Resources and predation: drivers of sociality in a cyclic mesopredator

In socially fexible species, the tendency to live in groups is expected to vary through a trade-of between costs and benefts, determined by ecological conditions. The Resource Dispersion Hypothesis predicts that group size changes in response to patterns in resource availability. An additional dimension is described in Hersteinsson’s model positing that sociality is further afected by a cost–beneft trade-of related to predation pressure. In the arctic fox (Vulpes lagopus), group-living follows a regional trade-of in resources’ availability and intra-guild predation pressure. However, the efect of local fuctuations is poorly known, but ofers an unusual opportunity to test predictions that difer between the two hypotheses in systems where prey availability is linked to intra-guild predation. Based on 17-year monitoring of arctic fox and cyclic rodent prey populations, we addressed the Resource Dispersion Hypothesis and discuss the results in relation to the impact of predation in Hersteinsson’s model. Group-living increased with prey density, from 7.7% (low density) to 28% (high density). However, it remained high (44%) despite a rodent crash and this could be explained by increased benefts from cooperative defence against prey switching by top predators. We conclude that both resource abundance and predation pressure are factors underpinning the formation of social groups in fuctuating ecosystems.publishedVersio

Smart electric vehicle charging strategies for sectoral coupling in a city energy system

The decarbonization of city energy systems plays an important role to meet climate targets. We examine the consequences of integrating electric cars and buses into the city energy system (60% of private cars and 100% of public buses), using three different charging strategies in a modelling tool that considers local generation and storage of electricity and heat, electricity import to the city, and investments to achieve net-zero emissions from local electricity and heating in 2050. We find that up to 85% of the demand for the charging of electric cars is flexible and that smart charging strategies can facilitate 62% solar PV in the charging electricity mix, compared to 24% when cars are charged directly when parked. Electric buses are less flexible, but the timing of charging enables up to 32% to be supplied by solar PV. The benefit from smart charging to the city energy system can be exploited when charging is aligned with the local value of electricity in the city. Smart charging for cars reduces the need for investments in stationary batteries and peak units in the city electricity and heating sectors. Thus, our results point to the importance of sectoral coupling to exploit flexibility options in the city electricity, district heating and transport sectors

Spatial distribution in Norwegian lemming Lemmus lemmus in relation to the phase of the cycle

Competition between individuals of the same or different species affects spatial distribution of organisms at any given time. Consequently, a species geographical distribution is related to population dynamics through density-dependent processes. Small Arctic rodents are important prey species in many Arctic ecosystems. They commonly show large cyclic fluctuations in abundance offering a potential to investigate how landscape characteristics relates to density-dependent habitat selection. Based on long-term summer trapping data of the Norwegian lemming (Lemmus lemmus) in the Scandinavian Mountain tundra, we applied species distribution modeling to test if the effect of environmental variables on lemming distribution changed in relation to the lemming cycle. Lemmings were less habitat specific during the peak phase, as their distribution was only related to primary productivity. During the increase phase, however, lemming distribution was, in addition, associated with landscape characteristics such as hilly terrain and slopes that are less likely to get flooded. Lemming habitat use varied during the cycle, suggesting density-dependent changes in habitat selection that could be explained by intraspecific competition. We believe that the distribution patterns observed during the increase phase show a stronger ecological signal for habitat preference and that the less specific habitat use during the peak phase is a result of lemmings grazing themselves out of the best habitat as the population grows. Future research on lemming winter distribution would make it possible to investigate the year around strategies of habitat selection in lemmings and a better understanding of a fundamental actor in many Arctic ecosystems.publishedVersio

Variation in albedo and other vegetation characteristics in non-forested northern ecosystems: the role of lichens and mosses

Vegetation has a profound impact on climate through complex interactions and feedback loops, where especially regulation of albedo, the ratio of reflected to incoming solar radiation, is important at high latitudes. How vegetation albedo varies along environmental gradients in tundra ecosystems is still not well understood, particularly for ecosystems dominated by nonvascular vegetation. We studied broadband shortwave albedo of open boreal, arctic, and alpine ecosystems over a 2000 km long latitudinal gradient (60◦ N–79◦ N) and contrasted this against species composition, vegetation greenness (normalised difference vegetation index—NDVI), momentary ecosystem CO2 fluxes and reindeer (Rangifer tarandus) grazing pressure. High cover of pale terricolous fruticose lichens was the single most important predictor for vegetation albedo, which had a maximum value of 0.389 under clear sky conditions and solar zenith angle 60◦. To our knowledge, this is the highest broadband albedo recorded for a vegetated surface. NDVI was negatively correlated to lichen biomass (rs = −0.56), and albedo (rs = −0.19). Gross primary production and ecosystem respiration varied considerably less between plots and vegetation types than albedo. While it is well-known that Rangifer affects climate-relevant aboveground biomass, we here show that its regulation of surface albedo in northern ecosystems may also be of high importance for land-atmosphere interactions. The data presented here thus advocate for an increased understanding of the important and complex role of herbivores and lichen cover in climate-vegetation interactions.publishedVersio

An artificial intelligence approach to remotely assess pale lichen biomass

Although generally given little attention in vegetation studies, ground-dwelling (terricolous) lichens are major contributors to overall carbon and nitrogen cycling, albedo, biodiversity and biomass in many high-latitude ecosystems. Changes in biomass of mat-forming pale lichens have the potential to affect vegetation, fauna, climate and human activities including reindeer husbandry. Lichens have a complex spectral signature and terricolous lichens have limited growth height, often growing in mixtures with taller vegetation. This has, so far, prevented the development of remote sensing techniques to accurately assess lichen biomass, which would be a powerful tool in ecosystem and ecological research and rangeland management. We present a Landsat based remote sensing model developed using deep neural networks, trained with 8914 field records of lichen volume collected for > 20 years. In contrast to earlier proposed machine learning and regression methods for lichens, our model exploited the ability of neural networks to handle mixed spatial resolution input. We trained candidate models using input of 1 x 1 (30 x 30 m) and 3 x 3 Landsat pixels based on 7 reflective bands and 3 indices, combined with a 10 m spatial resolution digital elevation model. We normalised elevation data locally for each plot to remove the region-specific variation, while maintaining informative local variation in topography. The final model predicted lichen volume in an evaluation set (n = 159) reaching an R2 of 0.57. NDVI and elevation were the most important predictors, followed by the green band. Even with moderate tree cover density, the model was efficient, offering a considerable improvement compared to earlier methods based on specific reflectance. The model was in principle trained on data from Scandinavia, but when applied to sites in North America and Russia, the predictions of the model corresponded well with our visual interpretations of lichen abundance. We also accurately quantified a recent historic (35 years) change in lichen abundance in northern Norway. This new method enables further spatial and temporal studies of variation and changes in lichen biomass related to multiple research questions as well as rangeland management and economic and cultural ecosystem services. Combined with information on changes in drivers such as climate, land use and management, and air pollution, our model can be used to provide accurate estimates of ecosystem changes and to improve vegetation-climate models by including pale lichens.Peer reviewe

Spatial and temporal population dynamics in the mountain tundra – mesopredator and prey

It is well known that competition, predation and fluctuating food resources can have strong effect on individual fitness and population dynamics. The complexity of natural systems can make it complicate to disentangle those processes, but environments with relatively simple food webs, and strong cyclic population dynamics offer contrasting conditions resembling experimental treatments. This thesis concerns the spatial and temporal implications of fluctuations in small rodent abundance on two trophic levels in a highly cyclic ecosystem, the Scandinavian mountain tundra. The first two chapters focus on plant biomass and spatiotemporal distribution in the Norwegian lemming (Lemmus lemmus), while the three last papers focus on the direct and indirect effects of small rodent fluctuations and territory quality on reproductive success, juvenile survival and group living in a lemming specialist mesopredator, the arctic fox (Vulpes lagopus). By developing, validating and applying a novel application of aerial photos for remote sensing of plant biomass (Chapter I), we found that food availability predicted lemming distribution during population peaks, but that they were more habitat specific during increase years when intraspecific competition was lower (Chapter II). Arctic fox reproduction is tightly connected to small rodent abundance but the effects of geographical variation in food availability is less well known. We used 17 years of population surveys of an arctic fox subpopulation in mid Sweden (Helagsfjällen) to investigate potential effects. During small rodent increase years, we found that arctic fox litter sizes were smaller in territories of intermediate plant productivity, compared to both more and less productive territories (Chapter III). This could be an effect of limited food availability together with increased presence of red foxes (Vulpes vulpes), a stronger and potentially lethal competitor. However, when small rodents peaked, and competition would be expected to decrease, we saw no effect of territory productivity. Based on a smaller data set concerning juvenile summer survival, we found that the mortality rate among juveniles born by first time breeding arctic fox females were more sensitive to low small rodent prey abundance (Chapter IV). We explain it with an increased predation pressure from top-predators that switch from small rodents to alternative prey when small rodents decline, as suggested by an observed positive effect on juvenile survival by adult presence on den sites. Arctic foxes are socially flexible, and several adults can share a den with the resident pair, potentially increasing juvenile survival and help in territorial defence. Returning to the 17-year data set, we tested the Resource Dispersion Hypothesis predicting that increased resource availability should increase group size (Chapter V). We found support for this prediction as group living increased during the small rodent peak phase. However, it remained unexpectedly high during the decrease phase, when resources are scarce. This could however be related to increased predation pressure, and an increasing benefit of group living.At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 1: Manuscript. Paper 3: Manuscript. Paper 5: Manuscript.</p

A retrospective cohort study evaluating the risk of re-arthroscopy two years after Anterior Cruciate Ligament reconstruction

Introduction: The Anterior Cruciate ligament (ACL) is one of the most important ligaments in the knee providing joint stability. Rupture of ACL is the most common sports injury. About half of the patients undergo surgical reconstruction. The Orthopaedic clinic in Region Örebro county underwent a reorganization in 2016. Aim: The aim of this study was to evaluate the two-year risk of re-arthroscopy in the same knee after primary ACL-reconstruction. Material and Methods: A retrospective cohort study. All patients from 1st January 2005 until 31st December 2017 with primary ACL reconstruction in Region Örebro county were included. Data was collected from medical records and The Swedish National Anterior Cruciate Ligament Register. Results: 431 patients were included. The total risk of re-arthroscopy was 13.0%. Meniscal surgeries and age did not affect the outcome. Fixation method in femur and tibia affected the outcome, as did choice of graft. There was a small numerical difference before (13.4%) vs after (12.1%) the reorganization, but it was not statistically significant either unadjusted or adjusted for age and meniscal surgeries (p=0.721). Conclusions: Our study indicates that choice of graft and fixation method in femur and tibia affect the re-arthroscopy rate. Regarding graft, the semitendinosus tendon alone was the better option, and for fixation both for femur and tibia it seems like Tightrope was the best option and screw the worst. The reorganization did not affect the outcome but might have other benefits

Långtida markanvändningsförändringar i jordbruket på Ingmarsö

Traditionellt skötta jordbrukslandskap hyser några av Sveriges mest artrika naturtyper, i huvudsak öppna gräsmarker till vilka en stor del av Sveriges hotade kärlväxter är knutna. Jordbrukets utveckling sedan 1800-talets slut har lett till kraftig minskning av gräsmarker och sämre kvalitet hos de kvarvarande. Skärgårdsjordbruket har små möjligheter till storskalighet och har inte haft samma effektiviseringstryck på sig som jordbruk på fastlandet. Det kan alltså tänkas ha behållit äldre tiders småskalighet – i de fall det fortfarande bedrivs – och därmed stora naturvärden. Studien är en jämförelse mellan jordbrukets utveckling i skärgården och på fastlandet, baserat på GIS-analys av historiska kartdata kompletterat med fältstudier och intervjuer. Undersökningsområdena omfattar Ingmarsö i Stockholms skärgård och Myra, norr om Norrtälje. Arbetet omfattar också en GIS-baserad hävdanalys där gräsmarker klassats utifrån historisk markanvändning. Resultatet är tänkt att vara ett hjälpmedel i restaureringsprojekt genom att ringa in marker med potentiellt höga naturvärden. Reslutatet visar att skärgårdsjordbruket gått tillbaka men behållit sin småskalighet och förblivit aktivt. Till skillnad från det undersökta fastlandsjordbruket som så gott som upphörde innan 1950-talet. Hypotesen att skärgårdsjordbruket skulle vara mindre påverkat av jordbrukets allmäna utveckling bekräftas alltså, men då studien inte bygger på replikat går det inte att dra några generella slutsater. Ett flertal tänkbara förklaringar finns, bland annat skärgårdsbondens bredare försörjningsbas med möjlighet till fiske och intäkter från sommargäster. Hävdanalysen ringar in ett flertal områden som kan vara intressanta föremål för restaurering, men inventeringar krävs för att utvärdera analysmetoden

A retrospective cohort study evaluating the risk of re-arthroscopy two years after Anterior Cruciate Ligament reconstruction

Introduction: The Anterior Cruciate ligament (ACL) is one of the most important ligaments in the knee providing joint stability. Rupture of ACL is the most common sports injury. About half of the patients undergo surgical reconstruction. The Orthopaedic clinic in Region Örebro county underwent a reorganization in 2016. Aim: The aim of this study was to evaluate the two-year risk of re-arthroscopy in the same knee after primary ACL-reconstruction. Material and Methods: A retrospective cohort study. All patients from 1st January 2005 until 31st December 2017 with primary ACL reconstruction in Region Örebro county were included. Data was collected from medical records and The Swedish National Anterior Cruciate Ligament Register. Results: 431 patients were included. The total risk of re-arthroscopy was 13.0%. Meniscal surgeries and age did not affect the outcome. Fixation method in femur and tibia affected the outcome, as did choice of graft. There was a small numerical difference before (13.4%) vs after (12.1%) the reorganization, but it was not statistically significant either unadjusted or adjusted for age and meniscal surgeries (p=0.721). Conclusions: Our study indicates that choice of graft and fixation method in femur and tibia affect the re-arthroscopy rate. Regarding graft, the semitendinosus tendon alone was the better option, and for fixation both for femur and tibia it seems like Tightrope was the best option and screw the worst. The reorganization did not affect the outcome but might have other benefits

ANALYS AV KOSTNADER FÖR LAST MILE DISTRIBUTION : MÖJLIGHETER MED KONSOLIDERING OCH DESS SYNERGIEFFEKTER

I dagsläget lever 86 % av Sveriges befolkning i stadsområden. Mellan år 1990 till 2015 ökade befolkningen i Sveriges största storstadsområden med ca 26 % i Göteborg, ca 36 % i Stockholm och ca 31 % i Malmö. Detta har skapat hårdare konkurrens i fråga om ytan mellan bland annat bostäder, näringsliv, grönområden och transportinfrastrukturen. Det är viktigt att redan i planeringsfasen vid städernas utformning väga in aspekterna för citydistributionen och skapa ett balanserat transportsystem. Vid ökade transporter inom en stad ökar faktorer så som köer, trängsel, koldioxidutsläpp, kostnader, stress och olyckor. Syftet med undersökningen var att genom signifikanta teorier och datainsamling beräkna kostnadsfördelningen av distributörernas ”last mile distribution”. Även ge underlag för att visualisera konsoliderings- och samlastningsmöjligheter där antalet utlämnings- och upphämtningsstopp var tätare. Arbetet begränsades till ett område inom Göteborgs innerstad och fordonstypen till paketbilar. Datainsamlingsperioden skedde från och med den 23 mars 2016 till och med 25 april 2016. De teorier som låg till grund för arbetet är supply chain, distribution, citydistribution, Triple bottom line, kostnader för citydistribution, samlastning och konsolidering. Uppsatsen utgick ifrån kvantitativa metoder och värdena analyserades från en objektiv ståndpunkt. För att skaffa en grunduppfattning av last mile utfördes även två semistrukturerade kvalitativa intervjuer. De utvalda respondenterna är forskare inom logistik. Primärdata till uppsatsen är insamlad genom en tidsstudie med hjälp av applikationen Stardriver. Detta utfördes under 13 hela arbetsdagar tillsammans med marknadsledande distributionsfirmor inom paket och logistik i Sverige. Resultatet påvisar att kostnadsfördelningen inom last mile till störst del fördelas på aktiviteterna Drive, Handle to store och Unload. Aktiviteterna delades också in beroende på om de är värdeskapande, stödjande eller förluster. Kontentan av det blev att 70% är värdeskapande aktiviteter, 13% stödjande aktiviteter och 17% är rena förluster. Detta innebär att under ett kalenderår lägger distributören på ett ungefär 501 269 kr på värdeskapande aktiviteter, 93 093 kr på stödjande aktiviteter och 121 737 kr på förluster. De aktiviteter som klassas som förlust bör elimineras för att minska kostnaderna. Även de andra aktiviteterna kan skapa mer kostnadseffektiva transporter genom exempelvis samlastning mellan distributörer och intern effektivisering. Möjligheterna för samlastning och konsolidering av paket inom centrala områden i Göteborgs är goda enligt det data som samlades in. Baserat på den tätare kundkrets som påträffades inom den begränsade ytan upprättades två mindre områden där samlastning med fördel kan nyttjas. För att implementera samlastning mellan distributörerna krävs ett starkare samarbete mellan parterna. Alternativt att en oberoende part så som Stadleveransen som tar hand om distributionen.