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
Gisela Lüscher Youssef Ammari Aljona Andriets Siyka Angelova Michaela Arndorfer Debra Bailey Katalin Balázs Marion Bogers R.G.H. Bunce Jean-Philippe Choisis Peter Dennis Mario Díaz Tetyana Dyman Sebastian Eiter Wendy FjellstadSammendrag
Det er ikke registrert sammendrag
Forfattere
Sabine Rosner Jan Světlík Kjell Andreassen Isabella Børja Lise Dalsgaard Robert Evans Saskia Luss Ole Einar Tveito Svein SolbergSammendrag
Top dieback in 40–60 years old forest stands of Norway spruce [Picea abies (L.) Karst.] in southern Norway is supposed to be associated with climatic extremes. Our intention was to learn more about the processes related to top dieback and in particular about the plasticity of possible predisposing factors. We aimed at (i) developing proxies for P50 based on anatomical data assessed by SilviScan technology and (ii) testing these proxies for their plasticity regarding climate, in order to (iii) analyze annual variations of hydraulic proxies of healthy looking trees and trees with top dieback upon their impact on tree survival. At two sites we selected 10 tree pairs, i.e., one healthy looking tree and one tree with visual signs of dieback such as dry tops, needle shortening and needle yellowing (n = 40 trees). Vulnerability to cavitation (P50) of the main trunk was assessed in a selected sample set (n = 19) and we thereafter applied SilviScan technology to measure cell dimensions (lumen (b) and cell wall thickness (t)) in these specimen and in all 40 trees in tree rings formed between 1990 and 2010. In a first analysis step, we searched for anatomical proxies for P50. The set of potential proxies included hydraulic lumen diameters and wall reinforcement parameters based on mean, radial, and tangential tracheid diameters. The conduit wall reinforcement based on tangential hydraulic lumen diameters ((t/bht)2) was the best estimate for P50. It was thus possible to relate climatic extremes to the potential vulnerability of single annual rings. Trees with top dieback had significantly lower (t/bht)2 and wider tangential (hydraulic) lumen diameters some years before a period of water deficit (2005–2006). Radial (hydraulic) lumen diameters showed however no significant differences between both tree groups. (t/bht)2 was influenced by annual climate variability; strongest correlations were found with precipitation in September of the previous growing season: high precipitation in previous September resulted in more vulnerable annual rings in the next season. The results are discussed with respect to an “opportunistic behavior” and genetic predisposition to drought sensitivity.
Forfattere
Belachew Gizachew Zeleke Svein Solberg Erik Næsset Terje Gobakken Ole Martin Bollandsås Johannes Breidenbach Eliakimu Zahabu Ernest William MauyaSammendrag
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Forfattere
Lise Dalsgaard Holger Lange Line Tau Strand Ingeborg Callesen Signe Kynding Borgen Jari Liski Rasmus AstrupSammendrag
Soil organic carbon (C), accumulated over millennia, comprise more than half of the C stored in boreal and temperate forest landscapes. We used the Norwegian national forest inventory and soil survey network (n = 719, no deep organic soils) to explore the validity of a deterministic model representation of this pool (Yasso07). We statistically compared simulated and measured soil C stocks and related differences (measured – simulated) to site factors (drainage, topography, climate, vegetation, C-to-N ratio, and soil classification). Median C stocks were 5.0 kg C·m−2 (model) and 14.5 kg C·m−2 (measurements). Soil C differences related to site factors (r2 of 0.16 to 0.37). For Brunisols, Gleysols, and wet Organic soils, differences related primarily to topographic wetness. For Regosols, Podzols, and Dystric Eluviated Brunisols, they related to climate, profile depth, and, in some cases, drainage class and site index. We argue that soil moisture regimes in our study area overrule tree productivity effects in the determination of soil C stocks and present conditions for soil formation that the model cannot (and does not explicitly) account for. These are processes such as humification and podsolization that involve eluviation and illuviation of dissolved organic C (DOC) with sesquioxides to form spodic B horizons and carbon enrichment due to hampered decomposition in frequently anoxic conditions.
Sammendrag
A controlled climatic chamber microcosm experiment was conducted to examine how light affects the hourly sporulation pattern of the beneficial mite pathogenic fungus Neozygites floridana during a 24 h cyclus over a period of eight consecutive days. This was done by inoculating two-spotted spider mites (Tetranychus urticae) with N. floridana and placing them on strawberry plants for death and sporulation. Spore (primary conidia) discharge was observed by using a spore trap. Two light regimes were tested: Plant growth light of 150 μmol m−2 s−1 for 12 h supplied by high pressure sodium lamps (HPS), followed by either; (i) 4 h of 50 μmol m−2 s−1 light with similar HPS lamps followed by 8 h darkness (full HPS light + reduced HPS light + darkness) or (ii) 4 h of 50 μmol m−2 s−1 red light followed by 8 h darkness (full HPS light + red light + darkness). A clear difference in hourly primary conidia discharge pattern between the two different light treatments was seen and a significant interaction effect between light treatment and hour in day during the 24 h cycle was observed. The primary conidia discharge peak for treatment (ii) that included red light was mainly reached within the red light hours (19:00–23:00) and the dark hours (23:00–07:00). The primary conidia discharge peak for treatment (i) with HPS light only was mainly reached within the dark hours (23:00–07:00).
Forfattere
Ingerd Skow Hofgaard Till Seehusen Heidi Udnes Aamot Hugh Riley Jafar Razzaghian Vinh Hong Le Anne-Grete Roer Hjelkrem Ruth Dill-Macky Guro BrodalSammendrag
Det er ikke registrert sammendrag
Forfattere
Ingerd Skow Hofgaard Heidi Udnes Aamot Torfinn Torp M. Jestoi V.M.T. Lattanzio Sonja Klemsdal C. Waalwijk T. van der Lee Guro BrodalSammendrag
During the last ten years, Norwegian cereal grain industry has experienced large challenges due to Fusarium spp. and Fusarium mycotoxin contamination of small-grained cereals. To prevent severely contaminated grain lots from entering the grain supply chain, it is important to establish surveys for the most prevalent Fusarium spp. and mycotoxins. The objective of our study was to quantify and calculate the associations between Fusarium spp. and mycotoxins prevalent in oats and spring wheat. In a 6-year period from 2004-2009, 178 grain samples of spring wheat and 289 samples of oats were collected from farmers’ fields in South East Norway. The grains were analysed for 18 different Fusarium-mycotoxins by liquid chromatography – mass spectrometry. Generally, the median mycotoxin levels were higher than reported in Norwegian studies covering previous years. The DNA content of Fusarium graminearum, Fusarium culmorum, Fusarium langsethiae, Fusarium poae and Fusarium avenaceum were determined by quantitative PCR. We identified F. graminearum as the main deoxynivalenol (DON) producer in oats and spring wheat, and F. langsethiae as the main HT-2 and T-2-toxins producer in oats. No association was observed between quantity of F. graminearum DNA and quantity of F. langsethiae DNA nor for their respective mycotoxins, in oats. F. avenaceum was one of the most prevalent Fusarium species in both oats and spring wheat. The following ranking of Fusarium species was made based on the DNA concentrations of the Fusarium spp. analysed in this survey (from high to low): F. graminearum = F. langsethiae = F. avenaceum > F. poae > F. culmorum (oats); F. graminearum = F. avenaceum > F. culmorum > F. poae = F. langsethiae (spring wheat). Our results are in agreement with recently published data indicating a shift in the relative prevalence of Fusarium species towards more F. graminearum versus F. culmorum in Norwegian oats and spring wheat.
Sammendrag
Det er ikke registrert sammendrag
Forfattere
Rasmus John Normand Frandsen Silas A. Rasmussen Peter B. Knudsen Silvio Uhlig Dirk Petersen Erik Lysøe Charlotte H. Gotfredsen Henriette Giese Thomas O. LarsenSammendrag
Biosynthesis of the black perithecial pigment in the filamentous fungus Fusarium graminearum is dependent on the polyketide synthase PGL1 (oPKS3). A seven-membered PGL1 gene cluster was identified by over-expression of the cluster specific transcription factor pglR. Targeted gene replacement showed that PGL1, pglJ, pglM and pglV were essential for the production of the perithecial pigment. Over-expression of PGL1 resulted in the production of 6-O-demethyl-5-deoxybostrycoidin (1), 5-deoxybostrycoidin (2), and three novel compounds 5-deoxybostrycoidin anthrone (3), 6-O-demethyl-5-deoxybostrycoidin anthrone (4) and purpurfusarin (5). The novel dimeric bostrycoidin purpurfusarin (5) was found to inhibit the growth of Candida albicans with an IC50 of 8.0 +/− 1.9 μM. The results show that Fusarium species with black perithecia have a previously undescribed form of 5-deoxybostrycoidin based melanin in their fruiting bodies.
Sammendrag
Abstract Questions Vegetation mapping based on field surveys is time-consuming and expensive. Distribution modelling might be used to overcome these challenges. What is the performance of distribution modelling of vegetation compared to traditional vegetation mapping when projected locally? Does the modelling performance vary among ecosystems? Does vegetation type distribution and abundance influence the modelling performance? Location Gravfjellet, Øystre Slidre commune, southern Norway. Methods Two comparable neighbouring areas, each of 4 km2, were mapped for species-defined vegetation types. One area was used for model training, the other for model projection. Maximum entropy models were run for six vegetation types, two from each of the ecosystems present in the area: forest, wetland and mountain heath- and shrublands. For each ecosystem, one locally abundant and one locally rare vegetation type were tested. AUC, the area under the receiver operating curve, was used as the model selection criterion. Environmental variables (n = 9) were selected through a backwards selection scheme, and model complexity was kept low. The models were evaluated using independent data. Results Distribution modelling of vegetation types by local projection gave high AUC values, and the results were supported by the evaluation using independent data. The modelling ability was not affected by ecosystem differences. A negative relationship between the number of points used to train the models and the AUC value before evaluation suggests that models for locally rare vegetation types had better predictive performance than the models for abundant types. This result was not significant after evaluation. Conclusion Provided that relevant explanatory variables are available at an appropriate scale, and that field-validated training points are available, distribution modelling can be used for local projection of the six tested vegetation types from the boreal–alpine ecotone.