Thermal imaging on simulated faults during frictional sliding

Heating during frictional sliding is a major component of the energy budget of earthquakes and represents a potential weakening mechanism. It is therefore important to investigate how heat dissipates during sliding on simulated faults. We present results from laboratory friction experiments where a halite (NaCl) slider held under constant load is dragged across a coarse substrate. Surface evolution and frictional resistance are recorded. Heat emission at the sliding surface is monitored using an infra-red camera. We demonstrate a link between plastic deformations of halite and enhanced heating characterized by transient localized heat spots. When sand 'gouge' is added to the interface, heating is more diffuse. Importantly, when strong asperities concentrate deformation, significantly more heat is produced locally. In natural faults such regions could be nucleation patches for melt production and hence potentially initiate weakening during earthquakes at much smaller sliding velocities or shear stress than previously thought

A short comment on the early development of Odense

In a recent overview of the material from eighth to twelfth century Odense, Runge and Henriksen propose to move the date of the town’s foundation by a hundred years, to the early tenth century. In this brief comment we challenge their interpretation of the earliest Odense, and point to some problems with their definition of what constitutes towns and proto-towns, as well as the analysis of the material they present

Identifying and correcting spatial bias in opportunistic citizen science data for wild ungulates in Norway

Many publications make use of opportunistic data, such as citizen science observation data, to infer large-scale properties of species’ distributions. However, the few publications that use opportunistic citizen science data to study animal ecology at a habitat level do so without accounting for spatial biases in opportunistic records or using methods that are difficult to generalize. In this study, we explore the biases that exist in opportunistic observations and suggest an approach to correct for them. We first examined the extent of the biases in opportunistic citizen science observations of three wild ungulate species in Norway by comparing them to data from GPS telemetry. We then quantified the extent of the biases by specifying a model of the biases. From the bias model, we sampled available locations within the species’ home range. Along with opportunistic observations, we used the corrected availability locations to estimate a resource selection function (RSF). We tested this method with simulations and empirical datasets for the three species. We compared the results of our correction method to RSFs obtained using opportunistic observations without correction and to RSFs using GPS-telemetry data. Finally, we compared habitat suitability maps obtained using each of these models. Opportunistic observations are more affected by human access and visibility than locations derived from GPS telemetry. This has consequences for drawing inferences about species’ ecology. Models naïvely using opportunistic observations in habitat-use studies can result in spurious inferences. However, sampling availability locations based on the spatial biases in opportunistic data improves the estimation of the species’ RSFs and predicted habitat suitability maps in some cases. This study highlights the challenges and opportunities of using opportunistic observations in habitat-use studies. While our method is not foolproof it is a first step toward unlocking the potential of opportunistic citizen science data for habitat-use studiespublishedVersio

A dataset of direct observations of sea ice drift and waves in ice

Variability in sea ice conditions, combined with strong couplings to the atmosphere and the ocean, lead to a broad range of complex sea ice dynamics. More in-situ measurements are needed to better identify the phenomena and mechanisms that govern sea ice growth, drift, and breakup. To this end, we have gathered a dataset of in-situ observations of sea ice drift and waves in ice. A total of 15 deployments were performed over a period of 5 years in both the Arctic and Antarctic, involving 72 instruments. These provide both GPS drift tracks, and measurements of waves in ice. The data can, in turn, be used for tuning sea ice drift models, investigating waves damping by sea ice, and helping calibrate other sea ice measurement techniques, such as satellite based observations

Moving in the anthropocene: global reductions in terrestrial mammalian movements

Animal movement is fundamental for ecosystem functioning and species survival, yet the effects of the anthropogenic footprint on animal movements have not been estimated across species. Using a unique GPS-tracking database of 803 individuals across 57 species, we found that movements of mammals in areas with a comparatively high human footprint were on average one-half to one-third the extent of their movements in areas with a low human footprint. We attribute this reduction to behavioral changes of individual animals and to the exclusion of species with long-range movements from areas with higher human impact. Global loss of vagility alters a key ecological trait of animals that affects not only population persistence but also ecosystem processes such as predator-prey interactions, nutrient cycling, and disease transmission

The economy of Norwegian towns c. 1250-1350. A comparative study of the economic functions of towns in Norway, Denmark and England.

The aim of this thesis is to explain why differences arose between Norwegian, Danish and English towns with regard to their economic functions. Norwegian towns did not develop a sizeable production of commodities for the rural hinterland, something Danish and English towns did, of which the textile industry in small English towns is a prime example. This production contributed to the growth of towns in Denmark and England, a growth that was quite explosive in the thirteenth century. The thesis investigates the scant evidence there is for urban production in Norway, and compares it with the production of goods in English and Danish towns. The differences are explained by looking at how commercialised Norwegian, English and Danish societies were, and what factors could have caused the differences in the levels of commercialisation that can be observed. The factors that were considered to have had the most impact are geography, topography, climate and population, the relationship between the landowning class and the peasants, and the dominating position of merchants from the Hanse

The beat of the mountain: a transdisciplinary rhythmanalysis of temporal landscapes

This article discusses how studying rhythms can help us better understand and manage spatiotemporal tensions in social-ecological landscapes, highlighting the potential of rhythmanalysis as a tool for crossing scientific and methodological borders. The empirical material is from a study of human and non-human users and uses of the highly valued Dovrefjell mountain area in Norway, with particular attention to the much-debated Snøheim Road. We take an in-depth view of Three different, but interrelated, rhythms at Dovrefjell and discuss how intervening through rhythms can be a fruitful way to approach landscape management. By simultaneously ‘listening’ to different rhythms, this approach helps us to understand and reduce spatiotemporal tensions between social, cultural and ecological uses of a landscape. Landscape; rhythmanalysis; interdisciplinarity; wild reindeer; recreation; land management; Dovrefjell; NorwayacceptedVersio

Silhuett Rondane – Hvordan bevare villreinen

NINA presenterer her hovedfunn fra GPS-merkeprosjektet om villrein og ferdsel i Rondane i perioden 2009-2019. Temaheftet retter seg mot politikere, forvaltere og andre interessegrupper som har som mål å ta vare på villreinen og å finne gode løsninger mellom bruk og vern av fjellet. Vi viser til Rondane-rapporten (Strand et al. 2014) for beskrivelse av styringsgruppa sitt mandat og medlemmer. Temaheftet bygger på en internettbasert kartfortelling og vi anbefaler www.villrein.no for interaktive fortellinger om villreinen i Rondane og andre villreinstammer i Norge. Villreinen i Rondane har store utfordringer pga. menneskelige inngrep og aktivitet. Rondane et viktig reisemål med stor betydning for regionen og bygdene rundt. Det er en krevende oppgave å sørge for bedre sameksistens mellom mennesker og villrein. Forskning har dokumentert utfordringene som dyra står ovenfor og èn har lyktes med å finne forslag til flere tiltak som kan bedre forholdene. Tiltak i denne sammenheng handler i første rekke om å endre bruken av området gjennom konkret arealforvaltning, informasjon og veiledning av de besøkende. De foreslåtte tiltakene bygger på kunnskap om villrein og ferdsel, men hva som er rett eller galt å gjøre på det enkelte sted handler om politikk og verdivalg. Vi håper temaheftet gir økt kunnskap og kan inspirere til å ta vare på den genetisk unike villreinstammen i Rondane

Silhuett Rondane – Hvordan bevare villreinen

NINA presenterer her hovedfunn fra GPS-merkeprosjektet om villrein og ferdsel i Rondane i perioden 2009-2019. Temaheftet retter seg mot politikere, forvaltere og andre interessegrupper som har som mål å ta vare på villreinen og å finne gode løsninger mellom bruk og vern av fjellet. Vi viser til Rondane-rapporten (Strand et al. 2014) for beskrivelse av styringsgruppa sitt mandat og medlemmer. Temaheftet bygger på en internettbasert kartfortelling og vi anbefaler www.villrein.no for interaktive fortellinger om villreinen i Rondane og andre villreinstammer i Norge. Villreinen i Rondane har store utfordringer pga. menneskelige inngrep og aktivitet. Rondane et viktig reisemål med stor betydning for regionen og bygdene rundt. Det er en krevende oppgave å sørge for bedre sameksistens mellom mennesker og villrein. Forskning har dokumentert utfordringene som dyra står ovenfor og èn har lyktes med å finne forslag til flere tiltak som kan bedre forholdene. Tiltak i denne sammenheng handler i første rekke om å endre bruken av området gjennom konkret arealforvaltning, informasjon og veiledning av de besøkende. De foreslåtte tiltakene bygger på kunnskap om villrein og ferdsel, men hva som er rett eller galt å gjøre på det enkelte sted handler om politikk og verdivalg. Vi håper temaheftet gir økt kunnskap og kan inspirere til å ta vare på den genetisk unike villreinstammen i Rondane.publishedVersio