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.
2017
Sammendrag
Rapporten beskriver, og gir resultater fra, «Overvåkingsprogrammet for skog i verneområder» som omfatter nasjonalparker og naturreservater som var etablert pr. 1.1.2016. Registreringene ble gjennomført av Landsskogtakseringen i perioden 2012-2016. Statistikk for arealtyper, skogtilstand og miljøverdier som er viktig for biologisk mangfold sammenstilles...
Forfattere
Jostein FrydenlundSammendrag
Det er ikke registrert sammendrag
Forfattere
Christina SoggeSammendrag
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Forfattere
Isabella Børja Volkmar Timmermann Ari Hietala Mari Mette Tollefsrud Nina Elisabeth Nagy Adam Vivian-Smith Hugh Cross Jørn Henrik Sønstebø Tor Myking Halvor SolheimSammendrag
In Norway the common ash (Fraxinus excelsior L.) has its northernmost distribution in Europe. It grows along the coastal range as small fragmented populations. The first occurrence of ash dieback caused by Hymenoscyphus fraxineus in Norway was reported in 2008. At that time, the disease had already spread through large areas of southern and south-eastern parts of Norway. Since then the disease continued spreading with a speed of about 50- 60 km per year along the western coastal range. To monitor the disease development over time, we established eight permanent monitoring plots in south-eastern and western Norway in 2009 and 2012, respectively. In all plots tree mortality was high, especially among the youngest trees in south-eastern Norway. The extent of crown damage has continually increased in all diameter classes for both regions. In 2009, 76.8 % of all trees on the five monitoring plots in south-eastern Norway were considered to be healthy or slightly damaged, and only 8.9 % to be severely damaged. In 2015, 51.7 % were dead, 13.5 % severely damaged and only 25.7 % remained healthy or slightly damaged. To assess the infection pressure and spore dispersal patterns of the pathogen, we used a Burkard volumetric spore sampler placed in an infested ash stand in southern Norway. We examined the airborne ascospores of H. fraxineus and H. albidus captured on the sampling tape microscopically and with real-time PCR assays specific to these fungi. We detected very few ascospores of H. albidus, whereas ascospores of H. fraxineus dominated throughout entire sampling periods of 2009, 2010 and 2011. Spore discharge occurred mainly between the hours of 5 and 8 a.m., though the distinctive sporulation had yearly variation between 5-7 a.m. We observed the same diurnal pattern throughout the entire sampling period, with a seasonal peak in spore liberation between mid-July and midAugust, after which the number of ascospores decreased substantially. Similar diurnal patterns were observed throughout the sampling period except that after mid-August the number of trapped ascospores substantially decreased. To compare the genetic pattern of common ash in the northern and central ranges of Europe we analyzed the Norwegian samples together with available samples from central Europe by using chloroplast and nuclear microsatellite markers. We found that the northern range of common ash was colonized via a single migration route that originated in eastern or south-eastern Europe with little influence originating from other southern or western European refugia. In the northern range margins, genetic diversity decreased and population differentiation increased, coherent with a post-glacial colonization history characterized by founder events and population fluctuations. Based on our findings we discuss the future management and conservational implications.
Sammendrag
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Forfattere
Volkmar TimmermannSammendrag
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Sammendrag
Askeskuddsjuke forårsakes av en liten sopp, Hymenoscyphus fraxineus, på norsk kalt askeskuddbeger. Sjukdommen har i løpet av kort tid spredd seg over store deler av Europas askeskoger. Soppen er en fremmed art som trolig stammer fra Asia hvor den er assosiert med asketrær som er nær beslektet med europeisk ask. Det er særlig unge trær som er utsatt, men også eldre trær kan drepes over tid. Mye er uklart angående hvordan soppen infiserer, men sporene spres med vind til bladene på asketrær. Dersom soppen klarer å vokse forbi bladfestet før bladfall vil den i løpet av vinteren angripe greinene. Typiske symptomer er sår i barken og døde skudd.
Forfattere
Halvor SolheimSammendrag
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Sammendrag
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Forfattere
Hans Petersson Johannes Breidenbach David Ellison Sören Holm Anders Muszta Mattias Lundblad Göran R. StåhlSammendrag
Many parties to the United Nation's Framework Convention on Climate Change (UNFCCC) base their reporting of change in Land Use, Land-Use Change and Forestry (LULUCF) sector carbon pools on national forest inventories. A strong feature of sample-based inventories is that very detailed measurements can be made at the level of plots. Uncertainty regarding the results stems primarily from the fact that only a sample, and not the entire population, is measured. However, tree biomass on sample plots is not directly measured but rather estimated using regression models based on allometric features such as tree diameter and height. Estimators of model parameters are random variables that exhibit different values depending on which sample is used for estimating model parameters. Although sampling error is strongly influenced by the sample size when the model is applied, modeling error is strongly influenced by the sample size when the model is under development. Thus, there is a trade-off between which sample sizes to use when applying and developing models. This trade-off has not been studied before and is of specific interest for countries developing new national forest inventories and biomass models in the REDD+ context. This study considers a specific sample design and population. This fact should be considered when extrapolating results to other locations and populations.