Opportunities and challenges with new railway planning approach in Sweden

Long lead times in railway planning can give rise to a significant discrepancy between the original plan and the traffic eventually operated, resulting in inefficient utilization of capacity. Research shows that the railway sector in Sweden would benefit from a different planning approach in which capacity consuming decisions are pushed forward in time whenever possible. This approach is currently being implemented at Trafikverket, the Swedish Transport Administration. With it follows a number of mathematical opportunities and challenges, some of which will be presented in this paper

On the delivery robustness of train timetables with respect to production replanning possibilities

Measuring timetable robustness is a complex task. Previous efforts have mainly been focused on simulation studies or measurements of time supplements. However, these measurements don't capture the production flexibility of a timetable, which is essential for measuring the robustness with regard to the trains' commercial activity commitments, and also for merging the goals of robustness and efficiency. In this article we differentiate between production timetables and delivery timetables. A production timetable contains all stops, meetings and switch crossings, while a delivery timetable only contains stops for commercial activities. If a production timetable is constructed such that it can easily be replanned to cope with delays without breaking any commercial activity commitments it provides delivery robustness without compromising travel efficiency. Changing meeting locations is one of the replanning tools available during operation, and this paper presents a new framework for heuristically optimising a given production timetable with regard to the number of alternative meeting locations. Mixed integer programming is used to find two delivery feasible production solutions, one early and one late. The area between the two solutions represents alternative meeting locations and therefore also the replanning enabled robustness. A case study from Sweden demonstrates how the method can be used to develop better production timetables

The Maraca: a tool for minimizing resource conflicts in a non-periodic railway timetable

While mathematical optimization and operations research receive growing attention in the railway sector, computerized timetabling tools that actually make significant use of optimization remain relatively rare. SICS has developed a prototype tool for non-periodic timetabling that minimizes resource conflicts, enabling the user to focus on the strategic decisions. The prototype is called the Maraca and has been used and evaluated during the railway timetabling construction phase at the Swedish Transport Administration between April and September 2010

Digitala tjänster för co-modal trafiksynkronisering i Göta älv-området

Detta dokument sammanfattar det som har framkommit under en mindre förstudie inom ramen för projektet "Utveckling av innovativa, kundorienterade IT-baserade järnvägstjänster". Målet med förstudien var att undersöka dagens förutsättningar för att synkronisera co-modala skärningspunkter, med broöppningar som konkret exempel. Studien har tittat på vilken information som påverkar beslut om broöppningar med avsikt att kunna ge en indikation på vilka mekanismer och vilken information som skulle behövas från Trafikverkets perspektiv för att möjliggöra smidigare broöppningar för sjöfarten. Den faktor som enligt förstudien påverkar broöppningsmöjligheterna mest är bristen på tydliga riktlinjer för hur olika trafikslag ska prioriteras

'O neighbour, where art thou?'

The organisation of individuals in space and time influences population structure and dynamics, and is important for our understanding of animal ecology. The aim of this thesis is to gain an increased understanding of the mechanisms driving the abundance and distribution of solitary carnivores, from individual space use to population-level distribution. I used individual-level spatial and demographic data from Eurasian lynx (Lynx lynx) and wolverines (Gulo gulo), collected over more than 20 years in multiple areas within Scandinavia, to assess space use determinants and link territorial dynamics to dispersal patterns. For lynx, female total home range size declined as roe deer and lynx density increased. Male total home range size also declined with higher lynx density, while prey only became important for determining the size of more intensively used areas within the home range. There is also a positive effect of roe deer abundance on lynx survival in south-central Sweden. Roe deer is a predictable prey source compared to migrating reindeer, the main prey for lynx in northern Sweden. I found that home range overlap between neighbouring lynx increased with their relatedness (mother-daughter) for females in northern Sweden, but not for males nor females in the south. This finding suggests inclusive fitness benefits of sharing an unpredictable and highly seasonal food source with known relatives. The wolverine study population was characterized by a stable distribution of resident individuals with high territorial fidelity. When a territory became vacant in the study area, it was almost exclusively reoccupied by a female from the surrounding area. The availability of a young female’s natal territory substantially increased the probability of her establishing in the study area. Furthermore, the probability of a young female leaving the study area increased as the number of available territories decreased. This finding suggests that the study population is saturated, with limited room for dispersers to establish, which suggests that emigration to surrounding areas is related to survival of resident females. Wolverines in Sweden have expanded into boreal forests south and east of alpine areas. However, the recolonised areas with limited snow cover remain largely unmonitored. Most females gave birth in natal dens in mid-February, and rarely moved their cubs between den sites for the first two months, while lactating and while prey availability was low. After weaning, den shifting over longer distances increased, matching the seasonal increase in prey availability. Increased knowledge of spatial and social dynamics can give insights into how these populations are influenced by human activity, as well as the outcome of management actions

Järvhonors revirdynamik

Spatial and social systems form the organisation of animals in space and time and are important aspects of animal ecology due to their effect on population dynamics and structure. In this study I investigate territorial dynamics of female wolverines, with particular focus on interannual territorial fidelity and reoccupation of territories vacated due to death of territorial females. To do this, I used location data and den site locations of adult female wolverines (n = 58), collected from 1993-2008 in and around Sarek National Park, northern Sweden. I found that female wolverines exhibited high interannual fidelity to territory. Resident females (n = 34) were monitored for a total of 145.9 wolverine years, and only twelve females moved from their territories one or more times during the study, resulting in a total of 14 vacated territories. Hence, 9.6% of resident females moved from their territories annually. Fifty-eight percent of the females (n = 7/12) that abandoned their territories established new territories, with a mean distance of 11.7 km between dens in their old and new territories. Sixteen (70%) of territories vacated due to death of a resident female (n = 23) were reoccupied by a replacing female. The mean territory overlap between the deceased female and her replacer was 75% (range 57-87). Sixty-nine percent of replacers (n = 16) occupied vacated territories within a year. There was a new reproduction the first year after the territory was vacated in 30% of all the vacated territories (n = 23). The time from reoccupation to first reproduction in the territory was significantly longer for juvenile and subadult replacers than for adult replacers. I found that 54% of the marked replacers were daughters and 15% were granddaughters of the deceased female. Every time a daughter was still present in the territory when her mother died, the daughter occupied the vacated territory. My results suggest that the spatial organization of female wolverine territories in Scandinavia is characterized by long-term stability, as vacated territories are generally occupied by new individuals rather than absorbed by neighbours. Furthermore, in a population that is saturated with territories, deceased females are generally replaced by females from the local population, and primarily daughters if they are still present in the territory when their mother dies. Hence, local density of territorial females is resumed while emigration is decreased, which can have implications for adjacent populations. I also showed that the time from reoccupation to first reproduction for the replacing females varied considerably. This is important from a Swedish management perspective, as the local density, and possibly predation pressure, might recover quickly after removal of territorial females, while the amount of economical compensation, based on number of wolverine reproductions, to reindeer herding districts for predation losses is reduced until next reproduction in the territory. My study shows that the reoccupation process and time to next reproduction, effects on local density and emigration are important factors to consider when using removal of individuals to decrease predation pressure The demographic importance of female survival for population growth is further emphasized by my results, which shows the strong influence of adult female survival on territorial dynamics and dispersal, and hence its effect on a larger scale

Wolverine denning behaviour and its implications for monitoring reproductive females

Knowledge about the number of reproductive females is important for monitoring population dynamics, and can be critical for managing human-wildlife conflicts. For wolverines Gulo gulo, counts of reproductive females is the basis for estimates of population size in Scandinavia, as well as a key measure for compensation payments to Sami reindeer-herders in Sweden. However, documenting wolverine reproductive events in the field is challenging and requires knowledge of female denning behaviour. Furthermore, females may shift den sites, presenting difficulties in determining whether two den sites belong to the same or two neighbouring females. In this study, we used data from 18 GPS-collared wolverine females, monitored intensively during the denning season (15 February-31 May) in 2004-2014, to provide baseline information on denning behaviour. We documented reproductive events in 32 of 54 potential denning seasons, and identified a total of 245 den sites. Females used 8.8 +/- 8.5 (mean +/- SD) den sites per denning season (median = 6, range: 1-28). The number of den site shifts, the distance between subsequent den sites, and the time and distance females spent away from a den site increased during the denning season; while distances between neighbouring females' den sites remained constant. From late April, the distance between consecutive den sites used by the same female overlapped with distances between neighbouring females' den sites, resulting in increased uncertainty regarding whether two den sites belonged to one or two females. Using Bayesian modelling we calculated probabilities that two den sites belonged to the same female, or neighbouring females, conditional on the time of season and the distance between den sites. These findings will allow the monitoring program to adapt its methods for determining if multiple den sites belong to one or two reproductive events, using seasonally-dynamic threshold based on an understanding of wolverine denning behaviour

Sample identification and pedigree reconstruction in Wolverine (Gulo gulo) using SNP genotyping of non-invasive samples

For conservation genetic studies using non-invasively collected samples, genome-wide data may be hard to acquire. Until now, such studies have instead mostly relied on analyses of traditional genetic markers such as microsatellites (SSRs). Recently, high throughput genotyping of single nucleotide polymorphisms (SNPs) has become available, expanding the use of genomic methods to include non-model species of conservation concern. We have developed a 96-marker SNP array for use in applied conservation monitoring of the Scandinavian wolverine (Gulo gulo) population. By genotyping more than a thousand non-invasively collected samples, we were able to obtain precise estimates of different types of genotyping errors and sample dropout rates. The SNP panel significantly outperforms the SSR markers (and DBY intron markers for sexing) both in terms of precision in genotyping, sex assignment and individual identification, as well as in the proportion of samples successfully genotyped. Furthermore, SNP genotyping offers a simplified laboratory and analysis pipeline with fewer samples needed to be repeatedly genotyped in order to obtain reliable consensus data. In addition, we utilised a unique opportunity to successfully demonstrate the application of SNP genotype data for reconstructing pedigrees in wild populations, by validating the method with samples from wild individuals with known relatedness. By offering a simplified workflow with improved performance, we anticipate this methodology will facilitate the use of non-invasive samples to improve genetic management of many different types of populations that have previously been challenging to survey

Recolonization following past persecution questions the importance of persistent snow cover as a range limiting factor for wolverines

Globally, climate is changing rapidly, which causes shifts in many species' distributions, stressing the need to understand their response to changing environmental conditions to inform conservation and management. Northern latitudes are expected to experience strongest changes in climate, with milder winters and decreasing snow cover. The wolverine (Gulo gulo) is a circumpolar, threatened carnivore distributed in northern tundra, boreal, and subboreal habitats. Previous studies have suggested that wolverine distribution and reproduction are constrained by a strong association with persistent spring snow cover. We assess this hypothesis by relating spatial distribution of 1589 reproductive events, a fitness-related proxy for female reproduction and survival, to snow cover over two decades. Wolverine distribution has increased and number of reproductive events increased 20 times in areas lacking spring snow cover during our study period, despite low monitoring effort where snow is sparse. Thus, the relationship between reproductive events and persistent spring snow cover weakened during this period. These findings show that wolverine reproductive success and hence distribution are less dependent on spring snow cover than expected. This has important implications for projections of future habitat availability, and thus distribution, of this threatened species. Our study also illustrates how past persecution, or other factors, that have restricted species distribution to remote areas can mask actual effects of environmental parameters, whose importance reveals when populations expand beyond previously restricted ranges. Overwhelming evidence shows that climate change is affecting many species and ecological processes, but forecasting potential consequences on a given species requires longitudinal data to revisit hypotheses and reassess the direction and magnitude of climate effects with new data. This is especially important for conservation-oriented management of species inhabiting dynamic systems where environmental factors and human activities interact, a common scenario for many species in different ecosystems around the globe

No Allee effect detected during the natural recolonization by a large carnivore despite low growth rate

Eurasian lynx (Lynx lynx) have recently naturally recolonized southern Sweden. The first documented reproduction of lynx in recent times occurred in 2003, and the population increased from 2 to 48 family groups (the unit of measurement in Swedish monitoring) during its first 18 years (2003/2004-2020/2021). We did not detect any Allee effect, that is, lower growth rate at low population density, during the recolonization of southern Sweden, although our population simulations revealed a non-negligible (30%) chance that population observed development could include an Allee effect. The probable absence of an Allee effect was likely because colonizing females did not lack mating partners, as a larger number of wide-ranging males were established in the area before documented reproduction took place. Despite the absence of an Allee effect, the growth rate during recolonization was lower in southern Sweden (lambda = 1.20) than in central Sweden (lambda = 1.29). We have no evidence of higher mortality, including that from poaching, or lower reproduction in southern Sweden could explain the lower growth rate. Instead, we suggest that the lower growth rate during the recolonization of southern Sweden was explained by fewer immigrants arriving from central Sweden due to areas of less suitable habitat between central and southern Sweden, partially preventing immigration southward. From a conservation point of view, it is positive that this small population could recover without being negatively influenced by an Allee effect, as small populations with an Allee effect experience lower viability than those without