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
Tilde Hjermann Nikolai Antonsen Bilet Inger Maren Rivrud Erling Meisingset Pål Thorvaldsen Atle MysterudAbstract
Grazing by wildlife on agricultural land is widespread across geographical regions, and can cause human–wildlife conflicts due to reduced crop yield when the grazing pressure is high. Growing red deer (Cervus elaphus) populations in Europe call for an increased understanding of their grazing patterns to mitigate damages. We quantified how red deer grazing pressure (grazing presence and grazing level) on agricultural grass meadows (n = 60) in Norway varied across multiple spatial scales. We used a nested, hierarchical study design transcending from a broad scale (meadows across the landscape) to intermediate (between nearby meadows) and local (within-meadow) scales, allowing us to identify at which scale the variation in grazing pressure was strongest. We estimated how grazing was determined by broad-scale factors influencing forage availability and quality through population density, distance to coastline, and differences between the first versus second harvest, by intermediate-scale factors in terms of meadow management causing differences in botanical composition and quality, and by local-scale factors in terms of perceived predation risk and disturbance. At a broad scale, higher population densities were associated with higher grazing pressure, and more grazing occurred before the first compared to the second harvest. Intermediate-scale factors explained the most variation of grazing pressure from red deer, with higher grazing pressure on newly renewed meadows compared to other nearby meadows. On a local scale, more grazing occurred closer to the forest edge, providing cover, and further away from infrastructure, with increased risk and disturbance. Overall, our study highlights how drivers of grazing pressure on agricultural land vary across spatial scales. Population reductions on a broader scale may have some effect in reducing the grazing pressure, but renewed meadows will nevertheless attract red deer, causing higher grazing pressure compared to neighbouring meadows. This insight is crucial for determining effective mitigation strategies facing rising red deer populations across Europe.
Authors
Tilde K. S. HjermannAbstract
Agriculture has significantly impacted the land use over the past centuries. For wild herbivores such as the red deer, foraging on farmland can be beneficial when food is limited in their natural habitats. In Norway, the red deer populations consist of migratory and resident individuals, where migrants travel from low-elevation winter ranges, typically with more available farmland, towards higher-elevation summer ranges. Residents remain in the low-elevation areas year-round. I found that residents selected farmland more than migrants, buffering the migrants’ benefit from following the wave of emerging vegetation in spring. Higher farmland availability also delayed the red deer’s spring migration, that generally varied greatly between and within years. Wildlife foraging on farmland can cause conflicts with humans due to reduced crop yield. Grazing can vary with factors on different scales, and I found most variation in grazing between neighbouring meadows, with more grazing on those recently renewed. Within meadows, more grazing was found close to the forest and away from infrastructure. On broad scale, grazing increased with population density. My thesis provides insight into the coupled dynamics of the red deer and agricultural farmlands, which can be important for management of this coupled ecosystem.
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Authors
Ilona Knollová Milan Chytrý Helge Bruelheide Stefan Dullinger Jutta Kapfer Franz Essl John-Arvid Grytnes Vigdis VandvikAbstract
No abstract has been registered
Authors
Sara A Meier Melanie Furrer Nora Nowak Renato Zenobi Monica Alterskjær Sundset Reto Huber Steven A. Brown Gabriela WagnerAbstract
Reindeer in the Arctic seasonally suppress daily circadian patterns of behavior present in most animals. In humans and mice, even when all daily behavioral and environmental influences are artificially suppressed, robust endogenous rhythms of metabolism governed by the circadian clock persist and are essential to health. Disrupted rhythms foster metabolic disorders and weight gain. To understand circadian metabolic organization in reindeer, we performed behavioral measurements and untargeted metabolomics from blood plasma samples taken from Eurasian tundra reindeer (Rangifer tarandus tarandus) across 24 h at 2-h intervals in four seasons. Our study confirmed the absence of circadian rhythms of behavior under constant darkness in the Arctic winter and constant daylight in the Arctic summer, as reported by others.1 We detected and measured the intensity of 893 metabolic features in all plasma samples using untargeted ultra-high-performance liquid chromatography-mass spectrometry (UPLC-MS). A core group of metabolites (66/893 metabolic features) consistently displayed 24-h rhythmicity. Most metabolites displayed a robust 24-h rhythm in winter and spring but were arrhythmic in summer and fall. Half of all measured metabolites displayed ultradian sleep-wake dependence in summer. Irrespective of the arrhythmic behavior, metabolism is rhythmic (24 h) in seasons of low food availability, potentially favoring energy efficiency. In seasons of food abundance, 24-h rhythmicity in metabolism is drastically reduced, again irrespective of behavioral rhythms, potentially fostering weight gain.
2023
Authors
Madelen Cecilia Espino FjeldAbstract
Et essensielt tema innen økologi er at oppfostring av avkom hos mange arter krever tilgang på betydelige ressurser og at fødselstidspunktet synkroniseres for å treffe toppen til ressurstilgangen i sesongmessige miljøer. Dagens raske klimaendringer mot for eksempel høyere temperaturer og en tidligere vår i nordlige økosystemer, har ført til at mange planter har vist trender for tidligere fenologiutvikling. For plantespisende pattedyr kan dette føre til trofisk «mismatch» mellom tidspunkt for fødsel og den fenologiske utviklingen hos beiteplantene, og vil kunne føre til at fødselstidspunktet ikke lenger treffer tidspunktet med optimal tilgang på ressurser. Endring i de klimatiske faktorene kan føre til seleksjon for tidligere eller senere fødselstidspunkt. For hjortedyr har tidspunkt for brunst og parring påvirkning på kalvingstidspunktet, og en høyere bestandstetthet hos enkelte arter kan føre til senere unnfangelse. Få tidligere undersøkelser har dokumentert om kalvingstidspunktet til hjortedyr er blitt endret over tid. En av årsakene til dette er mangel på data, siden det er vanskelig å observere kalving og kalvingstidspunkt i skogsområder. På grunn av en endret atferd til hjortedyr under kalving, er det hos enkelte arter vist at det er mulig å sannsynliggjøre oppdagelse av kalving ved bruk av ny teknologi (posisjonsdata fra GPS-halsbånd). Målet for dette prosjektet var å undersøke om posisjonsdata kan brukes til å påvise kalving og kalvingstidspunkt hos hjort (Cervus elaphus), og deretter bruke metoden for å undersøke om kalvingstidspunktet har endret seg over tid og med bestandstetthet i Norge. I analysene ble det brukt GPS-data fra 188 hjort og 309 mulige kalvingshendelser fra perioden 2005-2021 fra Trøndelag og Møre og Romsdal i Norge. Tjue koller med observert kalvingstidspunkt ble brukt som utgangspunkt for endringspunktanalyse og maskinlæring, for å finne estimert kalvingstidspunkt og -status ved hjelp av kovariater knyttet til bevegelsesmønster. Observert og estimert kalvingsstatus ble sammenlignet, men det var kun 81% av kollene som ble riktig estimert, som var et svakere resultat enn forventet. Når metoden ble brukt på et større utvalg av hjort, var det ikke mulig å påvise klare trender i kalvingstidspunkt over tid, men dette kan skyldes svakheter med metoden. Hjorten er en art som har en gjemmer-strategi første uken etter kalving. Den intensive perioden rett etter kalving er kort for en gjemmer som fører til utfordringer ved deteksjon av kalvingshendelser, og maskinlæringsmetodene bør derfor utvikles ytterligere for å få sikrere resultater. Dette vil være et viktig tema med tanke på hvordan klimaendringer kan påvirke det fremtidige økologiske samspillet.
Authors
Nikolai Antonsen BiletAbstract
The size of the Norwegian red deer population is historically high and typical of the trend seen over much of Europe. Dense populations may cause damage to agricultural crops, and crop yield is drastically decreased by red deer grazing in certain areas. We know that red deer select actively managed meadows, i.e., frequently renewed by fertilisation and re-seeding, over other agricultural meadows. Despite its importance, information regarding spatial grazing patterns by red deer on agricultural meadows is limited. In this study, I aim to quantify how grazing on agricultural meadows by red deer varies across spatial scales in southwest Norway. I hypothesise that grazing on agricultural meadows is determined by three major effects: (H1) Factors affecting forage quality and availability in meadows relative to natural habitats, such as population density and seasonal change, (H2) meadow management, such as renewal of meadows, and (H3) perceived predation risk and human disturbance, such as distance to settlement and forest edge. Grazing levels were assessed across meadows in a hierarchical study design, and I analysed the data using a binary logistic regression that model absence of grazing and a beta regression that model the level of grazing given grazing occurred. This enabled me to quantify both variation among spatial hierarchical units and the mechanisms behind spatial grazing patterns. I found that the grazing variation was largest between meadows in the local area and smallest on broader scale. High red deer density areas received more grazing relative to low-density areas, more grazing occured when meadow grass was shorter, and early in summer relative to late, suggesting that red deer select meadows over natural habitat when the difference in quality and availability of forage are large enough. Newly refreshed meadows received more grazing than the older ones, implying that a large part of the local site effect was caused by meadow management. Evidence of trade-off effects also appeared important as spatial grazing patterns changed near roads, houses, and forests. Broad-scale variation in red deer density explained some of the variations in grazing. However, since the largest variation in grazing was found locally, population reduction at broad scales may not effectively lower damages. These results may affect the scale at which management should target mitigation efforts.
Authors
Lise GrøvaAbstract
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