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.
2024
Authors
Helle Ross Gobakken Mostafa Hoseini Stephan Hoffmann Jan Bjerketvedt Johannes Rahlf Rasmus AstrupAbstract
No abstract has been registered
Abstract
Point clouds from laser scanning are a standard data source in forest research, but the lack of clear and robust workflows has limited the translation of experimental knowledge into operational tools. We present a novel machine learning-based workflow that uses individual-tree point clouds from drone laser scanning to predict wood quality parameters. Unlike object reconstruction methods, our approach is based on simple metrics computed on vertical slices that summarize information of point distances, angles, and geometric attributes of the empty space between and around the points. Our models use these slice metrics as predictors and achieve high accuracy for predicting diameter of the largest branch per whorl (DLBw) and stem diameter at different heights (DSi) from survey-grade drone laser scans. We show that our models are also robust and accurate when tested on suboptimal versions of the data generated by reductions in the number of points or emulations of suboptimal segmentation scenarios. Our approach provides a simple, clear, and scalable solution that can be adapted to different situations and has the potential to revolutionize forest management and monitoring
Abstract
Climate change poses significant challenges to forests, increasing the occurrence and severity of disturbances such as windthrows, wildfires, pests, and diseases. Effective decision-making tools are crucial for mitigating forest damages and enhancing resilience under changing climatic conditions. We explore the role of forest decision support systems (DSS) in addressing these challenges and present their potential in mitigating future climate-induced damages to forests. We examine the key challenges associated with integrating disturbances and their interactions into decision support systems, using as motivating example the decision support systems for the high-resolution Norwegian forest resources map SR16.
Authors
Mats Hoem OlsenAbstract
This comparative study examines the efficacy of three established models for predicting soil temperatures at depths of 10cm and 20cm across four Norwegian regions: Innlandet, Østfold, Vestfold, and Trøndelag. To ensure comprehensive regional representation, four monitoring stations were strategically placed within each region. Utilizing data from \acrshort{ac:nibio}, including hourly air temperature at 2m and soil temperatures at 10cm and 20cm depths, the study evaluated seven models cited in existing literature. These models included Linear Regression, Plauborg’s Linear Regression for daily and hourly values, LSTM, bidirectional LSTM, GRU, and bidirectional GRU. The findings revealed improved performance of bidirectional models over unidirectional ones and comparable results between the hourly extension and Plauborg’s original daily model. Notably, deep learning models exhibited a dual-mode operation to adapt to the transitional Autumn/Spring and stable Summer periods. It was found that the bidirectional models performed the best and that bidirectional LSTM worked best for 10 cm soil temperature while Bidirectional GRu worked best for 20 cm soil temperature. It was also found that the inclusion of time in regression models improved the models predictive capabilities. The author of this current study advocates for further research into bidirectional models and suggests broadening the feature set beyond two variables to capture additional predictive variations.
Authors
Kari Straume EnerstadAbstract
The climate is changing, and people and goods are crossing country borders more than ever. As a result, the number of alien plant species have increased worldwide, and it does not seem to be slowing down. This makes it even more important to find effective and sustainable management approaches to preserve the native species and habitats from the challenges invasive alien species may bring. This thesis explores the topic of alien plant species in the cultural landscape and how climate change and globalization impact the spread and establishment of these plants. The aim of the thesis is to identify the impacts climate change and globalization have on alien species and learn how they are managed. Additionally, investigate if discovered, alternative approaches could be applicable to the Norwegian management approaches on various levels of government. The thesis investigates how Norway manages alien plant species and explores the roles of national, regional and local government through theory and interviews. Three other nations are also studied, England, South Africa and Canada, to create a greater understanding of the variations in management and to compare the different approaches. The study found large variations in the municipal management approaches, limited collaboration between the stakeholders and decreased funding. A lack of knowledge and awareness among the public was also discovered. These factors collectively make managing alien plants difficult. Enhancing collaboration among national, regional and local management levels, alongside strengthening public awareness, has the potential to increase resources and enhance the effectiveness of management strategies.
Authors
Ingvild Alseth MolandAbstract
This thesis explores an urbanized area in Norway, which is an important area for migratory birds both nationally and globally, through a case analysis. Together with knowledge base, the case analysis is used to develop some important measures for wader bird friendly urban landscapes. Urbanization and downsizing of nature put biodiversity under pressure, and many species are fighting for their survival. Bird populations are declining worldwide, and the species that are mostly affected by urbanization are often the species with special habitat requirements. In Europe, ground nesting birds experience a larger decline compared to other bird species. Wader birds are in rapid population decline and are therefore of conservation concern across Europe. Globally there are about 209 species of wader birds, and in Norway there are around 70 species registered. Population decline has been observed in several species of waders, and about 50 % of the waders in Norway are appearing on the Norwegian red list for species. Management decisions have the potential to influence important nesting and feeding habitats and protect wader birds in urban areas. Still, the wader birds have received a limited amount of attention and research in Norway. Fornebu, in Bærum municipality, is characterized as one of the most species rich localisations in Norway. Fornebu has gone through dramatic land use changes, transforming from an initial farming area to the primary airport of Norway, to a large housing project for business, housing, and recreation. The housing project is Northern Europe’s largest housing project and has affected the nature values through the construction of roads, housing, park-like landscapes, and increased human disturbance. The transformation has changed the natural landscape leading to a reduction of bird habitats. A document analysis reveals the municipality’s plans for future development of the landscape, and stakeholders’ perspectives on facilitating the landscape, through measures that might affect wader birds. The measures that emerge as most important is: to preserve the shoreline, restore wetlands, establish ponds, take care of meadows, facilitate edges with native vegetation, establish suitable habitats on green roofs, facilitate paths and signs for education amongst people, and facilitate protection against predators. The measures can help to protect and enhance the abundance of wader birds in urbanization processes and already urbanized landscapes and can help to raise awareness and promote education to citizens. The measures will also affect other species and can enhance the overall resilience of an urban environment.
Authors
Sigrid Esmeralda ArnestadAbstract
På norske gravplasser er plassmangel et problem grunnet svært treg nedbrytning av menneskekropper som fremdeles kan være intakte etter flere tiår i en kistegrav. Ved etablering av nye gravfelt har masseutskifting med blandinger av maskinelt knust sand blitt benyttet for å sikre god drenering. Det eksisterer derimot lite kunnskap om langtidseffekten av denne type kunstig jord på nedbrytning i kistegraver. Knust sand fra stein har troligere høy pH og skarpere overflater som sannsynligvis pakkes annerledes enn naturlig rundet sand, hvilket kan ha betydning for jordfysiske egenskaper og påvirke transport og innhold av vann og luft. De antatte egenskapene kan påvirke forhold som styrer den mikrobielle aktiviteten, som er avgjørende for god nedbrytning. Oppgaven har derfor som formål å bidra til økt kunnskap om egenskaper til knust sand gjennom å karakterisere fysiske, hydrauliske og kjemiske egenskaper, samt å undersøke jordmassenes påvirkning på organisk mikrobiell nedbrytning. Ulike tester ble gjennomført i et lysimeteranlegg på følgende utvalg av sand; to typer knust sand, to naturlige sand, og fire typer blandinger av disse. Teposer ble begravd i to dybder med kontrollert vannstand og standard fysiske og kjemiske analyser samt vannlagringskapasitet ble undersøkt på jordprøver i lab. I tillegg ble infiltrasjonshastighet målt på jordmassene i lysimetrene. Resultatene fra studiet viste at massetap av te var signifikant mindre i knust enn naturlig sand, forholdsvis i det øvre jordlaget. Det antas at dette i hovedsak skyldes redusert mikrobiell nedbrytning, trolig som følge av høyere pH, lavt innhold av organisk materiale og for lite fuktighet i de knuste massene. Sistnevnte antakelig på grunn av lav vannlagringskapasitet. Nedbrytning av te var generelt lavere i det nedre jordlaget, trolig grunnet redusert oksygen som følge av mer fuktighet fra den nærliggende vannstanden. I de groveste kunstige og naturlige sandtypene ble det derimot ikke observert redusert nedbrytning i det nedre jordlaget, mulig som følge av fravær av kapillært vann fra den nærliggende vannstanden og antakelig fremdeles opprettholdelse av aerob mikrobiell aktivitet. Samtidig bør det bemerkes at forskjellene i nedbrytning stort sett ikke var signifikante mellom noen av jordtypene i dette jordlaget. Sandpartiklene ser ut til å være betraktelig mer kantet enn de naturlige, men studien viste ingen overbevisende forskjell i total porøsitet og det er behov for mer forskning på langtidseffekten av konsolidering som følge av forskjeller i partikkelform. I alt indikerer resultatene at mikrobiell nedbrytning kan begrenses i knust sand sammenliknet med naturlig, noe som vil være ugunstig dersom massene benyttes på kirkegårder der det er ønske om høy mikrobiell aktivitet og nedbrytning.
Authors
Hanna Marie KjernsbyAbstract
Finansiert av Statens Vegvesen
Authors
Elias GarvikAbstract
The Norse built their hulls from oak boards hewn from cleaved or ‘rived’ logs. We know this through artworks and texts as well as archaeological finds describing the ships as well as their construction from the latter half of the early-medieval period. However, we know summarily little when it comes to the pre-production of hewn boards. I ask, - How could the Norse have possibly cleaved? - Which properties in white oak affect cleaving? - Which simple truths can be found of cleaving. Which direction of cleaving is best for oak? This is done by showcasing the differences in cleaving from the top, side, and bottom of a series of white oak logs. Namely why cleaving from each direction fails. To summarize the results. Cleaving from the top shines in cases where there is a large difference in the diameter at the top and bottom of the log. Cleaving from the side can act as a mitigator in the case of knots or to pierce directly through a knot or burl. Cleaving from the top or bottom falls more naturally in the cases where the pith is off-centre. With a log bent like an arch, cleaving from the side fell more naturally. The direction of the cleave ought to be thought of less as an immutable truth and more of as another tool to extract as many boards from a log as possible. We found that no direction of cleaving was inherently better in all scenarios. It is a case of risk-mitigation, which benefits from taking a thorough look at the log and making an informed choice. In cases where the angle of the twisting fibres of a log is significant, all cleaving directions struggle and fail, in cases where there are few natural faults, cleaving from all sides succeed.
Authors
Einar Lyche LebesbyeAbstract
Land-based wind power is considered one of the most applicable sources of renewable energy for the future. While cost effective, the knowledge of ecological consequences associated with construction and operation is limited. This thesis investigates how vegetation and cervid animals at Lista Wind Park were affected by its construction and operation. Vegetation data in revegetated and control plots were compared over a twelve-year period and tested for variation in species richness, species diversity and foliar coverage. Dispersal of alien species, as a result of infrastructure construction, was also investigated. Cervid habitat use was mapped one year before, during construction and several different years after the wind park was set into operation. This data was considered unreliable due to inconsistency in sampling circumstances and lack of calibration between observers, and not analysed further. Rather, inter-observer discrepancies in species identification were investigated. Vegetation in revegetated plots seems to converge towards control plots after twelve years. Differences in species richness, species diversity and foliar cover are no longer significant. However, models fail to account possible variations due to climate. The construction of the wind park resulted in dispersal of alien species. In general, experienced observers had trouble identifying species though photographs of feces, only being certain in ca. 50% of the cases. In cases where observers were certain, species ID was different compared to another observer in 19% of the cases. More studies are needed to determine land-based wind powers ecological consequences, especially on cervids.