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.
2009
Sammendrag
European ash (Fraxinus excelsior), also known as common ash, occurs naturally inland in lower areas of southeastern Norway and along the southern coast of the country. It is important both as a forest and ornamental tree. During the last decade, dieback has become a disastrous disease on F. excelsior in many European countries. The anamorphic fungus Chalara fraxinea T. Kowalski (1), described for the first time from dying ash trees in Poland, is now considered the cause of ash dieback (2). In May of 2008, C. fraxinea was isolated from 1.5 m high diseased F. excelsior in a nursery in Østfold County in southeastern Norway. Symptoms included wilting, necrotic lesions around leaf scars and side branches, and discoloration of the wood. From symptomatic branches, small pieces (approximately 1 cm3) were excised in the transition area between healthy and discolored wood. After surface sterilization (10 s in 70% ethanol + 90 s in NaOCl), the pieces were air dried for 1 min in a safety cabinet, cut into smaller pieces, and placed on media. The fungus was isolated on potato dextrose agar (PDA) and water agar (WA). On PDA, the cultures were tomentose, light orange, and grew slowly (21 mm mean colony diameter after 2 weeks at room temperature). Typical morphological features of C. fraxinea developed in culture. Brownish phialides (14.8 to 30.0 [19.5] × 2.5 to 5.0 [4.1] μm, n = 50) first appeared in the center of the colonies on the agar plugs that had been transferred. The agar plugs were 21 days old when phialides were observed. Abundant sporulation occurred 3 days later. Conidia (phialospores) extruded apically from the phialides and formed droplets. Conidia measured 2.1 to 4.0 (3.0) × 1.4 to 1.9 (1.7) μm (n = 50). The first-formed conidia from each phialide were different in size and shape from the rest by being longer (6 μm, n = 10) and more narrow in the end that first appeared at the opening of the phialide. Internal transcribed spacer sequencing confirmed that the morphological identification was correct (Accession No. EU848544 in GenBank). A pathogenicity test was carried out in June of 2008 by carefully removing one leaf per plant on 10 to 25 cm high F. excelsior trees (18 trees) and placing agar plugs from a 31-day-old C. fraxinea culture (isolate number 10636) on the leaf scars and covering with Parafilm. After 46 days, isolations were carried out as described above from discolored wood that had developed underneath necrotic lesions in the bark and subsequently caused wilting of leaves. All the inoculated plants showed symptoms, and C. fraxinea was successfully reisolated. No symptoms were seen on uninoculated control plants (eight trees) that had received the same treatment except that sterile PDA agar plugs had been used.
Forfattere
Jarl-Gunnar Salin Peder GjerdrumSammendrag
Wooden poles are frequently used for power and telecommunication lines. After creosote preservation the durability is secured for many decades. This study is related to a Norwegian plant where such poles are produced using Scots pine. Prior to the preservation process the poles have to be dried to a moisture content below the fibre saturation point everywhere in the pole. This is done outdoors in open stacks of poles, i.e. as air-drying. A problem is caused by the difficulties to determine when the target moisture content has been reached. The inventory of drying poles represents considerable value in a company\"s balance sheet and risk of downgrading. Knowledge of drying times during the annual seasons has been insufficient, and no efficient method is known for accurately observing the MC through the various parts of the poles.....
Sammendrag
Evaluation of climate change consequences and national carbon reporting such as under the Kyoto protocol require long-term monitoring of carbon fluxes. We report on an ongoing project aimed at a national-level assessment of the terrestrial carbon sequestration potential under present conditions and under various climate and land use change scenarios, in particular in terms of their temperature effect. We develop empirical models for national soil carbon stock assessment and evaluate process-based soil carbon models for prediction of future carbon dynamics.....
Sammendrag
The CO2 uptake of the terrestrial biosphere (Gross Primary Productivity, GPP) plays a key role in the global carbon balance. This carbon flux cannot be determined directly on a global scale. Yet, the remotely sensed Fraction of Absorbed Photosynthetically Active Radiation (FAPAR) is a valuable proxy for GPP. This study aims at characterizing global FAPAR dynamics on different temporal scales and extracting corresponding spatial structures. The time series were analyzed to uncover the presence and extent of trends, and to identify quasi-oscillatory patterns from intra- to interannual time scales....
Sammendrag
In high-latitude areas, landscapes with flat or moderate relief areas usually contain lakes and mires. The identification of flowpaths in such areas is a difficult issue. The increasing availability of high resolution topography from airborne Lidar measurements offers new opportunities for automatic or semi-automatic channel extraction from DEMs in small watersheds, substantially outperforming the hydrographic network in conventional digital maps....
Sammendrag
Stream flow observations from a geographical region are known to often exhibit strong common behavior. In order to assess the temporal evolution of the complexity of stream flow time series from all over Europe, we employ the recently developed Linear Variance Decay dimension density (δLV D). It is estimated as the parameter of an exponential decay function fitted to the remaining variances of the eigenvalues of a covariance matrix. Scaling between zero and one, δLV D can be interpreted as a measure of the proportion of linear independent components in a multivariate record.....
Forfattere
Ulf Sikström Staffan Jacobson Ulf Johansson Mikko Kukkola Anna Saarsalmi Kjersti Holt HanssenSammendrag
Forest based bioenergy is important in the Nordic countries. Growth increment usually decreases somewhat after whole tree harvesting, where branches and tops are removed and used for bioenergy. Ash recycling is recommended in Sweden, to re-allocate some of the nutrients removed in whole tree harvesting. In this report a preliminary analysis of ash and lime experiments on mineral soil in Sweden, Finland and Norway was performed. Trends in the material indicated reduced growth at sites with low site index after ash or lime addition, while sites with medium site index showed no change, and growth increased at high site indices. No significant correlations were found between ash or lime fertilization and C/N ratio in the humus layer. The material will be further analysed in an ongoing project.
Forfattere
Tor Myking Per Arild Aarrestad John Derome Vegar Bakkestuen Jarle Werner Bjerke Michael L. Gytarsky Ludmila Isaeva Rodion Karaban Vladimir Korotkov Martti Lindgren Antti-Jussi Lindroos Ingvald Røsberg Maija Salemaa Hans Tømmervik Natalya VassilievaSammendrag
The effect of air pollution from the Petchenganickel industrial complex, northwestern part of the Kola Peninsula, on forest vegetation was studied by combining three dormant monitoring networks in Finland, Russia and Norway, comprising a total of 21 plots that were revisited in 2004. Chemical composition of precipitation was monitored during 2004–2005, and indicated continuing high deposition of heavy metals and SO2 in the border area. The cover of epiphytic lichens on the trunks of downy birch (Betula pubescens) and Scots pine (Pinus sylvestris) was severely affected by pollution, and there was also a consistent negative effect on the abundance and richness of lichens and bryophytes on the forest floor in a more limited area. The effects of pollution on crown condition and stand growth were weak or absent. This study is an important reference for evaluating the effects of the planned renovation of the smelter in Nikel.
Forfattere
Oddvar Haveraaen Jørn Heggertveit Arne SandnesSammendrag
Høydeutvikling ble studert i bestand gjennom uttak av stammeskiver fra overhøydetrær. Produksjonen beregnet vi etter omfattende registrering i relativt unge og tette bestand ved anlegg og revisjon seks år seinere. De permanente flatene besto av to eller tre ruter; ei kontrollrute (T0), og ei eller to ruter som ble tynnet, svakt (T1) og/eller sterkt (T2). Høydeutviklingen hos svartor samsvarte godt med boniteringskurver for svartor i Mellom-Europa og Sverige. Disse har totalalder som inngang, mens det i Norge er vanlig med alder i brysthøyde. Sammenligningen med de norske bonitetskurvene for bjørk og osp var god fra henholdsvis 20 og 10–15 år og framover, men før den tid gir de en underbonitering. Avvikene var noe større for gråor og ask innen samme tidsperioder....
Forfattere
Carl Gunnar Fossdal Igor A. Yakovlev Ari M. Hietala Halvor SolheimSammendrag
To identify differentially expressed genes of the white-rot fungus Heterobasidion parviporum subtractive cDNA libraries were constructed using suppressive subtraction hybridization (SSH) technique with RNA extracted from an advanced stage of decay area and from colonization front next to the reaction zone of the stem of a mature Norway spruce trees. Besides cytochrome P450s and proteins with unknown function, the SSH libraries constructed contained genes involved in basic cellular processes, andcell wall degradation. To examine the role of selected candidate genes three trees, showing a variable degree of wood decay, were used for real-time RT-PCR profiling of candidate genes. In the decay transition areas the study revealed activity centers that showed remarkable similarity in the transcript profiles of monitored genes.