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
Forfattere
Sigmund Hågvar Mikael Ohlson Daniel FløSammendrag
Here, we explore 200 years of arthropod succession by using dated moraines in a Norwegian glacier foreland. Surface active beetles (Coleoptera) and spiders (Aranea) were sampled by pitfall trapping, and springtails (Collembola) and mites (Acari) were extracted from soil samples. Newly deglaciated ground was rapidly colonised by a mixture of generalists and specialists, with various life strategies. Interestingly, the pioneer community was fed by three ‘invisible’ food sources: biofilm with terrestrial diatom algae, tiny pioneer mosses and chironomid midges whose larvae were pond-living and used ancient carbon that was released by the melting glacier as an energy source. The true ‘super-pioneers’ were biofilm-eating springtails, which tracked the melting ice edge closely. Most species of beetles and springtails colonised within 80 years, while spiders and oribatid mites needed a longer time span to colonise. Topography influenced the succession pattern. Among both surface-living macroarthropods and soil-living microarthropods, we distinguished between a ‘dry’ and a ‘wet’ successional pathway with different community structure. Most arthropod species persisted after colonisation, but certain species preferring open space or low temperature were gradually excluded. Comparisons are made with botanical succession. Sampling methods, material size, and taxonomic resolution were considered critical factors when studying arthropod succession.
Sammendrag
Stand dynamics and the gap initiation prior to gap formation are not well- understood because of its long- term nature and the scarcity of late- successional stands. Reconstruction of such disturbance is normally based on historical records and den-droecological methods. We investigated gap initiation and formation at the fine- scale stand level in the old- growth reserve of Karlshaugen in Norway. Given its long- term conservation history, and thorough mapping in permanent marked plots with spatially referenced trees, it provides an opportunity to present stand development before, during, and after gap formation. Late- successional decline in biomass was recorded after more than 50 years of close to steady state. Gaps in the canopy were mainly cre-ated by large old trees that had been killed by spruce bark beetles. Snapping by wind was the main reason for treefall. Long- term dominance of Norway spruce excluded downy birch and Scots pine from the stand. Comparisons of the forest floor soil prop-erties between the gap and nongap area showed significantly higher concentrations of plant available Ca within the gap area. Plant root simulator (PRS™) probes showed significantly higher supply rates for Ca and Mg, but significantly lower K for the gap compared to the nongap area. Soil water from the gap area had significantly higher C:N ratios compared to the nongap area. Fine- scale variation with increasing distance to logs indicated that CWD is important for leaking of DOC and Ca. Our long- term study from Karlshaugen documents gap dynamics after more than 50 years of steady state and a multiscale disturbance regime in an old- growth forest. The observed dis-turbance dynamic caused higher aboveground and belowground heterogeneity in plots, coarse woody debris, and nutrients. Our study of the nutrient levels of the forest floor suggest that natural gaps of old- growth forest provide a long- lasting biogeo-chemical feedback system particularly with respect to Ca and probably also N. Norway spruce trees near the gap edge responded with high plasticity to reduced competition, showing the importance of the edge zone as hot spots for establishing heterogeneity, but also the potential for carbon sequestration in old- growth forest.
Forfattere
Alessio Cibati Bente Føreid Ajay Bissessur Simona HapcaSammendrag
In this work, experimental and modelling investigations were conducted on biochars pyrolyzed at 350 °C and 600 °C, to determine the effect of pyrolysis temperature, hydrogen peroxide activation and pH on copper and zinc removal, in comparison with commercially available activated carbons. Characterization of biochars was performed by BET surface area, elemental analysis and FTIR spectroscopy. Experiments results demonstrated that biochar pyrolyzed at 600 °C adsorbed both copper and zinc more efficiently than biochar pyrolyzed at 350 °C. Chemical activation by H2O2 increased the removal capacity of biochar pyrolyzed at 350 °C. All investigated biochars showed a stronger affinity for copper retention, with a maximum adsorption capacity of 15.7 mg/g while zinc was 10.4 mg/g. The best adsorption performances were obtained at pH 5 and 6. Langmuir adsorption isotherm described copper adsorption process satisfactorily, while zinc adsorption was better described by Freundlich isotherm.
Sammendrag
The Christmas tree industry in Norway is increasing and Abies lasiocarpa is, together with Abies nordmanniana, the most common exotic species for Christmas tree production. A. lasiocarpa today constitutes ca. 50% of the fir sold in Norway, and there is high demand for sufficient supply of high-quality seed and knowledge of seed sources with a potential for high Christmas tree quality. Two experimental plots were established to identify seed sources with potentially high survival and satisfactory Christmas tree quality. The high variation in traits on the two sites indicates promising possibilities for further selection of A. lasiocarpa clones for growing Christmas trees in Norway. Selection for late bud break to avoid spring frost is important. Pathogens were not found in any of the studied trials, but are an important factor to consider when selecting seed sources for Christmas trees. Due to the early bud break of this species, it is also of high importance to choose planting sites with minimal risks for spring frost. Good localities are slopes where the frost drains away during cold nights. In eastern Norway, A. lasiocarpa should be used with care in districts and sites where spring frost is commonly occurring.
Sammendrag
Avrenning fra jordbruket er en viktig kilde til fosfor i vassdrag i Norge. Ulike former for fosfor har ulik effekt på vekst av alger og blågrønnbakterier i vassdragene. I tiltaksanalyser er det derfor viktig å ha pålitelige estimater for både totalfosfor og andelen løst fosfat som tapes fra jordbruket. Vi har brukt data fra ni overvåkingsfelt i Program for jord- og vannovervåking i landbruket (JOVA) som har blitt overvåket i 17-25 år til å kvantifisere konsentrasjonen og andelen løst fosfat av totalfosfor i jordbruksavrenning fra ulike driftssystemer (eng og beite, åpen åker og blandete driftssystemer). Både konsentrasjonen av løst fosfat og andelen løst fosfat av totalfosfor i jordbruksavrenningen varierer sterkt mellom år. Likevel tyder resultatene på at andelen løst fosfat av totalfosfor er høyere i avrenningsvann fra driftssystemer med eng- og beiteareal (43 ± 14 %) enn i avrenningsvann fra blandete driftssystemer (30 ± 15 %) og fra driftssystemer med åpen åker (17 ± 9 %). Driftssystemene med eng- og beiteareal hadde i gjennomsnitt dobbelt så høy husdyrtetthet og høyere nedbør sammenlignet med driftssystemer med åpen åker. Disse resultatene kan bl.a. brukes som grunnlag for vurdering av faktorer for biotilgjengelig fosfor i avrenning fra ulike driftssystemer i jordbruket.
Forfattere
Alemayehu Getachew Assefa Alemayehu Chala Ingerd Skow Hofgaard May Bente Brurberg Michael Sulyok Anne Marte TronsmoSammendrag
The natural occurrence of fungi, mycotoxins and fungal metabolites was investigated in 100 samples of maize grains collected from south and southwestern Ethiopia in 2015. The maize samples were contaminated by Fusarium, Aspergillus and Penicillium species. Using liquid chromatography tandem mass spectrometry 127 secondary metabolites were analysed. Zearalenone was the most prevalent mycotoxin, occurring in about 96% of the samples. Zearalenone sulfate was the second most prevalent, present in 81% of the samples. Fumonisin B1 was detected in 70% of the samples with a mean level of 606 μg kg−1 in positive samples, while FB2, FB3 and FB4 were detected in 62%, 51% and 60% of the maize samples with mean levels of 202, 136 and 85 μg kg−1, respectively. Up to 8% of the samples were contaminated with aflatoxins, with a maximum level of aflatoxin B1 of 513 μg kg−1. Results were higher than earlier reports for maize from Ethiopia.
Sammendrag
Estimates of stand averages are needed by forest management for planning purposes. In forest enterprise inventories supported by remotely sensed auxiliary data, these estimates are typically derived exclusively from a model that does not consider stand effects in the study variable. Variance estimators for these means may seriously underestimate uncertainty, and confidence intervals may be too narrow when a model used for computing a stand mean omits a nontrivial stand effect in one or more of the model parameters, a nontrivial spatial distance dependent autocorrelation in the model residuals, or both. In simulated sampling from 36 populations with stands of different sizes and differing with respect to (i) the correlation between a study variable (Y) and two auxiliary variables (X), (ii) the magnitude of stand effects in the intercept of a linear population model linking X to Y, and (iii) a first-order autoregression in Y and X, we learned that none of the tested designs provided reliable estimates of the within-stand autocorrelation among model residuals. More-reliable estimates were possible from stand-wide predictions of Y. The anticipated bias in an estimated autoregression parameter had a modest influence on estimates of variance and coverage of nominal 95% confidence intervals for a synthetic stand mean.
Sammendrag
Many horse stables have mechanical-fan ventilation systems but still try to regulate ventilation manually by closing doors and windows on a cold winter night. The aim of this study was to investigate the variation in air quality in Norwegian horse stables with different ventilation systems on days with low outdoor air temperatures. A total of 19 insulated, mechanically ventilated stables with horses kept inside during the night were included in the study. Almost all fans were operated during the night (n=18), but inlets for fresh air were highly variable in design and management leading to potential for ineffectiveness of ventilation functions. In four of the stables, there were no specific air inlet systems, and in five stables, the exit door was used as the only air inlet. The air exchange rate was sufficient in all the stables with an automated temperature thermostat for ventilation control. Mean level of carbon dioxide (CO2) was 1,800 ppm and in one stable CO2 exceeded 3,000 ppm. Mean inside ammonia (NH3) was 1.3 ppm, and only in one stable the level of NH3 exceeded 5 ppm. The total dust concentration was 0.69 ± 0.19 mg/m3, and in two stables, the dust concentration exceeded 1.0 mg/m3. Total and respirable dust levels were higher in stables with ventilation rate below recommended level. Half of the stables visited had a lower calculated air exchanges rate than recommended, and the majority of the stables regulated the ventilation manually by closing doors and inlets during night. This indicates a general lack of knowledge among the stable managers of climatic demand in horses and how to operate mechanical ventilation. Still, the majority of the stables maintained acceptable air quality, with NH3 and dust levels within recommended levels, although most stables had elevated humidity.
Sammendrag
Important factors for development of quality defects are the physical, physiological and chemical state of the tubers, which is also described as the maturity status of the crop. The use of maturity indicators as predictors of quality in potato tubers during and after storage was explored in cvs. Asterix and Saturna with three different maturity levels during three years (2010, 2012 and 2013). The maturity indicators measured 1–3 weeks before harvest and at harvest included haulm senescence (haulm maturity), skin set (physical maturity), dry matter content (physiological maturity) and contents of sucrose, glucose and fructose (chemical maturity). Potato quality parameters were measured three times during storage (December, February and April) and included dry matter content, sucrose, glucose and fructose contents, weight loss and fry colour. Cultivar and maturity level were included as categorical predictors in a linear regression model and contributed significantly (P < 0.001) to the models predicting reducing sugars during storage. Dry matter, sucrose, glucose and fructose were included as continuous predictors in the linear regression models and contributed significantly (P < 0.01) to the sucrose, glucose and fructose models and these models explained a high proportion of the variation (R2 ≥ 0.88). Skin set contributed significantly to the weight loss models (P < 0.01) but the models showed low R2 -values (R2 < 0.48). Sucrose contents contributed significantly (P = 0.05) to the fry colour model for Asterix and the fry colour models for both Asterix and Saturna had R2 -values of 0.50 and 0.51 respectively. This study provides new information about the influence of maturity on potato quality during storage and the potential of using field measurements of maturity as predictors of storage potential for processing potato cultivars Asterix and Saturna in Norway.
Sammendrag
The absorption of anthropogenic CO 2 by the oceans is causing a reduction in the pH of the surface waters termed ocean acidification (OA). This could have substantial effects on marine coastal environments where fleshy (non-calcareous) macroalgae are dominant primary producers and ecosystem engineers. Few OA studies have focused on the early life stages of large macroalgae such as kelps. This study evaluated the effects of seawater pH on the ontogenic development of meiospores of the native kelp Macrocystis pyrifera and the invasive kelp Undaria pinnatifi da , in south-eastern New Zealand. Meiospores of both kelps were released into four seawater pH treatments (pH T 7.20, extreme OA predicted for 2300; pH T 7.65, OA predicted for 2100; pH T 8.01, ambient pH; and pH T 8.40, pre-industrial pH) and cultured for 15 d. Meiospore germination, germling growth rate, and gametophyte size and sex ratio were monitored and measured. Exposure to reduced pH T (7.20 and 7.65) had pos itive effects on germling growth rate and gametophyte size in both M. pyrifera and U. pinnatifida , whereas, higher pH T (8.01 and 8.40) reduced the gametophyte size in both kelps. Sex ratio of gametophytes of both kelps was biased toward females under all pH T treatm ents, except for U. pinnatifida at pH T 7.65. Germling growth rate under OA was significantly higher in M. pyrifera compared to U. pinnatifida but gametophyte development was equal for both kelps under all seawater pH T treatments, indicating that the microscopic stages of the native M. pyrifera and the invasive U. pinnatifida will respond similarly to OA.