<p> In this thesis, the postglacial spread of three ecologically distinct species, Picea mariana (black spruce), Picea glauca (white spruce), and Pinus banksiana (jack pine), across the western interior of Canada are presented. The fossil pollen records from the sediments of thirteen lakes are used in reconstructing the population expansions of the three tree taxa. The objectives of this study are to examine temporal and spatial patterns in the growth of the populations and to determine if intraspecific and interspecific variations exist across a range of latitudes and elevations.</p> <p> Pollen accumulation rates (PAR) are calculated from pollen grain counts and sedimentation rates throughout the early-to mid-Holocene, and are used to represent the population level at the time of pollen deposition. Exponential equations are used to calculate population growth rates. Three dimensional diagrams (time, space, abundance) are constructed to illustrate the spread of the populations.</p> <p> The rates of population growth varied from south to north for all three species. Jack pine, on average had slower population growth rates, and its expansion across the region began over 3,000 years later than, and lasted approximately 1,000 years longer than the two spruce species. All three tree taxa experienced reduced rates of population growth at high elevation sites in the north. These variations are examined in light of the changing and static physical and botanical environmental conditions occurring during expansion.</p> / Thesis / Master of Science (MSc)

This dissertation has two main objectives: first, quantify the effects of environmental conditions on spatio-temporal spawning and larval dynamics of zebra mussels (Dreissena polymorpha [Pallas 1771]) in Lake Texoma, and second, quantify the effects of environmental conditions on survival, growth, and reproduction of young of the year (YOY) juvenile zebra mussels. These biological responses directly influence population establishment success and invasive spread dynamics. Reproductive output of the zebra mussel population in Lake Texoma was significantly related to water temperature and lake elevation. Annual maximum larval (veliger) density decreased significantly indicating a population crash, which was likely caused by thermal stress and variability of lake elevation. In 2011, temperatures peaked at 34.3°C and lake elevation decreased to the lowest level recorded during the previous 18 years, which desiccated a substantial number of settled mussels in littoral zones. Estimated mean date of first spawn in Lake Texoma was observed approximately 1.5 months earlier than in Lake Erie, and peak veliger densities were observed two months earlier. Veligers were observed in the deepest oxygenated water after lake stratification. During a 69-day in situ experiment during summer in Lake Texoma, age-specific mortality of zebra mussels was generally high until temperatures decreased to approximately 28°C, which was observed after lake turnover in late summer. No study organism died after temperatures decreased to less than 26°C, which indicates individuals that survive high summer temperatures are likely to persist into autumn/winter. Shell length growth and soft tissue growth rates were related to temperature and chlorophyll-a concentration, respectively. Growth rates of study organisms were among the highest ever reported for D. polymorpha. Water temperature and body size influenced reproduction of YOY zebra mussels in Lake Texoma. Fecundity of females were positively related to temperature; however, sperm production was negatively related to temperature, which indicates males could be more sensitive to physiologically-stressful conditions than females and could perform better in cooler waters. YOY mussels spawned up to approximately 40,000 eggs and 3.47E+08 sperm after a single-summer growing season. Reproductive effort and reproductive mass were independent of sex. YOY individuals from each study site (n = 5) were able to spawn viable gametes capable of sperm binding and egg cleavage, which provides the first evidence that YOY zebra mussels can successfully reproduce. Individual mortality of zebra mussels will likely be high in warm waters and intermittent, extreme droughts, which are observed more frequently at lower latitudes, can significantly reduce population sizes. However, rapid growth and single-season maturation can decrease generation times and could facilitate establishment and spread of zebra mussels in warm-water environments in the southern United States.

Dealing with invasive alien species (IAS), have become a more common problem for themunicipalities of Sweden over the past years. IAS is one of the largest threats to biologicaldiversity and the spread of invasive alien plants is caused by transportation, travel, climatechanges but also infrastructure projects. Thus, the risk of spreading them must be dealt withearly in the progress of handling soil masses. This study examines if recommended routines(with the aim of reducing the risk of spreading invasive plants) are incorporated inmunicipalities and how well they function. It further examines if routines for invasive plantsare related to the size of the municipality, due to differences in economy and resources. Aform was sent to all 290 municipalities in Sweden and 132 answered. The results show thatmany of the recommended routines are not well incorporated across municipalities. Routineswith demands of knowledge about IAS to coworkers or entrepreneurs is less functioning thanroutines of intern information, such as where invasive plants are established on propertiesthat’s own by municipalities. Results show that available resources and economy due to sizeof the municipalities do not influence the level of incorporation of routines. It’s warranted formunicipalities to establish functioning routines within the organization to prevent increasingspread of invasive alien plants in an early stage. The issue should be addressed in decisionsmade by politicians to confirm the level of priority since the benefits of prevention is higherthan benefits of elimination and eradication.

The Runic scripture is very unique and complicated and has evolved for over centuries and resulted in unique Runic variants such as Gothic Runes, Anglo-Frisian and more. But where did Runes come from and how did they spread throughout Europe is what this paper will attempt to answer by going over multiple Runic objects as well as different historical literatures and databases in order to establish potential routes for which Runes could have spread through. Such as from Rhine to Northern Europe or from Germany to the rest of Northern Europe or Gaul to Northern Europe. However the people that spread the Runes are partially unknown with some suggesting that it was a group from a Germanic area that spread it, but no clear evidence appears until around 400 AD when a clear migration of people was visible in Frisia and England.

Som en följd av global uppvärmning blir det allt viktigare med resiliens mot klimatkrisens konsekvenser, däribland mer frekventa skogsbränder. Då våtmarker kan behålla vatten och ge resiliens mot torka och bränder är det intressant att undersöka relationen mellan våtmarker och skogsbränder. Syftet med detta arbete är att undersöka våtmarkers påverkan på skogsbränder i boreala skogsmiljöer, där frågeställningarna berör antändningsrisk, intensitet, brandskador, areell spridning och utdikning. Arbetet genomförs som litteraturstudie och GIS-analys med fokus på brandspridning. I GIS genomfördes först en multikriterieanalys och sedan en modellering av brandförlopp, i två områden i Hälsingland. Enligt analys och tolkning av resultat är fuktighet, grundvattennivå, vegetation, ytstruktur och storlek de viktigaste faktorerna i våtmarkers relation till skogsbränder. Sannolikhet för antändning, brandintensitet och brandskador minskar alla med ökad fuktighet, ökad grundvattennivå, gott om vitmossa och mindre av annan vegetation. Dessa faktorer gör även våtmarker till bättre brandbarriärer, speciellt i kombination med ökad storlek och heterogen ytstruktur. I motsats är våtmarker med lägre fuktighet och grundvattennivå, större bränsletillgång och träd sämre som barriärer mot skogsbrand och upplever intensivare bränder. Under extrem torka riskerar dock alla våtmarker, i olika utsträckning, att torka ut till den grad att bränder sprider sig över dem.GIS-analysen visar en koppling mellan sankmarker och områden med långsam brandspridning under normala förhållanden, och en stor lokal variation i förutsättningarna för brandspridning. Utdikning av våtmarker försämrar våtmarkernas resiliens mot skogsbränder, och skapar en risk för torvbränder, med allvarliga konsekvenser. En återvätning av utdikade våtmarker skulle förbättra deras brandresiliens. / As a result of global warming, it is ever more important with resilience towards the consequences of the climate crisis, including more frequent wildfires. Since wetlands can retain water and give resilience towards drought and fires, it is interesting to explore the relation between wetlands and wildfires. This study aims to research the influence of wetlands on wildfires in boreal forest environments, with research questions regarding risk of ignition, fire intensity, fire damage severity, areal spread and wetland drainage. The work consists of a literature review and GIS analysis focusing on fire spread. The GIS analysis is done through a multi-criteria analysis and afterwards a modeling of fire development, in two areas in Hälsingland, Sweden. According to analysis and interpretation of the result, the most important factors in the relation between wetlands and wildfires are moisture, water table level, vegetation, surface structure and wetland size. Probability of ignition, fire intensity and fire damage are all reduced with increased moisture, higher water table, plenty of sphagnum moss and less other vegetation. These factors also improve wetland efficiency as barriers against fire, especially in combination with increased size and a heterogeneous surface structure. On the contrary, wetlands with a lower moisture level and water table, larger fuel availability and trees function less efficiently as fire barriers and experience more intense fires. During extreme drought, however, all wetlands to a different extent risk drying out to the point where fire can spread over them. The GIS analysis displays a connection between fens and areas with slow fire propagation under normal conditions, as well as a large local variation in the factors influencing wildfire propagation. Wetland drainage deteriorates wetland resilience against wildfires, and creates a risk of peat fires, with severe consequences. Rewetting of drained wetlands would improve their fire resilience.

Background: With the global decline of honey bee populations, safeguarding these vital pollinators has become crucial. Varroa destructor mites are a primary threat, weakening bees and facilitating the spread of diseases, which can decimate colonies and disrupt ecosystems. This thesis investigates the application of a Wireless sensor network (WSN) for the monitoring and control of varroasis spread within bee colonies across large geographical areas. Objectives: The main objective of this research is to develop an integrated method that combines biological insights into varroasis with WSN functionalities for real-time disease monitoring and control. By doing so, the study aims to contribute to the development of a scalable and sustainable approach to apiculture and disease management. Methods: A multi-phase methodological approach was employed, encompassing the modelling of biological phenomena, formulation of WSN functionalities, and the design of a scalable WSN architecture. Simulation studies were conducted, followed by the development of a theoretical framework to support the practical application of the proposed WSN system. A key aspect of the methodology is the introduction of energy estimation models to evaluate the operational feasibility of the WSN. Results: The results indicate that the WSN is capable of dynamically adjusting its monitoring rate in response to changes in infection dynamics, effectively identifying and managing varroa mite populations. The system demonstrated adaptability to various infection rates, with the potential to improve the timely and targeted treatment of infested colonies. Energy consumption data further affirms the operational viability of the WSN. Conclusions: The study concludes that integrating WSNs with biological models is a viable solution for the real-time monitoring and management of varroasis. The proposed WSN system holds promise for enhancing the health and productivity of bee colonies on a broad scale, offering a novel contribution to the fields of apiculture and environmental monitoring.

This study examines asymmetric information content of REIT IPOs as compared to that of industrial IPOs matched by similar asset size, underwriter reputation ranking, and partial adjustment of the offer-price from the midpoint of the original file range. The asymmetric information level is proxied by the relative bid-ask spread (RELSPREAD), adverse selection component of Glosten and Harris (GH, 1988), and the adverse selection component of Lin, Sanger, and Booth (LSB, 1995). All three measures are estimated over 45- and 60-day windows. Using a sample of 78 equity REIT IPOs and 123 Industrial IPOs for the period of January 1, 1993 to December 31, 2007, the results indicate that REIT IPOs have less asymmetric information content as compared to mature industrial firms. All results control for leverage, beginning assets size, issue proceeds, underpricing, partial adjustment, number of IPOs within the same year, venture capital backing, underwriter reputation, average daily volume, average daily price, specialist’s inventory risk, and the turnover ratio. The results also control for the Nasdaq and NYSE rule change of minimum tick increments from 1/8th to 1/16th on June 2, 1997, and June 24, 1997, respectively. The findings provide strong support for the hypothesis that REIT IPOs have less asymmetric information content than non-REIT IPOs.

No description available.

No description available.

No description available.