The Tibbitt-to-Contwoyto Winter Ice Road (TCWR) is the sole overland route servicing diamond mines north of Yellowknife, Northwest Territories (NWT), Canada. The road is 568 km long, 85% of which extends over frozen lakes. As such, its operational season is highly dependent upon the length of the winter season. This was exemplified in 2006, when an El Niño event caused an unusually short ice road season and resulted in a costly reduction of shipments to the mines. For future use and development of the TCWR, a comprehensive understanding of past regional climate variability is required. This study is an integral component of a larger-scale study designed to develop a comprehensive database of high-resolution paleoclimate data for the NWT, using a variety of proxies. As part of the larger study, freeze cores were taken from numerous lakes along the TCWR and sliced at 1-mm intervals using a custom-designed sledge microtome. Bulk 13C and 15N isotope analysis was completed at preliminary 1-cm intervals through the cores of two lakes on opposite sides of the tree line. Results from this analysis show clear trends with distinct transitions in both cores, whose closely-matched timing suggests regional-scale climate events. These results indicate that the Early Holocene was warm and dry, with a sudden shift to wetter conditions around 7200-6900 cal yr BP. Another shift to cooler conditions occurred at 4000 cal yr BP, and a final transition to even cooler temperatures occurred around 755-715 cal yr BP, coinciding with the Little Ice Age. Additionally, a modern lake survey was completed using surface sediments of numerous lakes throughout the Arctic and Subarctic. This survey verifies the strong influence of boreal forest vs. tundra conditions in affecting various environmental properties within lakes, including carbon and nitrogen isotopes. Lastly, time-series analysis was completed on two sections of Danny’s Lake core at high resolution (up to 2 mm), in order to determine short-term climate cycles. These results highlight specific climate frequencies which may be related to the Pacific Decadal Oscillation. These results offer insight to short-term climate phenomena in the Northwest Territories which will allow future climate modellers to make more accurate predictions of future climate and its impact on the ice road.

Analysis of soil-derived DNA has been shown to minimize problems seen during traditional vegetation surveys, e.g. by matching the eDNA to a reference database for taxonomic identification rather than relying solely on taxonomic expertise. However, it has been debated to what extent and how accurately eDNA acts as a proxy for biodiversity. The reliability on eDNA and the awareness on influencing factors is also important for palaeoenvironmental reconstructions where above-ground vegetation cannot be used. This study aimed to investigate how well modern soil-derived eDNA reflects the contemporary vascular vegetation communities in a subarctic environment, and if the efficiency of the taxonomic identification differed between spatial scales. Near-surface soil samples at altitudinal gradients along numerous transects were collected in combination with vegetation surveys. The eDNA was amplified through metabarcoding using the P6 loop region of the chloroplast trnL intron, followed by a high-throughput sequencing. No difference in the number of identified taxa between eDNA and vegetation survey was seen at landscape scale. In contrast, the number of identified taxa was consistently higher in the vegetation survey at smaller spatial scales. The efficiency of identified taxa per scale remained stable for the vegetation survey, whereas for eDNA, a decreasing trend was seen. This study highlights the variations on taxa identification between both methods and which factors might cause it. Combining the methods allows for a more precise modern biodiversity estimation, as well as to minimize wrongful conclusions. This allows for a more accurate palaeoenvironmental reconstructions, which in turn can improve future species conservation decisions.

Long-term warming experiments in arctic tundra have resulted in reduced moss cover and increased vascular plant cover. As mosses have a major impact on microclimatic conditions, changes in community composition can potentially alter direct and indirect drivers of productivity and decomposition, which are low in arctic ecosystems. This can potentially change the carbon balance. Therefore, it is of importance to investigate how the effects of warming on ecosystem processes depend on the identity of the moss species dominating the vegetation. Furthermore, because subarctic climate is expected to get warmer and wetter, it is essential to examine how warming effects depend on variation in precipitation as well. Thus, Gross Primary Production (GPP) and Ecosystem Respiration (Reco) fluxes, moss growth, and decomposition rate, were measured in plot pairs along a natural precipitation gradient in subarctic tundra Sweden. Each pair was dominated by one of three common moss species (Hylocomium splendens, Pleurozium schreberi and Sphagnum spp.), and were subjected to moss removal and Open Top Chamber (OTC) warming treatment combinations. Moss growth measurements were taken as a measure of productivity and Tea Bag Index was used as a measure of decomposition rate. Warming effects on GPP depended on both species and precipitation; Hylocomium and Sphagnum had highest productivity in warmed high-precipitation plots, whereas the effect was negative in all cases for Pleurozium. No significant interactions were found for the other response variables, but there was a positive effect of warming on Reco across all treatments, as well as a negative effect on decomposition. Warming induced increases in GPP and respiration, and decrease in decomposition rate, could imply that the increase in CO2 emissions from arctic ecosystems will be smaller than predicted, as the sequestration of CO2 in that case would exceed what is being emitted. Still, it is a complex matter and therefore crucial to further investigate the role of moss species in relation to warming effects on ecosystem processes.

<p> The interaction of biological and physical processes has resulted in distinct morphological and biological zonation across the Subarctic macrotidal tidal flats at the head of Frobisher Bay. The tidal flats have been divided into six morphological zones which are closely related to the three biological communities found there. </p> <p> Faunal species of the Upper Flat inhabit the beach and fines flat morphological zones where ice action during breakup and freezeup has the greatest influence. Species inhabiting these zones are hardy, and freshwater tolerant. Many are highly motile and recolonize the area after ice breakup. </p> <p> The Middle Flat extends from 5.0 m ALLT to 2.2 m ALLT. It is inhabited by motile polychaetes at its upper end (bouldery flat >4.5 m ALLT). with more sedentary species appearing towards its lower end (very bouldery flat). Below 2.2 m ALLT, on the Lower graded flat, sedentary infauna such as Cyrtodaria kurriana, Mya truncata and sabellid polychaetes, dominate the substrate. </p> <p> The three major processes acting on the tidal flats are, in order of importance, tidal, ice and wave action. Exposure indices, generated from tidal data, reveal 2 critical tidal heights at around 4 m and 7.5 m ALLT, in Frobisher Bay. The boundary between motile and less motile fauna, and bouldery and very bouldery morphological zones, occurs around 4.0 m ALLT. Of the flora and fauna only Fucus evanescens is found beyond the 7.5 m ALLT limit. </p> / Thesis / Master of Science (MSc)

A sequence of burned surfaces aged 0, 1, 2, 24, and 80 years was investigated regarding changes in the spectral distribution of reflected light. Controls were introduced to isolate diurnal and seasonal effects. The results show gradually increasing reflectance with increasing age of burn. With the establishment of vegetation a new set of absorbtion and reflectance criteria are established substantially altering the spectral characteristics. The apparent effect of a mature forest canopy is ambiguous. Diffuse and overcast conditions reduce the reflectance for all surfaces. Further work is suggested to reinforce results for surfaces with low sampling replication. / Thesis / Bachelor of Science (BSc)

In the territory of the Gwich’in First Nation, in Canada’s Northwest Territories, environmental, sociocultural, and economic changes are affecting relationships between communities and the land and water. In this thesis, I used two research projects to explore the impacts of social-ecological change in Gwich’in territory by examining cumulative impacts in the cultural landscape, and determinants of access to fish and well-being. In the first part of my MA, I used spatial overlay analysis to quantify and map: 1) cultural feature intensity, 2) cumulative environmental disturbance, and 3) overlap between disturbances and cultural features. I also interviewed four regional cultural heritage experts, who contributed critical insights into representing Gwich’in cultural features. The first two analyses indicated that overlay methods can facilitate understandings of land use and cumulative impacts, illustrating Gwich’in territory as a cultural landscape encompassing widespread, dense cultural features and diffuse, lower intensity cumulative environmental impacts. The third analysis showed that overlaying cultural feature and disturbance data is a novel, straightforward step to better incorporating cultural impacts in cumulative impact assessments. Many of the changes I mapped are affecting fishing practices central to Gwich’in livelihoods. To better understand these changes, in the second part of my MA I explored the relationship between drivers of access to fish and well-being amidst social-ecological change, by interviewing 29 Gwich’in individuals. My interviews showed that socioeconomic and environmental barriers have decreased access to fish. However, access to fish remains critical and related to well-being, driven by various socioeconomic factors. Many of these factors are reflected in sharing networks and adaptive practices that are encompassed in ecological monitoring and land-based education. These factors may strengthen Gwich’in fishing livelihoods, and highlight the importance of programs like the Rat River Char Monitoring program, and land-based education like the Ganahghootr’onatan – Teetł’it Land Based Learning Project. / Graduate

<p>Att verka med ett militärt förband i subarktisk miljö är krävande då det alltid finns en naturlig fiende närvarande – den ständiga kylan. Det finns mycket skrivet om ledarskap, subarktisk miljö och Finska vinterkriget men jag har inte funnit något om ledarskapets betydelse i subarktisk miljö. Syftet med denna uppsats är att undersöka om utvecklande ledarskap är en applicerbar ledarstil i subarktisk miljö. Denna uppsats bygger på kvalitativ text analys med en analys av subarktisk miljö, utvecklande ledarskap samt om Finska vinterkriget 1939-1940. Resultatet i denna uppsats visar att utvecklande ledarskap är en bra ledarstil i subarktisk miljö, en miljö som kan beskrivas som en extrem miljö. Dock så skiftar de olika delarnas betydelse i utvecklande ledarskap beroende på vilket uppdrag som gruppen har samt i vilken situation som gruppen befinner sig i vid ett specifikt tillfälle.</p> / <p>To work with a military unit in the subarctic environment is demanding, and then there is always a natural enemy of the moment - the constant cold. There's a lot written about leadership, subarctic environment and the Finnish Winter War, but I have not seen anything on the leadership role in the subarctic environment. The purpose of this paper is to examine whether developing leadership is a leadership style in applicable subarctic environment. This essay is based on qualitative text analysis with an analysis of the subarctic environment, developing leadership and the Finnish Winter War of 1939-1940. The results in this paper show that developing leadership is a good leadership style in the subarctic environment, one environment that can be described as an extreme environment. However, as the shifting importance of different parts developing leadership, depending on the mission that the team has and in what situation the group is in at a specific time.</p>

Att verka med ett militärt förband i subarktisk miljö är krävande då det alltid finns en naturlig fiende närvarande – den ständiga kylan. Det finns mycket skrivet om ledarskap, subarktisk miljö och Finska vinterkriget men jag har inte funnit något om ledarskapets betydelse i subarktisk miljö. Syftet med denna uppsats är att undersöka om utvecklande ledarskap är en applicerbar ledarstil i subarktisk miljö. Denna uppsats bygger på kvalitativ text analys med en analys av subarktisk miljö, utvecklande ledarskap samt om Finska vinterkriget 1939-1940. Resultatet i denna uppsats visar att utvecklande ledarskap är en bra ledarstil i subarktisk miljö, en miljö som kan beskrivas som en extrem miljö. Dock så skiftar de olika delarnas betydelse i utvecklande ledarskap beroende på vilket uppdrag som gruppen har samt i vilken situation som gruppen befinner sig i vid ett specifikt tillfälle. / To work with a military unit in the subarctic environment is demanding, and then there is always a natural enemy of the moment - the constant cold. There's a lot written about leadership, subarctic environment and the Finnish Winter War, but I have not seen anything on the leadership role in the subarctic environment. The purpose of this paper is to examine whether developing leadership is a leadership style in applicable subarctic environment. This essay is based on qualitative text analysis with an analysis of the subarctic environment, developing leadership and the Finnish Winter War of 1939-1940. The results in this paper show that developing leadership is a good leadership style in the subarctic environment, one environment that can be described as an extreme environment. However, as the shifting importance of different parts developing leadership, depending on the mission that the team has and in what situation the group is in at a specific time.

Phosphorus is the main limiting nutrient for plant growth in large areas of the world and the availability of phosphorus to plants and microbes can be strongly affected by soil properties. Even though the phosphorus cycle has been studied extensively, much remains unknown about the key processes governing phosphorus availability in different environments. In this thesis the complex dynamics of soil phosphorus and its availability were studied by relating various phosphorus fractions and soil characteristics to microbial respiration kinetics. The soils used represent a range of aluminium, iron, carbon and total phosphorus content, and were located in four different biomes: subtropical forest, warm temperate forest, boreal forest and tundra. The results showed that NaOH extractable phosphorus, a fraction previously considered to be available to plants only over long time scales, can be accessed by microbes in days or weeks. Microbial phosphorus availability was not related to aluminium or iron content in any of the studied systems, not even in highly weathered soils with high aluminium and iron content. This is in contrast with other studies of soils with high sorption capacity and shows the variability of factors that govern phosphorus availability in different environments. In the boreal forest chronosequence, no difference could be seen with age in total phosphorus content or concentrations of occluded phosphorus forms. However, there were lower concentrations of labile phosphorus forms in older systems, which were correlated with a decrease in microbial respiration. This was most likely related to organic matter quality in the system, and not to geochemical factors. Phosphorus availability was linked to differences in topography (water regime) and vegetation in the tundra ecosystems. The results suggest that the availability of phosphorus, both for microbes and plants, was lower on the meadow vegetation sites compared to the two types of heath vegetation. Many factors are important for phosphorus availability in soils, but these results suggest that microbes can access less available phosphorus if not restricted by carbon, and this may be important in regard to forest management practices as well as effects of environmental change.

Net ecosystem carbon dioxide exchange (NEE) was measured using the eddy covariance (EC) technique at a wetland tundra-sedge fen near Churchill, Manitoba, Canada during two consecutive growing seasons (2007 and 2008). Mean daily NEE at the fen (DOY 157-254) was -3.5 (± 0.26 S.E.) g CO2 m-2 d-1 in 2007 and -4.6 (± 0.36) g CO2 m-2 d-1 in 2008. The fen was a net carbon dioxide (CO2) sink during both the 2007 and 2008 growing seasons of -343 (± 79) and -450 (± 87) g CO2 m-2, respectively. Mean air temperature during the summer (June 1-August 31) was about 1°C greater than the historical average (1971-2000) in 2007 and about 2°C greater in 2008. Growing season precipitation was 107.5 mm below normal in 2007 and 359.5 mm above normal in 2008. These data suggest that if future climate change brings warmer temperatures and near-to-above average precipitation maintaining the water table near the surface, similar subarctic ecosystems will experience increased gross ecosystem productivity enhancing CO2 sequestration during the growing season.