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.
2016
Forfattere
Mari Mette Tollefsrud Tor Myking Jørn Henrik Sønstebø Vaidotas Lygis Ari Hietala Myriam HeuertzSammendrag
During post glacial colonization, loss of genetic diversity due to leading edge effects may be attenuated in forest trees because of their prolonged juvenile phase, allowing many migrants to reach the colonizing front before populations become reproductive. The northern range margins of temperate tree taxa in Europe are particularly suitable to study the genetic processes that follow colonization because they have been little affected by northern refugia. Here we examined how post glacial range dynamics have shaped the genetic structure of common ash (Fraxinus excelsior L.) in its northern range compared to its central range in Europe. We used four chloroplast and six nuclear microsatellites to screen 42 populations (1099 trees), half of which corresponded to newly sampled populations in the northern range and half of which represented reference populations from the central range obtained from previously studies. We found that northern range populations of common ash have the same chloroplast haplotypes as south-eastern European populations, suggesting that colonization of the northern range took place along a single migration route, a result confirmed by the structure at the nuclear microsatellites. Along this route, diversity strongly decreased only in the northern range, concomitantly with increasing population differentiation and complex population substructures, a pattern consistent with a leading edge colonization model. Our study highlights that while diversity is maintained in the central range of common ash due to broad colonizing fronts and high levels of gene flow, it profoundly decreases in the northern range, where colonization was unidirectional and probably involved repeated founder events and population fluctuations. Currently, common ash is threatened by ash dieback, and our results on northern populations will be valuable for developing gene conservation strategies.
Sammendrag
Large areas of cultivated grasslands have been abandoned in Norway and are no longer used for production. Knowing that access to spring and autumn pastures is a limiting factor for sheep farmers, this study aims at testing the effect of introducing abandoned farmland into sheep production. One sheep ock with 83(88) ewes (lambs) in 2014 and 77 (106) ewes (lambs) in 2015 was each year assigned to three treatments: (1) control; common farm procedure with a short spring grazing period before summer grazing on range pasture; (2) spring extended; a four-week extended spring grazing period on abandoned cultivated grassland before summer grazing on range pasture; (3) whole season grazing on abandoned cultivated grassland. Weight gain from spring to autumn, slaughter weight and carcass value were signicantly (P<0.05) higher in lambs assigned to treatment 2, with four weeks extended spring grazing period (255 g day-1, 15.7 kg, 699 NOK), compared to treatment 1 (229 g day-1, 14.3 kg, 615 NOK) and treatment 3 (206 g day-1, 13.2 kg, 548 NOK). !e use of abandoned cultivated grassland for extended spring grazing improved weight gain and slaughter weight, while whole season grazing on abandoned grassland was the least productive option tested.
Sammendrag
Large areas of cultivated grasslands have been abandoned in Norway and are no longer used for production. Knowing that access to spring and autumn pastures is a limiting factor for sheep farmers, this study aims at testing the effect of introducing abandoned farmland into sheep production. One sheep ock with 83(88) ewes (lambs) in 2014 and 77 (106) ewes (lambs) in 2015 was each year assigned to three treatments: (1) control; common farm procedure with a short spring grazing period before summer grazing on range pasture; (2) spring extended; a four-week extended spring grazing period on abandoned cultivated grassland before summer grazing on range pasture; (3) whole season grazing on abandoned cultivated grassland. Weight gain from spring to autumn, slaughter weight and carcass value were signicantly (P<0.05) higher in lambs assigned to treatment 2, with four weeks extended spring grazing period (255 g day-1, 15.7 kg, 699 NOK), compared to treatment 1 (229 g day-1, 14.3 kg, 615 NOK) and treatment 3 (206 g day-1, 13.2 kg, 548 NOK). !e use of abandoned cultivated grassland for extended spring grazing improved weight gain and slaughter weight, while whole season grazing on abandoned grassland was the least productive option tested.
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Feeding by pine weevil (Hylobius abietis L.) causes severe damage to newly planted conifer seedlings in most parts of Scandinavia. We investigated the effect of planting time and insecticide treatment on pine weevil damage and seedling growth. The main objective was to study if planting in early autumn on fresh clear-cuts would promote seedling establishment and reduce the amount of damage caused by pine weevil the following season. The experiment was conducted in southern Sweden and in south-eastern Norway with an identical experimental design at three sites in each country. On each site, Norway spruce seedlings with or without insecticide treatment were planted at four different planting times: August, September, November and May the following year. In Sweden, the proportion of untreated seedlings that were killed by pine weevils was reduced when seedlings were planted at the earliest time (August/September) compared to late planting in November, or May the following year. This pattern was not found in Norway. The average length of leading shoot, diameter growth and biomass were clearly benefited by planting in August in both countries. Insecticide treatment decreased the number of seedlings killed or severely damaged in both Norway and Sweden.
Sammendrag
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Sammendrag
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Sammendrag
The root rot pathogens in Norway spruce (Picea abies) Heterobasidion ssp. cause substantial loss in carbon sequestered in forest and economic revenue for forest owners. To facilitate strategic breeding planning for increased resistance against this pathogen in particular, the blue stain fungus Endoconidiophora polonica, growth and wood quality traits (wood density and spiral grain), we estimated additive genetic parameters, correlations and the potential response from selection. Parameters were estimated from a progeny trial series established at two sites (25 years from planting) and their parents in a seed orchard (43 years from grafting). A standard half-sib analysis based on progenies and a parent–offspring regression was used for estimation of heritabilities. Resistance against the pathogens was measured as lesion length under bark after inoculations in phloem. Heritability values varied with site and estimation procedure from 0.06 to 0.33, whereas the phenotypic variance (as CV P ) is high and fairly stable around 40–50 %. Heritability values for wood density and spiral grain in the same material varied from 0.32 to 0.63. The highest heritability values were generally obtained from parent–offspring regression. There is no evidence of resistance traits being genetically correlated with growth or wood quality traits. Wood density is negatively correlated with stem diameter. Implications for breeding are discussed.