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.
2007
Forfattere
O. Janne Kjønaas Richard Frederic WrightSammendrag
To determine the source of dissolved inorganic nitrogen (N) in runoff, approx. 35 kg N enriched with the stable isotope 15N (2110‰ δ15N) was added to a mature coniferous forested catchment for one whole year. The total N input was approx. 50 kg ha-1 year-1. The enrichment study was part of a long-term whole-catchment ammonium nitrate addition experiment at Gårdsjön, Sweden. The 15N concentrations in precipitation, throughfall, runoff and upper forest floor were measured prior to, during, and 3-9 years following the 15N addition. During the year of the 15N addition the δ15N level in runoff largely reflected the level in incoming N, indicating that the leached NO3- came predominantly from precipitation. Only 1.1% of the incoming N was lost during the year of the tracer addition. The cumulative loss of tracer N over a 10-year period was only 3.9% as DIN and 1.1% as DON.
Sammendrag
Results from trials with the use of Macrolophus caliginosus on tabacco bankerplants to control whiteflies (Trialeurodes vaporariorum) in cut roses in a commercial greenhouses were presented.
Forfattere
Arne Oddvar Skjelvåg Ole Einar Tveito Inge BjørdalSammendrag
An example is given from a pilot project on a coherent application of soil and weather data to produce crop security estimates of barley. GIS was used to interpolate daily weather elements from a network of weather stations to individually mapped soil type units, oil average less than 1 ha, of arable land. Other model tools are: a soil moisture model to estimate soil drying from the day of snow thaw until sowing date, temperature Run functions to estimate daily advance in phenological development to emergence, heading, and yellow ripeness, and thereafter, a grain moisture model for logging of combine harvesting days, taking also daily precipitation into account. The outcome is probability estimates of getting at least a given number of combining options within a given calendar day.
Sammendrag
Flashiness indeks og base flow indeks ble beregnet for Austenaa og Flaksvatn, to målestasjoner på sørlandet. For Austenaa var det en nedgang i flashiness index men base flow indeks økte over tid. For Flaksvatn var endringer mindre synlig.
Sammendrag
Det er ikke registrert sammendrag
Forfattere
Anne Kristine Søvik P.T. MørkvedSammendrag
Constructed wetlands (CWs) in the agricultural landscape reduce non-point source pollution through removal of nutrients and particles. The mechanisms contributing to removal of nitrogen (N) in CWs are considered to be sedimentation, assimilation in plants and microorganisms, and denitrification. Nitrogen assimilated in wetland vegetation will to a large extent be remineralized sooner or later, unless the vegetation is harvested. Thus, the most important removal mechanism for N and the only one which is permanent is microbial denitrification. Nitrogen removal in ponds is often found to be enhanced in the presence of plants, as denitrification is stimulation by supply of organic material from the plants, which may either be used directly by the denitrifying bacteria or indirectly by contributing to a lower redox potential. However, we still have a limited quantitative knowledge regarding the role of denitrification versus other processes in small CWs, and particularly how this shifts during the year. Biological discrimination between the two stable isotopes 14N and 15N leads to natural iso-topic fractionation, i.e., denitrification yields an enriched pool of 15NO3-, as bacteria preferentially reduce 14NO3- over 15NO3-. The isotopic signature has been used to identify regions of significant denitrification in e.g., groundwater aquifers, riparian buffer zones and CWs. As far as we know, the method has until now only been used in one study regarding constructed wetlands. More studies are needed to identify the limits and possibilities of this method in ecosystems such as CWs.
Forfattere
Arne GrønlundSammendrag
Ikke tilgjengelig
Sammendrag
The relationships between measures of forest structure as derived from airborne laser scanner data and the variation in quantity of young trees established by natural regeneration in a size-diverse spruce forest were analyzed. A regeneration success rate (RSR) was regressed against 27 different laser-derived explanatory variables. The 27 different models were ranked according to their Akaike information criterion score. Each laser variable was then associated with two categories. These were return and type. Within the return and type categories, the variables were grouped according to if they originated from first or last return echoes and if they were canopy height or canopy density metrics. The results show that the laser variables strongest correlated to the quantity of small trees could be attributed to last return and density metrics.
Forfattere
Ole Martin Bollandsås Kjersti Holt Hanssen Solfrid Marthiniussen Erik NæssetSammendrag
The relationships between measures of forest structure as derived from airborne laser scanner data and the variation in quantity of young trees established by natural regeneration in a size-diverse spruce forest were analyzed. A regeneration success rate (RSR) was regressed against 27 different laser-derived explanatory variables. The 27 different models were ranked according to their Akaike information criterion score. Each laser variable was then associated with two categories. These were return and type. Within the return and type categories, the variables were grouped according to if they originated from first or last return echoes and if they were canopy height or canopy density metrics. The results show that the laser variables strongest correlated to the quantity of small trees could be attributed to last return and density metrics.
Forfattere
Mikael Frisk Mikael Rönnqvist Mikael RönnqvistSammendrag
Det er ikke registrert sammendrag