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
Myrmica specioides Bondroit, 1918 and Formica cunicularia Latreille, 1798 are recorded in Norway for the first time. Both species were found in 2008 at Jeløya, Østfold County in South-Eastern Norway. A total of 54 outdoor-living ant species are now known to occur in Norway.
Forfattere
Ole Martin Eklo Randi Bolli Jens Kværner Tore Sveistrup Frauke Hofmeister Eivind Solbakken Nicolas Jarvis Fredrik Stenemo Eirik Romstad Borghild Glorvigen Tor Anton GurenSammendrag
Det er ikke registrert sammendrag
Sammendrag
Growth of Norway spruce (Picea abies) trees and nitrogen deposition were analysed at about 500 forest plots throughout Norway in six fiveyear periods from 1977 to 2006. Growth was calculated from five repeated calliper measurements of all trees during this period and using treering series from increment cores of a subsample of trees. From the growth data a `relative growth` variable was extracted, being the deviation in % between observed and expected growth rates. The expected growth was estimated from growth models based on site productivity, age and stand density at each plot. The plots were categorized into four age classes. The nitrogen deposition was estimated for each plot for the same five year periods by geographical interpolation of deposition observations at monitoring stations made by the Norwegian Institute for Air Research. Nitrogen deposition from 1977 to 2006 ranged from 1 to 24 kg/ha/yr at the study plots, with about 15 kg/ha/yr in the southernmost region and 3 kg/ha/yr in the northern region of Norway. For the entire 30year period we found a long term relationship between growth and nitrogen deposition, corresponding to a forest growth increase of 0.7% per kg total nitrogen deposition per hectare and year (r2 = 0.13). This is in line with studies carried out on other data sets and for shorter time periods. This apparent fertilizing effect was most pronounced for the youngest forest, while the effect was weak for the oldest forest. The growth increase was observed in the southernmost part of Norway, the region with the highest nitrogen deposition. However, the relationship between nitrogen deposition and growth varied considerably between the time periods. In two of the periods the relationship was slightly negative: these periods corresponded well with summer droughts occurring in the southernmost part of Norway. Drought, as well as other climatic factors, will influence the shortterm variations in forest growth and may obscure the fertilizing effect of nitrogen deposition in some periods. In conclusion, nitrogen deposition has most likely increased growth in Norway spruce in southern Norway. However, our study also shows that inferences from such correlative studies should be drawn with care if the growth period is shorter than 10–15 years because climatic factors produce temporal variations in the relationship between nitrogen deposition and forest growth.
Sammendrag
The chapter reviews the available literature about the adverse effects of excess nickel on plants and their adaptation mechanisms. The study is focused on forest ecosystems exposed to extreme air pollution from the nickel-processing industry in Northern Fennoscandia. Long-term deposition of heavy metals and sulphur has caused strong soil contamination and severe damage to trees and ground vegetation, their structure, composition and chemistry. Tree leaves, branches and bark as well as dwarf shrubs, mosses and lichens show clearly elevated concentrations of nickel and copper in the surroundings of the smelters. Multivariate analyses show that changes in the element composition of plants depend both on air pollution and on natural factors. Besides direct input of pollutants from atmosphere, soil contamination and nutritional disturbance contribute significantly to the observed changes. Despite decline in emissions, extreme pool of heavy metals accumulated in surface soils is expected to influence plant metabolism and chemistry over a long period of time.
Sammendrag
There is a need to establish new objective and sensitive methods for early detection and quantification of decay fungi in wood materials. Molecular methods have proven to be a useful tool within wood protection issues, however, this field is still poorly explored and so far relatively few have used these methods within the field of wood deterioration. Among the techniques used in the indirect quantification of fungi in decayed wood and building material are chitin and ergosterol assays. DNA-based methods are rarely used for identification in connection with quantification. Access to knowledge about fungal colonisation paterns in different wood substrates would allow further improvement of new products. The aim of this study was to investigate the colonisation pattern of decay fungi in wood samples after six years in soil exposure, in an EN252 test.....
Sammendrag
Tree and understorey fine root growth and longevity was determined by minirhizotrone research in northern Finland. The study was made in a 70-year-old Norway spruce stand, growing on a mesic mineral soil site in the Kivalo experimental forest. Three replicate plots were established, and three vertical minirhizotron tubes installed in June 2003 in soil of each of the three plots. The images were taken at monthly intervals (altogether 11 sessions) during the growing seasons 2004, 2005 and 2006. The lengths, diameters and status (new, living, dead, disappeared) of Norway spruce and understorey (mainly shrub) fine roots were recorded. Our data indicates that there were more new roots growing in the upper soil depths (the organic layer) than in the lower soil depths (mineral soil). Roots in the organic layer, however, elongated less than roots in the upper mineral soil. The growth rate was highest in late summer and early autumn. Regarding root longevity, both trees and understorey showed the same trends by root order and soil depth; the average longevity was 14-16 months. The time from death to disappearance was 6-8 months for trees and 2-7 months for understorey. Furthermore, monthly trends of new roots born versus their death and/or disappearance by soil depth are also presented.
Sammendrag
Minirhizotrons, transparent acrylic tubes inserted in the soil, are well suited for long term, non destructive, in situ observations of fine roots. In minirhizotrons, the fine roots are regularly photographed and the root images are visually evaluated according to their status as living, dead or disappeared. This evaluation gives the background for further statistical treatment to estimate the fine root longevity. It is inherent in the minirhizotron technique that a large group of roots will be described as “disappeared” due to grazing, overgrowing by other roots, unclear images or other reasons. Because the fraction of disappeared roots is substantial in some cases, this has consequences for the interpretation of the longevity results. We processed three years of minirhizotron images from Norway spruce stands in southeast Norway (30 yr old) and northern Finland (60 yr old). Of all processed fine roots 32 and 23% was evaluated as disappeared in Norway and Finland, respectively. When roots labelled as disappeared were pooled together with dead ones, the fine root longevity estimates, using the Kaplan Meier method, decreased almost by a factor of two (401 and 433 days), as opposed to labeling them as censored observations (770 and 750 days for Norway and Finland, respectively). Here we demonstrate how the early decision making on the fine root status bears consequences on the resulting longevity estimates. The implications will be discussed
Sammendrag
The soil is considered to be the major Carbon (C) sink in boreal forests, thus determination of soil carbon fluxes is essential for reliable C budgets. Especially partitioning of soil and root respiration is a major challenge. Soil respiration (Rs) consists of autotrophic respiration (Ra, respiration of plant roots and of microorganisms living on root-derived organic C in the rhizosphere) and heterotrophic respiration (Rh, respiration of free-living microorganisms during their decomposition of soil organic matter. In our study we attempted to estimate the contribution of roots to soil respiration by a girdling experiment. The study was established in two Norway spruce (Picea abies) stands, 35 and 65 year old, at Nordmoen, southeast Norway. Four quadratic plots (21m x 21m) were chosen within each of the two stands in spring 2006 and within two plots all trees were girdled. To estimate the contribution of root respiration, we measured CO2 efflux within each plot with a PP EGM-4 gas monitor for CO2, at permanently marked spots during two years (2006 and 2007). In the youngest stand in 2006, Rs in the control plots was higher than in the girdled plots at all measurement occasions. During this period, the mean Rs in the girdled plots was 64.9 % of the mean Rs in the control plots. In 2007, the Rs was highest in the girdled plots on most occasions, but the difference was never significant. In the oldest stand, Rs was also highest in the control plots in 2006 and highest in the girdled stand in most cases in 2007, but the difference was never significant. The implications will be discussed.
Forfattere
Nadeem Yaqoob Igor A. Yakovlev Paal Krokene Harald Kvaalen Halvor Solheim Carl Gunnar FossdalSammendrag
Clonal variation towards resistance has been observed in Norway spruce Heterobasidion annosum s.l. (H.a). H.a. is the main cause of root rot and has a severe economic impact on an economically important conifer tree species. Annual financial losses are in the hundreds of millions of Euros annually. Less susceptible clones appear to have an efficient system of recognizing the pathogen and initiating early defense signalling events. Active defense responses can be started locally and transmitted systemically. This work focus on the expression both spatially (systemically) and temporally in this pathosystem. Two-year-old, somatic saplings of the Norway spruce clone were challenged with H.a., wounded, methyl jasmonate painted and compared to untreated controls and ninety plants were used for the experiment. Stem samples were collected at 1, 3, 6 and 13 days post inoculation (d.p.i). The stem of the saplings were divided into sections along its length and the bark and wood separated from each other at time of collection. In order to see local response an area of 1cm including the site of inoculation was collected, while the spatial (systemic) response was assessed in sections collected at distances of 3 and 6cm away from the site of inoculation. The separated bark and wood were analysed for differential gene expression by qRT-PCR, and the results from peroxidases (PaPX3 and PaPX2) and a chitinase (PaChi4) are presented. Both local and systemic up- and down-regulation were observed at the transcriptional level in both bark and wood, up to 2000 fold local increase in expression was observed for PaChi4.
Sammendrag
Two mature clones of Norway spruce (Picea abies (L.) Karst.) shown to have different level of resistance towards inoculation of Heterobasidion parviporum were compared with respect to spatiotemporal expression of transcripts related to biosynthesis of lignin, stilbenes and other phenolic compounds in response to fungal inoculation and physical wounding. Both clones responded to H. parviporum and physical wounding at transcriptional and chemical levels. Taxifolin, detected in the resistant clone only, increased in concentration following both wounding and inoculation. Concentrations of stilbenoid glucosides were highest in the susceptible clone. Following wounding or inoculation, concentrations of these glucosides increased in the susceptible clone, and quantities of their corresponding aglycones increased dramatically in both clones close to the treatment point. Significant changes in transcription were detected over the entire lesion length for all transcripts, and only the changes in a few transcripts indicated a response to inoculation with H. parviporum differing from that caused by wounding alone. The resistant clone had higher basal concentrations of lignin (LTGA) compared to the susceptible clone; concentrations increased in both clones after wounding and wounding plus inoculation treatments, but remained consistently higher in the resistant clone, suggesting higher lignin levels in the cell walls compared to the susceptible clone. In addition, the transcript level in the same clones was also measured the following year and we saw indications of primed defences for a number of gene products likely resulting from the inoculations performed 12 months prior.