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.
2001
Forfattere
R. Bach B. BraskerudSammendrag
Fangdammene Selte, Fossum og Vaker ligger i Steinsfjordens nedbørsfelt på Ringerike 4 mil nordvest for Oslo. På oppdrag fra Hole og Ringerike kommune, har Jordforsk målt tilbakeholdelsen av sediment og fosfor i dammene fra 1996-2000. Fangdammene består av følgende komponenter: sedimentasjonskammer, våtmarksfiltre og overrislingssoner. Terrengforholdene har gjort at utformingen er ulik. Tilbakeholdelsen av sediment og fosfor i både Selte, Fossum og Vaker er målt ved årlig prøvetaking av sedimentoppbygging i sedimentasjonskamre og våtmarksfiltrene. Steinslettas landbruksareal er lite erosjonsutsatt. Sedimentasjonsmengden varierer mellom fangdammene, og fra år til år. Det skyldes forskjeller i fangdammenes størrelse og tilførsler fra nedbørsfeltet. I prøvetakingsperioden på 5 år er det holdt tilbake 173 tonn jord og 170 kg fosfor i Selte. I Fossum er det holdt tilbake 61 tonn jord og 49 kg fosfor. I Vakers sedimentasjonskammer har den totale tilbakeholdelsen vært på 591 tonn jord og 589 kg fosfor. Våtmarksfiltrene har totalt holdt tilbake 64 tonn jord og 57 kg fosfor. Det ser ut som om mengden tilbakeholdt jord og fosfor har lagt seg på et høyere nivå de siste 3 årene av prøvetakingsperioden for alle dammene. Årsaken til dette kan være økt erosjon på grunn av mer nedbør. Oppfyllingshastigheten varierer, men det vil trolig være nødvendig med tømming i flere av anleggene i løpet av en 10 års periode. Stofftapet fra Steinsletta og Åsa ligger på grenseverdien 12-72 kg jord/da i områder med slake hellinger. I brattere terreng ligger grenseverdiene på 125-747 kg jord/da.
Forfattere
Bjørn Ivar HonneSammendrag
For a diploid one locus two alleles model it is shown that the parameter space for all possible genotypic compositions of the population is a triagle. The hardy-Weinberg equilibrium is a borderline between the area with excess of homozygotes, comprising 2/3 of the total, and the area with deficiency of homozygotes, 1/3 of the total. A generalized model for factorial mating is used to show that the within family genetic variance is a function of the frequency of heterozugous parents. The exposed additive genetic variance and the GCA among families from polycrosses will therefore increase with an excess of homozygous parents compared to H-W-equilibrium frequencies. It is shown that dividing breeding populations into subpopulations leads to this excess, and a simulation study indicates that GCA on the average will increase about 35% with subdivision of the breeding population. A breeding strategy, with recurrent selection and production of synthetics which utilises this, is described.
Forfattere
Aksel GranhusSammendrag
The risk of logging damage to residual trees (height >3.0 m) and advance regeneration saplings (height 0.5–3.0 m) was evaluated after mechanized (single-grip harvesters + forwarders) and motor-manual (chain saw + skidding) selection harvesting in studies I and II. Harvesting took place during the winter season. Mechanized harvesting caused the highest injury rates, and the difference was highest at high cutting intensity in densely stocked stands. Another important difference between the two operating methods was the spatial distribution of the injury risk relative to striproads. The most important injuries on the larger (>3.0 m) trees were stem- and root wounds, and loss of branches. Wounds tended to be larger, and crown injuries more serious, after mechanized harvesting, but differences were not statistically significant. The most frequent injuries on saplings were crown injuries (loss of branches, stem breakage) and stem lean. In motor-manually harvested stands saplings without pre-harvest deformities in the form of top- or leader defects were more prone to damage than saplings with such defects. A similar difference was not found in stands subjected to mechanized harvesting. This result was attributed to the different work patterns during felling and processing with the two operating methods, in combination with the spatial distribution of saplings of different quality relative to larger trees and stand openings. In study III sapling mortality, and recovery from logging damage in a five-year period after selection harvesting, was investigated. Mortality on the different plots (n=11) was highly variable. For saplings without previous logging damage mortality was related to pre-harvest vigour, and increased with increasing cutting intensity in the immediate surrounding of the sapling. Unspecified site factors also contributed to explain the probability of mortality. Saplings that had been pushed over during harvesting often survived and recovered, while injuries to the crown led to poor survival. Crown injuries were most common on plots subjected to mechanized harvesting, while stem lean was correspondingly important on motor-manually harvested plots. Whether this pattern was attributed to differences in temperature at the time of harvesting (winter), or operating method, is uncertain. In study IV advance regeneration responses in terms of height growth, needle dry weights, and foliar nutrient concentrations were compared after three different release treatments: untouched control, selection harvesting with 50-60 % removal of basal area (BA50-60), and patch cut (25x25 m - 0.063 ha clear-cut). The foliar analyses were carried out five years after treatment, and included dominant and co-dominant (overstorey) trees on control and BA50-60 plots. Height growth and needle dry weights of saplings generally increased with increasing overstorey removal. The growth response was explained by an interaction of foliar nitrogen concentration in current (C) and one-year-old (C+1) needles, and degree of overstorey removal. The foliar analyses did, however, not confirm improved N status after cutting. Increasing overstorey removal led to a reduction of K (C), Mg (C+1) and B (C, C+1) in saplings. A parallel decline of B (C+1) occurred in the overstorey trees (BA50-60). Saplings on control plots had higher concentrations of K and Cu in C-needles, relative to overstorey trees. The influence of neighbour tree basal area on sapling height growth and presence of natural defects (top- and leader damage) was examined in study V. The three stands selected for the study had not been subjected to cutting for several decades, and basal areas ranged from 25–33 m2 ha-1. The relationship between growth and four basal area variables was evaluated: basal area (m2 ha-1) of taller (>3.0 m) neighbour trees within 2.82, 3.99 and 5.64 m radius from the sapling (25, 50 and 100 m2 circular plots), and basal area (m2) of trees within 5.64 m radius weighted according to distance from the sapling. A reduction of growth attributed to increasing basal area of neighbour trees was only observed for the tallest saplings (2.1-3.0 m). Between 33 and 42 % of the saplings had leader- or top defects, and damage frequencies increased with declining distance to the nearest taller neighbour tree.
Forfattere
Lars Sandved Dalen M. GriffithSammendrag
Adaptation to cold and freezing temperatures is crucial for survival in temperate and boreal areas. Compared with angiosperms, little is known about the mechanisms of freezing tolerance in gymnosperms. Coniferous species such as Norway spruce (Picea abies L. Karst.) have a wide distribution in boreal areas, indicating a strong ability to adapt to lasting periods of cold and freezing temperatures.Freezing-tolerant perennial plants survive subzero temperatures by forming ice in intercellular spaces and the xylem. Certain proteins associated with pathogen attack have been found to exhibit antifreeze activity, i.e. the ability to bind and modify the growth of ice.In order to study the possible role of pathogenesis-related proteins in development of freezing tolerance in Norway spruce, we looked at the accumulation of chitinases during hardening under both artificial and natural conditions.Our findings show that chitinases and other pathogenesis-related proteins, as well as antifreeze activity, are present in needles of Norway spruce, and that they increase in response to shorter daylengths and cold temperature. It is possible that pathogenesis-related proteins accumulated in conifers during cold acclimation could also exhibit antifreeze activity, and thus play an important role during development of freezing tolerance in perennial plants such as the gymnosperm Norway spruce.
Forfattere
Trygve S. AamlidSammendrag
Tidligere fylkesagronom Per Bjerkø i Vestfold er en av pionerene i norsk frøavl. I dette intervjuet forteller han om utviklinga av frøavlen i Vestfold de siste 40 åra - fra små arealer timotei og rødkløver til landets ledende frøavlsfylke
Forfattere
Ketil HaarstadSammendrag
Det er ikke registrert sammendrag
Sammendrag
Det er ikke registrert sammendrag
Sammendrag
Air pollution induced changes in pine needle chemistry were observed at sample sites in the surroundings of the Pechenganikel smelter. Close to the smelter, elevated concentrations of Ni, Cu and S were found (Ni: 0.7-1 mmol/kg, CU: 0.4-0.5, and S 40-60 mmol/kg) Close to the pollution source needles were enriched in Ni and Cu by needle age. Correlation and principal component analyses show that changes in the element composition of pine needles depended on air pollution and on natural factors as well. The contribution from air pollution increased with needle age. Besides direct input of pollutants from atmosphere, soil contamination and nutritional disturbance contributed significantly to the observed changes.
Forfattere
Øyvind HansenSammendrag
Dette notatet omhandler NILF`s del av det tverrfaglige prosjektet «Planmessig utnytting av utmarksbeite på Senja». Prosjektet er eid av Nattmålshaugen beitelag i Lenvik kommune i Troms. Planteforsk Holt har vært prosjektleder og koordinator for arbeidet i flere institusjoner og organisasjoner som har vært engasjert i prosjektet. Prosjektet kom i gang som et resultat av ønsket om bedre og økt utnytting av utmarksbeitet i beitelaget. Og et behov for økt kunnskap om mange problemstillinger knyttet til bruk av utmarka. Første del av notatet omhandler hva NILF har fått ut av arbeidet med å analysere regnskap og vekter på dyrene fra gårdsbruk i beitelaget. Data fra brukene er sammenlignet med data fra andre registreringer. […]
Sammendrag
In 1998 soil and plant samples of grain and straw from agricultural catchments in Norway, Latvia and Estonia were sampled. No evidence of lack of plant macronutrients was found. Although use of phosphorus and potassium fertiliser is uncommon in Latvia and Estonia, the concentrations of these nutrients in grain samples were not significantly different from Norwegian samples. Analyses of straw samples indicated that potassium fertilisation caused a luxury uptake of potassium in the Norwegian catchments. The calcareous soils with high pH in Latvia and Estonia have higher risks for deficiency of manganese and zinc, than the slightly acid soils in Norway. However, the analyses of pH and extractable Mn in soils, and uptake of Mn in grain indicated that Mn deficiency also could appear in Norwegian soils with pH > 6.3. Although few samples with Zn-concentrations diagnostic for deficiency were found, the correlation between Zn in grain and extractable Zn in soils (0-5 mg Zn/kg) showed that the availability of Zn was of importance for plant uptake. The investigation showed that despite great differences in soils, and fertiliser use between Norway and the Baltic countries Latvia and Estonia, the nutritional value of the cereals was similar.