Publications
NIBIOs employees contribute to several hundred scientific articles and research reports every year. You can browse or search in our collection which contains references and links to these publications as well as other research and dissemination activities. The collection is continously updated with new and historical material.
2026
Forfattere
Berger, Lisa MarianneSammendrag
Norway spruce (Picea abies (L.) H. Karst.) is one of the most important tree species in Europe and Norway both ecologically and economically. To produce sufficient seedlings for reforestation and commercial forestry, Norway spruce plants are commonly cultivated in forest nurseries where conditions such as high plant density and humidity may increase susceptibility to pathogen infection. Meanwhile, increasing fungicide resistance and stricter regulations on fungicide use have created a need for alternative and more sustainable disease management strategies. One potential approach is defense priming with the use of methyl jasmonate (MeJA), a plant hormone associated with defense activation. The aim of this study was to investigate the effects of MeJA seed priming on defense-related and physiological responses in Norway spruce seedlings from different provenances. Seeds originating from Aremark, Inderøy and Kilen were treated with MeJA or water (control) prior to sowing. Effects of seed treatment were evaluated through analyses of germination, growth, stomatal characteristics, pigment composition, relative gene expression and resistance to Botrytis cinerea. Relative gene expression of selected defense-related (PaCHI4, PaPAL2, PaTPS-CAR) and photosynthesis-related (PaPSI, PaPSII, PaCHL) genes were quantified using RT-qPCR following mechanical wounding. MeJA treatment significantly reduced seedling growth across provenances and was associated with lower germination in several treatments, suggesting physiological trade-offs related to defense activation. MeJA treatment also affected expression of both defense- and photosynthesis-related genes, including increased expression of PaCHI4 and PaPAL2, as well as altered expression of PaPSI and PaPSII, indicating that seed priming affected both defense and photosynthetic physiology. Mechanical wounding further amplified several of these responses and strongly affected pigment composition and gene expression. Chlorophyll a concentration and chlorophyll a/b ratios were reduced following wounding and MeJA treatment, while carotenoid response varied among provenances. In contrast, stomatal size was not significantly affected by treatment. Following B. cinerea inoculation, MeJA-treated seedlings generally exhibited a tendency toward higher resistance compared to controls, although responses varied among provenances and were not consistently significant. Overall, the results demonstrate that MeJA seed priming influences multiple physiological and molecular processes in Norway spruce seedlings and may enhance inducible defense responses against pathogen stress.
Forfattere
Mong, Åsta DimmenSammendrag
Due to rising concerns over the negative effects from pesticides, nations like Norway have implemented integrated pest management (IPM) in their national strategy to reduce pesticide use. IPM highlights semi-natural habitats (SNH) as key elements in conservation biological control, as they provide essential resources for natural enemies. One of the pests in apple orchards is the codling moth (Tortricidae: Cydia pomonella) and it is known to have developed resistance against a variety of pesticides. The codling moth may be exposed to ground dwelling predators such as carabid beetles (Coleoptera: Carabidae) and spiders (Arachnida: Araneae) during its life stages on the orchard floor. The aim of this study was to explore how semi-natural habitats (SNH) influence ground dwelling predator communities in apple orchards and its possible impacts for biocontrol using the codling moth as an example. By using pitfall traps, this study explored how predator communities varied across a distance gradient from adjacent SNH in three apple orchards in Østfold, Norway throughout one growth season. Results suggest that activity-density, species diversity and richness are influenced by season rather than distance. Carabid communities were found to become less functionally diverse towards the orchard interior as both functional diversity indices decreased with increasing distance.
Forfattere
Christoffersen, BendikSammendrag
Små innløpsbekker som ligger i boreale barskogområder er følsomme for endringer i vannføring og avrenning fra nedbørfeltet. Denne studien undersøker hvordan hydrologi påvirker vannkjemi i fire innløpsbekker til Råsjøen i Sørøst-Norge (60.2°N, 10.8°Ø). Systemet ligger i et område som tidligere har vært påvirket av antropogen forsuring, og systemet som helhet er også i dag påvirket av brunifisering («browning»). Denne studien har fokus på sammenhenger mellom konsentrasjon av vannkjemiske parametere og vannføring modellert ved kovariansanalyse (ANCOVA), effekt av innsjøkalking på vannkjemien i bekkene nedstrøms innsjøene, trender i utvikling for fargetall i bekker og innsjøer (Mann-Kendall), og påvirkning på tetthet av brunørret. Analysene er basert på flere årlige vannprøver (i snitt ~7 vannprøver/år) fra 2015 – 2025, data for fargetall fra Miljødirektoratets database for innsjøer beliggende oppstrøms bekkene i de respektive nedbørfeltene fra 1995 – 2024, målinger av vannføring med saltfortynningsmetoden, vannføringskurver og årlig elektrofiskedata fra 2015 – 2025. De fire undersøkte bekkene varierer i kalkstatus, hvor bekk A har et nedbørfelt hvor alle innsjøene oppstrøm er kalket, bekk B hvor en av to oppstrøms innsjøer er kalket, og bekk C og D hvor ingen av innsjøene oppstrøms er kalket. Økende vannføring hang sammen med lavere pH, syrenøytraliseringskapasitet (ANC) og alkalinitet, og med høyere konsentrasjon av totalt organisk karbon (TOC), fargetall og uorganisk aluminium (Ali) for samtlige bekker. Disse sammenhengene kan tyde på at episoder med høy vannføring øker grunnvannsnivået som i økende grad kobler på strømningsbaner for vannet i grunnere jordlag, hvor innholdet av organisk materiale er større. Dette peker på at surstøtene som inntreffer som konsekvens av økt vannføring er drevet av en samtidig reduksjon av ANC og økt konsentrasjon av organisk materiale løst i vannet, som inneholder en betydelig del organiske syrer. Data fra pH-loggere med høy tidsoppløsning viste hysterese for forholdet mellom pH og vannføring, hvor pH konsekvent var lavere på stigende vannføring sammenliknet med synkende vannføring, for de tre episodene som var undersøkt for bekk A, B og C. Dette kan tyde på at mer organisk materiale tilføres bekken på stigende flom sammenliknet med synkende, ved tilsvarende vannføring, under de undersøkte episodene. Bekk D hadde både de høyeste nivåene av TOC og fargetall, samtidig med lavest bufferevne. For en analysert hendelse med ekstremnedbør var det i denne bekken en meget forlenget periode før pH var tilbake til nivået den lå på før hendelsen. Dette førte til et mer komplekst åttetallsformet hysteresemønster. Kalkingen i innsjøene i nedbørfeltene påvirket bakgrunnsnivået for buffer-parametere og pH, men hindret ikke den vannkjemiske responsen på økt vannføring og flomhendelser. Likevel var motstandsdyktigheten mot de vannkjemiske endringene i bekk A betydelig bedre med tanke på absolutte verdier av de kjemiske parameterne for hele spennet av vannføring. Det ser også ut til at innsjøkalkingen i nedbørfelt B forbedret hastigheten på restitusjonen av pH på synkende vannføring etter flomhendelser. For bekk A var både pH signifikant høyere for hele spennet i vannføring og Ali signifikant lavere i bakgrunnsnivå sammenliknet med de andre bekkene. Verken verdier fra pH-logger eller vannprøver gikk under/over aktuelle grenseverdier brukt i denne studien for bekk A. To av fire bekker viste positive langtidstrender for fargetall, i tillegg til fem av elleve innsjøer i nedbørfeltene og Råsjøen (resipienten). Dette tyder på at browning er relevant i studieområdet og i Råsjøens nedbørfelt. De kraftigste episodiske surstøtene inntraff i bekk D, hvor pH holdt seg under 4 sammenhengende i omtrent to dager, for to forskjellige perioder høsten 2025, og under 4.5 for tilnærmet en uke. Bekk D hadde også de laveste tetthetene for både 0+ og 1+ ørret. Resultatene tyder på at hydrologiske forhold i stor grad styrer vannkjemien i disse boreale bekkene. Innsjøkalking oppstrøms beskytter ikke bekkene direkte mot episodiske surstøt indusert av økt vannføring, men resultatene tyder på at det kan beskytte mot omfanget av pH-fallene i tillegg til restitusjonstid for pH i etterkant av flomhendelser.
Forfattere
Tveter, Celine Sophie DollySammendrag
Mangrove forest is an important ecosystem, as it serves several roles both on a local and global scale. In addition to supporting biodiversity and local communities, mangroves act as major carbon sinks. Accurate estimation of above-ground biomass (AGB) is therefore important for assessing carbon storage and potential carbon emissions. However, field-based biomass estimation is resource intensive and difficult to conduct across large or inaccessible areas, making national-scale estimates challenging. This study aims to develop and compare machine-learning approaches for predicting and estimating mangrove forest above-ground biomass density (AGBD) using Global Ecosystem Dynamics Investigation (GEDI)-derived reference data and multi-sensor satellite predictors for coastal Tanzania. The objectives of this study is to: 1) develop and compare a set of machine-learning regression frameworks for AGBD estimation using robust validation strategies appropriate for spatial data, 2) quantify the performance of all the frameworks and the uncertainty of the best framework, and 3) produce a wall-to-wall map of mangrove AGBD for coastal Tanzania and compute the mean density and total biomass at national and regional level. Twelve frameworks were developed by combining the regression algorithms Random Forest, eXtreme Gradient Boosting, Support Vector Regression, and Ridge with the cross-validation strategies completely random, randomized stratification, and grouped stratification. The best-performing framework was further optimized and used for the final prediction. Random Forest with randomized stratification achieved the best overall performance among the tested frameworks, with test RMSE of 29.3 \si{\mega\gram\per\hectare} and R^2 of 0.36. After optimization, the metrics improved to 27.4 Mgha^-1 and 0.39 for RMSE and R^2, respectively. The final prediction estimated a national mangrove AGB of 4.05 million Mg for 2021, with a 95\% confidence interval of [3.93, 4.17] million Mg, corresponding to an average density of 30.98 Mgha^-1. The results showed the potential of combining multi-sensor remote sensing data and GEDI-derived biomass estimates for large-scale mangrove biomass estimation. However, uncertainties related to the GEDI reference data, signal saturation, and model heteroscedasticity, especially at high densities, should be considered when interpreting the results.
Forfattere
Nordfjellmark, LoviseSammendrag
Human land use change, including agricultural intensification, has resulted in global declines of pollinators, such as bumble bees. Increased agricultural intensification has reduced availability and distribution of floral resources and nesting habitats within landscapes, which may have cascading effects on bumble bee communities. This study explores how flower availability and landscape structure in the highly intensive agricultural landscapes of Southwest Norway affects local bumble bee diversity, abundance, and worker body size. I collected data on local bumble bee abundance and diversity using insect-traps, as well as floral resource abundance during three registrations periods during the summer of 2025. Intertegular distance (ITD) was used as a measure of bumble bee body size, since it is also an indicator of flight muscle volume, and therefore foraging capacity. I found no clear effect of total flower abundance, nor landscape heterogeneity on total bumble bee abundance, or on bumble bee worker body size. However, long foraging species were observed to be the most abundant, which suggests prior selection by the study landscape for species with long foraging range. I also found strong interspecific differences in intertegular distance among species, with Bombus s.str, the most abundant taxa, being significantly larger than the other analyzed species. This suggests that larger body size confers an overall advantage in homogenous landscapes.
Forfattere
Gramstad, LeneSammendrag
Agricultural intensification and other land use changes have had detrimental effects on pollinating insects. As such, identifying measures to slow or reverse their population declines is critical. Sown flower strips are one such mitigating measure. I evaluated the effects of annual and perennial flower strips on communities of bumble bees and butterflies by assessing abundance, richness, visitation rates, and movement of pollinators in Ås, Norway. Flower abundance was recorded through quadrat sampling complemented by site-level observations, while pollinator abundance and richness were recorded through repeated transect walks, during which bumble bees and butterflies were counted and identified, and butterflies were marked and recaptured. Annual flower strips were found to have the highest flower abundance and benefitted both pollinator groups, whereas perennial flower strips primarily benefitted bumble bees and had flower abundances more similar to grass dominated road verges. Bumble bee and butterfly abundances did not decrease with distance from the sown flower strips, suggesting high connectivity between the flower strips and a positive effect of landscape context on pollinator movement. The results suggest that annual flower strips conferred the greatest benefit to pollinators in the study system, and that perennial flower strips require improvements in floral resources to better support pollinator communities.
Forfattere
Lund, ØyvindSammendrag
Coastal vegetation provides important ecosystem services such as carbon sequestration, wildlife habitat, and protection from erosion, and mapping the different vegetation types is vital for their protection. There has been little research on classification and mapping of the coastal vegetation in Western Africa, and especially in Ghana. This study classifies the coastal vegetation of Ghana using both high-resolution UAV imagery and Sentinel-2 imagery and compares three machine learning models for the task: Random Forest, Support Vector Machine and Extreme Gradient Boosting. The classification was done using an Object-Based Image Analysis (OBIA) workflow, where the imagery was segmented, labeled and classified using spectral, textural, and geometric features. The UAV classification was also used as an additional source of training data for the Sentinel-2 classification. XGBoost achieved the highest scores for the UAV classification with a macro F1-score of 0.858, though all three classifiers performed comparably, while SVM performed best for the Sentinel-2 imagery with a macro F1-score of 0.817. The integration of UAV training data worked well for classes that were detectable at 10 m resolution, but the limited spatial coverage of the UAV imagery meant it could not provide enough samples for the smaller classes. The final output is a coast-wide vegetation map of Ghana, where the total mangrove area was estimated at 102.84 km2, which is lower than in previous studies. The main sources of error were the lack of field data, limited spectral and spatial coverage of the UAV imagery, and the broad class definitions. Despite this, the study shows that combining UAV and Sentinel-2 imagery in an OBIA workflow can produce a consistent coast-wide classification of coastal vegetation. It also highlights the need for probability-based area estimation in future work to produce more reliable and comparable area estimates.
Forfattere
Anna Amberntsson Dina Moxness Konglevoll Annika Eliassen Mari Mohn Paulsen Anne Lise Brantsæter Marianne Hope Abel Lene Frost AndersenSammendrag
Abstract Purpose: Alternatives to animal-sourced foods (Alt-ASFs) are processed plant-based products that mimic animal-sourced foods. This study aimed to describe the consumption of Alt-ASFs in the Norwegian dietary survey (Norkost 4) and compare population characteristics and nutritional intake in regular consumers. Further, to compare the nutritional quality of Alt-ASFs consumed and describe the distribution of the Nutri-Score and NewTools-score - a proposed revised version of Nutri-Score, among these products. Methods: Dietary data were collected from 1,815 adults in Norkost 4 using 2*24-h recalls and a food frequency questionnaire. Alt-ASFs were identified and compared with corresponding ASFs. Nutritional quality was assessed and products were scored using Nutri-Score and NewTools-score. Results: Overall, the consumption of Alt-ASF was low (mean: 0.3 energy %, SD: 1.6). 8% ( n = 147) reported consuming one or more Alt-ASFs regularly, defined as ≥ 2 times/week, with dairy alternatives being most frequently consumed. Regular consumers were typically younger, female, and more likely to report a vegetarian diet. Most Alt-ASFs contained lower levels of the assessed micronutrients except for meat and fortified milk, whose micronutrient content was similar or higher than ASFs. There was a wide variation in nutritional scores for Alt-ASFs. Unfortified Alt-ASFs typically had a low micronutrient content but could still achieve favourable Nutri-Scores if low in salt, sugar and saturated fat. Conclusion: Our findings indicate that only a minor part of Norwegian adults regularly consumes Alt-ASFs and consumption is low. Shifting from ASFs to Alt-ASFs may have some nutritional benefits and some disadvantages, largely dependent on the chosen products.
Sammendrag
Abstract Algal cultures are widely used to study algae–bacteria interactions, yet the relative roles of algal taxonomy, culturing environment, and historical contingency in shaping bacterial communities of long-maintained monoalgal cultures remain unclear. In a two-stage experimental design, we used 16 S rRNA metabarcoding to first profile the bacterial communities of 14 filamentous freshwater algal strains from three orders (Chaetophorales, Oedogoniales, Zygnematales) maintained in two distinct culture collections, and then, in a second experiment to test community mixing using a co-culture and re-isolation design with two algal strains ( Stigeoclonium sp. and Oedogonium sp.). The 14-strain profiling showed that bacterial communities were broadly similar at higher taxonomic ranks, with many shared orders within Pseudomonadota, whereas composition at the ASV level was largely algal-strain-specific. Ordination of phylogeny-aware UniFrac distances showed that culture collection of origin explained more variation in community composition than algal order, an effect reduced but not eliminated after standardizing the culture medium. The co-culture and re-isolation experiment showed that the two algal strains exchanged many bacterial community members, yet algal strain identity remained detectable after re-isolation. These results support a framework where culture history results in strain-specific ASV-level composition within recurrent higher-rank structure, and where algal-strain-specific effects on bacterial community composition become evident when cultures are exposed to a shared bacterial pool. Co-culture followed by algal re-isolation offers a practical approach to examine the persistence of algal-culture bacterial communities under mixing and may help identify candidate bacterial partners with potentially strong host-specific interactions without requiring axenic hosts.
Sammendrag
Abstract Single-date UAV vegetation indices are widely used to assess potato crop performance and estimate yield. However, whether their biological interpretation remains consistent across cultivars and growth stages is rarely examined. This study investigated how the relationships between UAV-derived multispectral and thermal canopy indicators and potato yield changed during crop development under contrasting irrigation in two cultivars with contrasting maturity classes (Anouk and Celandine). UAV surveys were conducted in July and August, and canopy metrics were related to final yield and tuber traits. The relationship between NDVI and yield differed markedly between cultivars and growth stages. In the early-maturing cultivar Anouk, July NDVI showed a strong positive correlation with yield ( r = 0.87, p = 0.002), whereas August NDVI was not informative. In the late-maturing cultivar Celandine, the relationship reversed from a positive correlation in July ( r = 0.56) to a strong negative correlation in August ( r = −0.80, p = 0.009), indicating that greater late-season canopy greenness was associated with lower yield. Exploratory LOOCV Random Forest models achieved the highest yield prediction accuracy using July features for Anouk ( R 2 = 0.72) and August features for Celandine ( R 2 = 0.47), while multi-temporal features provided similar predictive performance. Greater temporal declines in NDVI were associated with higher yield in both cultivars, consistent with the change in canopy greenness acting as a phenological indicator of the transition from vegetative growth to tuber bulking. These results demonstrate that the interpretation of UAV-derived vegetation indices is strongly dependent on cultivar maturity and growth stage. A single UAV acquisition may therefore provide misleading assessments of crop performance when canopy phenology is not considered. Rather than serving as fixed proxies for yield, canopy vegetation indices should be interpreted within cultivar-specific and temporal contexts when used for potato monitoring and agronomic decision-making.