (Lagopus lagopus) chick production in five areas in Norway was negatively related to summer temperatures in the 2 previous years when controlling for vole density. A similar pattern was found for the bilberry-feeding moth (Eulithis populata), an important prey for grouse chicks. In eastern Norway, autumn densities of capercaillie and black grouse (Tetrao tetrix) were more likely to peak in vole peak years at high altitudes, where summer temperatures are low. We conclude that high summer temperatures may limit grouse reproduction through the effect on bilberry plants and that a warm climate thus adversely affects population levels of grouse.
Forfattere
Kyrre Linné Kausrud Jean-Claude Grégoire Olav Skarpaas Nadir Erbilgin Marius Gilbert Bjørn Økland Nils Christian StensethSammendrag
Bark beetles (Coleoptera: Curculionidae, Scolytinae) feed and breed in dead or severely weakened host trees. When their population densities are high, some species aggregate on healthy host trees so that their defences may be exhausted and the inner bark successfully colonized, killing the tree in the process. Here we investigate under what conditions participating with unrelated conspecifics in risky mass attacks on living trees is an adaptive strategy, and what this can tell us about bark beetle outbreak dynamics. We find that the outcome of individual host selection may deviate from the ideal free distribution in a way that facilitates the emergence of tree-killing (aggressive) behavior, and that any heritability on traits governing aggressiveness seems likely to exist in a state of flux or cycles consistent with variability observed in natural populations. This may have implications for how economically and ecologically important species respond to environmental changes in climate and landscape (forest) structure. The population dynamics emerging from individual behavior are complex, capable of switching between “endemic” and “epidemic” regimes spontaneously or following changes in host availability or resistance. Model predictions are compared to empirical observations, and we identify some factors determining the occurrence and self-limitation of epidemics.
Forfattere
Julie Nåvik Hval Misty Freeman Kristin Kovar Karen LandmanSammendrag
Det er ikke registrert sammendrag
Forfattere
Ellen Henrikke Aalerud Megan Carroll Shana Hirsch Terence Merritt Luis Sevilla Tarek SolimanSammendrag
Det er ikke registrert sammendrag
Forfattere
Signe Kynding Borgen Arne Grønlund Olof Andrén Thomas Kätterer Lars Bakken Keith PaustianSammendrag
Monitoring changes in soil organic carbon (SOC) is not only linked to atmospheric CO2 dynamics, but also to the sustainability of agricultural systems, maintaining food security, reducing water pollution and soil erosion. In accordance with the methodology of the Intergovernmental Panel for Climate Change (IPCC), we developed a Tier 2 method for estimating CO2 emissions from cropland on mineral soils in Norway and compared the results with those of a Tier 1 method. As in most countries, long-term C stock or emission data sets useful for generating factors are scarce in Norway. We used a soil C balance model (ICBM) to calculate country-specific C stock change factors for relevant management systems. Agricultural activity data for 31 agrozones, from 58 ºN to 71ºN, was applied to estimate annual net CO2 emissions from 1999 to 2009. Calculated annual net emissions were larger when estimated by the Tier 2 method than Tier 1 because i) Tier 2-generated stock change factors for crop rotations with animal manure application were larger than the Tier 1 default values and ii) major changes in agricultural management during the inventory period led to a reduction in manure availability. We conclude that model-based Tier 2 methods are promising when empirical data are limited, but activity data, especially regarding animal manure practices (application rates and crop rotation preferences) are crucial for emission estimates by the IPCC methods.
Forfattere
Jihong Liu ClarkeSammendrag
Det er ikke registrert sammendrag
Forfattere
Christian Guido Bruckner Jana Lange Stephanie Markert Kerstin Mammitzsch Günter Jost Dörte Becher Thomas Schweder Matthias Labrenz Klaus JürgensSammendrag
Det er ikke registrert sammendrag
Sammendrag
Det er ikke registrert sammendrag
Forfattere
Sissel Torre Knut Asbjørn Solhaug Meseret Tesema Terfa Jorunn Elisabeth Olsen Christopher Rodriguez G Goutam Aruppillai Suthaparan Arne Stensvand Leiv M. Mortensen Hans Ragnar GislerødSammendrag
Det er ikke registrert sammendrag
Forfattere
Anette Aamodt Moldestad Bernt Hoel Anne Kjersti UhlenSammendrag
Det er ikke registrert sammendrag