Airborne laser scanning reveals increased growth and complexity of boreal forest canopies across a network of ungulate exclosures in Norway

Large herbivores are often classed as ecosystem engineers, and when they become scarce or overabundant, this can alter ecosystem states and influence climate forcing potentials. This realization has spurred a call to integrate large herbivores in earth system models. However, we lack a good understanding of their net effects on climate forcing, including carbon and energy exchange. A possible solution to this lies in harmonizing data across the myriad of large herbivore exclosure experiments around the world. This is challenging due to differences in experimental designs and field protocols. We used airborne laser scanning (ALS) to describe the effect of herbivore removal across 43 young boreal forest stands in Norway and found that exclusion caused the canopy height to increase from 1.7 0.2 to 2.5 0.2 m (means SE), and also causing a marked increase in vertical complexity and above-ground biomass. We then go on to discuss some of the issues with using ALS; we propose ALS as an approach for studying the effects of multiple large herbivore exclosure experiments simultaneously, and producing area-based estimates on canopy structure and forest biomass in a cheap, efficient, standardized and reproducible way. We suggest that this is a vital next step towards generating biome-wide predictions for the effects of large herbivores on forest ecosystem structure which can both inform both local management goals and earth system models biomass, herbivory, large herbivores, LiDAR, moose, remote sensingpublishedVersio

Airborne laser scanning reveals uniform responses of forest structure to moose (Alces alces) across the boreal forest biome

1. The moose Alces alces is the largest herbivore in the boreal forest biome, where it can have dramatic impacts on ecosystem structure and dynamics. Despite the importance of the boreal forest biome in global carbon cycling, the impacts of moose have only been studied in disparate regional exclosure experiments, leading to calls for common analyses across a biome-wide network of moose exclosures. 2. In this study, we use airborne laser scanning (ALS) to analyse forest canopy re-sponses to moose across 100 paired exclosure-control experimental plots dis-tributed across the boreal biome, including sites in the United States (Isle Royale), Canada (Quebec, Newfoundland), Norway, Sweden and Finland. 3. We test the hypotheses that canopy height, vertical complexity and above- ground biomass (AGB) are all reduced by moose and that the impacts vary with moose density, productivity, temperature and pulse disturbances such as logging and insect outbreaks. 4. We find a surprising convergence in forest canopy response to moose. Moose had negative impacts on canopy height, complexity and AGB as expected. The responses of canopy complexity and AGB were consistent across regions and did not vary along environmental gradients. The difference in canopy height be-tween exclosures and open plots was on average 6 cm per year since the start of exclosure treatment (±2.1 SD). This rate increased with temperature, but only when moose density was high. 5. The difference in AGB between moose exclosures and open plots was 0.306 Mg ha−1 year−1 (±0.079). In browsed plots, stand AGB was 32% of that in the exclosures, a difference of 2.09 Mg ha−1. The uniform response allows scaling of the estimate to a biome-wide impact of moose of the loss of 448 (±115) Tg per year, or 224 Tg of carbon. 6. Synthesis: Analysis of ALS data from distributed exclosure experiments identified a largely uniform response of forest canopies to moose across regions, facilitat-ing scaling of moose impacts across the whole biome. This is an important step towards incorporating the effect of the largest boreal herbivore on the carbon cycling of one of the world's largest terrestrial biomes.publishedVersio

Seleksjon i reketrål: overlevelse til reker som selekteres ut i overflaten - Sluttrapport for FHF-prosjekt 901661

Fra 2020 til 2022 ble det gjennomført en rekke forsøk i Skagerrak i forbindelse med seleksjon og overlevelse til dypvannsreker (Pandalus borealis). Hovedmålsettingen var å kvantifisere hvor stor andel av trålsekkseleksjonen av reker som skjer i havoverflaten og undersøke overlevelsen til rekene som selekteres ut her. Overlevelsen til reker som unnslipper i overflaten avhenger av miljøforholdene i overflaten og hvor lenge de eksponeres for disse. Høy dødelighet på utsortert småreke vil være en alvorlig feilkilde i bestandsberegninger og også reduserer utbyttet fra bestanden. Forsøkene ble inndelt i fire arbeidspakker: Kvantifisering av seleksjon i havoverflate og på bunn, adferds- og toleranseundersøkelser, metodeutvikling for overlevelsesforsøk i felt og overlevelsesforsøk i rekefiske (feltforsøk).Seleksjon i reketrål: overlevelse til reker som selekteres ut i overflaten - Sluttrapport for FHF-prosjekt 901661publishedVersio

Location of studies and evidence of effects of herbivory on Arctic vegetation: a systematic map

Herbivores modify the structure and function of tundra ecosystems. Understanding their impacts is necessary to assess the responses of these ecosystems to ongoing environmental changes. However, the effects of herbivores on plants and ecosystem structure and function vary across the Arctic. Strong spatial variation in herbivore effects implies that the results of individual studies on herbivory depend on local conditions, i.e., their ecological context. An important first step in assessing whether generalizable conclusions can be produced is to identify the existing studies and assess how well they cover the underlying environmental conditions across the Arctic. This systematic map aims to identify the ecological contexts in which herbivore impacts on vegetation have been studied in the Arctic. Specifically, the primary question of the systematic map was: “What evidence exists on the effects of herbivores on Arctic vegetation?”

Evaluation of floor vibration properties using measurements and calculations

Timber floor constructions are very common in the Nordic countries, for instance in single- and multifamily buildings. But building with wood is increasing in popularity for other building categories and there is wider interest in increasing the span width of wooden joist floors. Static and vibrational performance become crucial for serviceability of timber floors and often limit the design; however, constructors and designers want to increase the floor span width. To meet these challenges, reliable design methods are required and have therefore become a focus in many countries. This paper presents results from a number of measurements of different joist floor constructions. Parameters measured have also been calculated according to given equations and relevant methods. Both calculations and measurements include 17 laboratory objects and four field objects. The objects represent a huge variety of solutions and therefore a large spread of results. The main reason for the selection of floor solutions was to expand the possibilities and test the methods more than tuning current solutions into satisfactory floor vibration perception. The data and resulting analysis in this paper highlight benefits and limitations concerning relevant parameters for evaluation of floor vibration perception. According to this work, it is not possible to verify the Eurocode method with respect to accuracy, and the link to perception of floor vibrations is rather low. Another method should be used or developed for the future. Results presented in this paper show that sufficient accuracy may be achieved using parameters from the Hu and Chui (2004) method. Experiences from Norway over the last five years are also promising regarding evaluation of floor vibration perception using this method. However, attention should be given to floors with significantly lower damping properties and/or significantly higher (modal) masses. Damping properties or an alternative parameter taking a longer time interval of the vibrations into account should be considered.acceptedVersio

Semantically Enriched Recommender Systems for Smart Closets

With increasingly low prices on clothes and a tremendous interest in fashion, results in that people's wardrobes keep piling up. This causes people to struggle with daily selection of an outfit that includes clothing items that are matching and that suits the day's weather. Moreover, the environmental sustainability could benefit from people recycling their textile waste. This thesis investigates how exploiting new technologies, such as Big Data, recommender systems, semantic web, and Internet of Things can guide people in organizing their wardrobes more efficiently. The thesis proposes the architecture of a system consisting of a smart closet where the usage history of the user's clothing items can be tracked using RFID technology. Through a mobile application, the user can view wardrobe inventory, and receive daily outfit recommendations and recommendations for clothing items to recycle. To generate the daily outfit recommendations, the thesis proposes an approach based on collaborative filtering enabled with a machine learning algorithm--carefully selected through an experiment comparing multiple models on a real-world dataset. In addition to daily outfit recommendations, the approach facilitates the possibility of targeted advertisement by clothing retailers. Moreover, the thesis proposes a traditional content-based approach for recycling recommendations. The content-based approach utilizes semantic web technology and results from an evaluation shows that it outperforms a baseline approach without semantic web technology. As a whole, the thesis includes the state of the art for recommender systems utilizing semantic web technology, with especially focus on the domain of fashion recommendation from people's physical wardrobes

Soil charcoal addition affected biochemistry but not growth in European beech and Norway spruce seedlings

Climate change is projected to result in European beech (Fagus sylvatica) expanding northwards into Norway spruce (Picea abies) forests where, in addition to climate, numerous local factors will determine the relative success of these two species. Among these are soil related factors, including charcoal from previous forest fires, which is present in soils in considerable amounts and exerts largely unknown and species-specific effects on plant growth and metabolism. Here I show that glasshouse grown beech and spruce seedlings responded differently to laboratory-produced charcoal addition and that the effect was dependent on plant organ, charcoal origin (beech- or spruce wood), and soil type (beech- or spruce forest). Charcoal addition had no effect on plant biomass, but caused several compound specific changes to the concentrations of low molecular weight phenolics assumed important in plant defences. Shoot:root ratios, specific leaf area, condensed tannin concentrations, and C:N ratios were also affected, but in such a way that the overall positive versus negative effect of charcoal addition could not easily be determined. This was largely due to the organ specific responses that complicates interpretations of the whole-plant response. Overall, the effects of charcoal addition fades in comparison to the effect imposed by soil origin. Results further indicate an uncoupling between growth and phenolic synthesis, contrary to predictions from the protein competition model. The common consensus that soil charcoal has unequivocally beneficial effects on plant growth is challenged. Sammendrag Klimaendringene er sagt å føre til at bøk (Fagus sylvatica) sprer seg nordover inn i områder med granskog, hvor i tillegg til klima, flere lokale faktorer vil påvirke dominansforholdet mellom gran (Picea abies) og bøk. Blant disse er flere jord-aspekter, bl.a. effekten av trekull fra tidligere skogbranner. Trekull finnes i jorda, ofte i betydelige mengder, hvor det har en stort sett ukjent og artsspesifikk effekt på plantevekst og -metabolisme. Her viser jeg hvordan drivhusdyrkede småplanter av gran og bøk reagerte ulikt på tilsetning av laboratorieprodusert trekull til vekstjorda og at effekten av kullbehandlingen var avhengig av opphavet til jorda (bøk- eller granskog) og trekullet (bøk- eller granved), i tillegg til at den ofte var ulik for forskjellige plantedeler. Trekull hadde ingen påvirkning på vekst (biomasse), men induserte flere endringer i konsentrasjonene av ulike lav-molekylvekt-fenoler som man antar er viktige i det kjemiske forsvaret hos planter. Tilsetning av trekull påvirket også skudd:rot forholdet, SLA (bladareal/tørrvekt), konsentrasjonen av kondenserte tanniner, samt karbon:nitrogen forholdet, men pga. kontrasterende resultater i de ulike plantedelene er det vanskelig å fastslå om den totale effekten var overveiende positiv eller negativ. Effekten av trekulltilsetning var veldig liten sammenlignet med påvirkningen av jordtype. Resultatene indikerer videre at det ikke eksisterer en enten-eller dynamikk mellom vekst og fenolsyntese, i strid med prediksjonene fra proteinkonkurransemodellen (en: protein competition model). Den rådende tanken om at trekull har en utelukkende positiv effekt på planter blir herved utfordret

Moose browsing effects on boreal production forests – implications for ecosystems and human society

Sammendrag: Den viktige elgen Utmarkbeite er trolig den mest utbredte arealbruken i Norge, som i verden forøvrig. Etter at mengden beitende husdyr begynte å ned på midten av forrige århundre har ville hjortedyr tatt over deres plass i naturen. Disse ville populasjonene reguleres tett og forvaltes faktisk av landbruks- og matdepartementet. Så på mange måter kan man si at elgen er den nye kua. Hva betyr så elgen for oss? For naturen rundt oss? For samfunnet? Vi snakker om verdens største hjortedyr, en spisemaskin som kan omsette så mye som 40 kg plantemateriale om dagen. I Norge er det rekordmange elg om dagen – ofte 2 dyr per kvadratkilometer flere steder. Dette tilsier at elgen kan ha virkelig mye å si for skogen der den bor, og skal vi nå bærekraftsmålene til FN, og skal vi klare å reversere klimaendringene, ja da kan vi faktisk ikke la være å tenke på elgen. Mitt doktorgradsarbeid har bekreftet at dagens beitetrykk fra elgen går hardt utover løvtrærne som den lever av. Men at det i hele studieområdet vårt ikke skulle finnes en eneste rogn som hadde unnsluppet elgens kjever, det var allikevel dystert nytt. I hvert fall for oss som ønsker å se løvtrær og artsmangfold i skogene. Jeg har også studert hvordan endringene forplanter seg i jordsmonnet og i undervegetasjonen. Ja elgen er viktig for hele økosystemet. Men elgen er også en del av mangfoldet. Og den er jakt, den er kultur og den er tradisjon. Så hvordan veier vi opp alle disse positive og negative sidene ved elg? Avhandlingen min rundes av med oppstarten på noe nytt – ett nettbasert samarbeids og -læringsverktøy for å forstå elgens mange roller i naturen og i samfunnet. Gjennom tverrfaglig samarbeid og med tettere kontakt mellom forskere og samfunnet for øvrig, legger vi grunnlaget for å mer bærekraftig fremtid