The Mountain Hemlock (MH) zone includes all subalpine forests along British Columbia’s coast. It occurs at elevations where most precipitation falls as snow and the growing season is less than 4 months long. The zone includes the continuous forest of the forested subzones and the tree islands of the parkland subzones (Figure 1). Old-growth stands are populated by mountain hemlock, Pacific silver fir, and Alaska yellow-cedar, and are among the least-disturbed ecosystems in the world. Canopy trees grow slowly and are commonly older than 600 years, while some Alaska yellow-cedars may be up to 2000 years old. Early regeneration failures followed slashburning and the planting of unsuitable species. Currently, the most successful and feasible option for reforesting cutovers is natural regeneration with a mix of the three main tree species, but uncertainties remain about the temporal and spatial pattern of regeneration, changes in species composition, and the time required for stand establishment after cutting. Our study addressed these concerns by examining regeneration patterns on 6 sites that were clearcut 11-12 years prior to sampling and left to regenerate naturally. The sites were located at the lower limits of the zone in the Tetrahedron Range, near Sechelt, at elevations from 1060-1100m.

The Mountain Hemlock (MH) zone includes all subalpine forests along British Columbia’s coast. It occurs at elevations where most precipitation falls as snow and the growing season is less than 4 months long. The zone includes the continuous forest of the forested subzones and the tree islands of the parkland subzones (Figure 1). Old-growth stands are populated by mountain hemlock, Pacific silver fir, and Alaska yellow-cedar, and are among the least-disturbed ecosystems in the world. Canopy trees grow slowly and are commonly older than 600 years, while some Alaska yellow-cedars may be up to 2000 years old. Understanding regeneration patterns in the MH zone has become increasingly important as logging continues towards higher elevations of the zone where snowpacks are deeper.

Non-forested ecosystems dominate high elevation sites in coastal British Columbia, yet there has never been a comprehensive classification or mapping of all high-elevation community types. The objective of this study is to collate and expand upon previous classifications, and thereby to increase our understanding of the habitats and composition of these plant communities.

This report expands and clarifies previous classifications of non-forested plant communities from upper subalpine and alpine locations in coastal British Columbia. A total of 80 plots (releves) sampled specifically for this study were added to 202 releves from published and unpublished studies conducted since 1963. We used tabular and multivariate methods to synthesize and classify plant communities according to the Braun-Blanquet approach. Plant communities were classified into 37 vegetation units (associations or subassociations) which served as the basis of the resulting hierarchical classification. We describe the habitat and species composition of these vegetation units and their relationship to units recogized elsewhere in the Pacific Northwest. We then present eight generalized habitat types which we propose as the basic units for future ecosystem mapping. Each of these habitat types includes a predictable mosaic of vegetation units whose pattern occurs at too fine a scale to map individually.

No description available.

Hantaviruses are the causative agents of hemorrhagic fever with renal syndrome (HFRS) in Eurasia, and of hantavirus cardiopulmonary syndrome (HCPS) in the Americas. Transmission to humans usually occurs by inhalation of aerosolized virus-contaminated rodent excreta. To date, human-to-human transmission has only been described for the Andes hantavirus. The mode of transmission of Andes hantavirus is not yet known, but transmission through saliva has been suggested. In Sweden, we have one hantavirus that is pathogenic to humans, Puumala virus (PUUV), which is endemic in Central and Northern Europe. It induces a relatively mild form of HFRS, also called nephropathia epidemica (NE). The rodent reservoir is the bank vole (Myodes glareolus). The mechanism behind the pathogenesis of hantavirus is complex and probably involves both virus-mediated and host-mediated mechanisms. The aim of this project was to investigate the transmission mechanisms and pathogenesis of hantavirus disease in humans. In our first study, we described the largest outbreak of PUUV so far in Sweden. We investigated factors that might be important for causing the outbreak, and suggested that a peak in the bank vole population together with concurrent extreme weather conditions most probably contributed to the outbreak. Our next studies concentrated on human-to-human transmission of hantaviruses. We found PUUV RNA in saliva from PUUV-infected patients, suggesting that there is PUUV in the saliva of infected humans, although no person-to person transmission appears to occur with PUUV.  In the studies that followed, we showed that human saliva and human salivary components could inhibit hantavirus replication. We also found PUUV-specific IgA in the saliva of PUUV-infected patients, which might prevent person-to-person transmission of the virus.  In the final study, we focused on the pathogenesis of NE. One hundred five patients were included in a prospective study.  They were divided into a group with mild disease and a group with moderate or severe disease. We found that the immune response had a dual role in disease development. It was partly responsible for development of severe disease, with significantly higher amounts of neutrophils in severely ill patients, but it was also protective against severe disease, because patients with mild disease had higher levels of PUUV-specific IgG. In conclusion, a peak in the bank vole population in combination with extreme weather will increase the risk of human infection, PUUV RNA is present in saliva, PUUV-specific IgA and salivary components inhibit person-to-person transmission of PUUV, and the immune response is important for the pathogenesis of PUUV and the severity of the disease. / Hantavirus är en grupp av virus som finns hos gnagare som bär på viruset utan att själva bli märkbart sjuka. Varje hantavirus har anpassat sig till sin egen art av gnagare som de infekterar (kallas virusets reservoar). Hantaviruset kan överföras till människor från gnagare och kallas då för en zoonos eftersom detsprids från djur till människa. I människa orsakar hantavirus blödarfeber med njurpåverkan i Eurasien och blödarfeber med med hjärt och lungpåverkan i Nord- och Sydamerika. I Sverige har vi bara ett hantavirus som är sjukdomsframkallande hos människor, Puumala-viruset som även finns i delar av övriga Europa. Det framkallar en relativt mild form av blödarfeber, som kallas sorkfeber eller Nephropathia epidemica. Puumala-virusets reservoar är skogssorken (Myodes glareolus). Människor smittas oftast av hantavirus när de andas in infekterat damm som innehåller utsöndringar (avföring, urin eller saliv) från gnagare som har torkat in och sedan blivit luftburet. Vad man vet hittills så finns det bara ett hantavirus som smittar från person till person, för övriga hantavirus är människan en ”dead end”. Det virus som kan smitta från person till person heter Andes hantavirus och finns i Sydamerika. Andes hantavirus har en mus som reservoar från vilken människor kan smittas, sedan har smittan i vissa fall förts vidare från människa till människa, som tur är har dessa utbrott gått att stoppa. Fastän utbrotten har varit små har många personer dött, eftersom dödligheten är så hög, ungefär 30-40% av de diagnostiserade fallen dör. Hur Andes hantavirus överförs från människa till människa är inte känt men överföring genom saliv har föreslagits. Hur viruset ger upphov till sjukdom hos människa är inte klarlagt. Studier talar för att mekanismen bakom sjukdomsutvecklingen (den så kallade patogenesen) hos hantavirusorsakade blödarfebrar är komplex. Sannolikt beror patogenesen både på egenskaper hos viruset och värden d.v.s. människan som är smittad av viruset. Vårt mål med detta projekt var att undersöka vad som hindrar överföring av Puumala hantavirus från människa till människa och att undersöka hur virusinfektionen påverkar sjukdomsutvecklingen hos människan. I vår första studie beskrev vi det största utbrottet av sorkfeber hittills i Sverige och vi undersökte faktorer som kan ha orsakat utbrottet. Vi föreslog att en topp i skogssorkpopulationen samtidigt med extremt varmt väder troligen bidrog till utbrottet. Utbrottet skedde i december och det extremt varma vädret medförde att snön smälte bort. Sorkarna bor vanligtvis under snön på vintern, vi tror att frånvaro av snötäcke fick sorkarna att söka sig till byggnader för att söka skydd och där kom i kontakt med människor. Våra efterföljande studier fokuserade på överföring av hantavirus från människa till människa. Vi hittade Puumala-virusets arvsmassa (RNA) i saliv från sorkfeberpatienter, vilket tyder på att det finns Puumala-virus i saliven hos infekterade människor, även om ingen överföring från person till person verkar inträffa. I efterföljande studier visade vi att mänsklig saliv och mänskliga salivkomponenter minskar hantavirus smittsamhet. Vi fann också Puumala-virusspecifika IgA-antikroppar i saliven från sorkfeberpatienter, vilket kan förhindra överföring från person till person. I den sista studien fokuserade vi på patogenesen hos människor efter hantavirusinfektion. 105 patienter ingick i en prospektiv studie och delades in i en grupp med mild sjukdom och en grupp med måttlig/svår sjukdom. Vi hittade en dubbel roll hos immunsvaret för sjukdomsutvecklingen. Immunsvaret var delvis ansvarig för utveckling av svår sjukdom med betydligt högre mängd neutrofiler hos svårt sjuka patienter, men det var också skyddande mot allvarlig sjukdom, eftersom patienter med en mild sjukdom hade högre nivåer av Puumalavirusspecifika IgG-antikroppar. Detta talar för att behandling med IgG-antikroppar specifikt riktade mot hantavirus skulle kunna vara effektiv hos hantavirusinfekterade patienter. Sammanfattningsvis; en topp i skogssorkspopulationen i kombination med extremt väder ökar risken för infektion hos människor; Puumala-virus arvsmassa (RNA) finns i saliv; Puumala-virusspecifika IgA-antikroppar och salivkomponenter hämmar överföring av Puumalavirus från person till person; immunsvaret är viktigt för Puumala-virus patogenes och sjukdomens svårighetsgrad.

This study is an interdisciplinary ecological study addressing the fine-scale relationships between plants, invertebrates and the environment in an alpine ecosystem. Alpine environments are marked by steep environmental gradients and complex habitat mosaics at various spatial scales. Regular forming periglacial patterned ground landforms on the Old Man Range, Central Otago, South Island, New Zealand present an ideal medium for studying plant-invertebrate-environment relationships due to their partitioning of the landscape into discrete units of contrasting environmental conditions, and the existence of some baseline knowledge of the soil, microclimate, vegetation and flora. The study was conducted in three types of patterned ground (hummocks, stripes and solifluction terraces) on the Old Man Range. Each component of the study was sampled at the same spatial scale for comparison. Temperature was recorded in the soil and ground surface from April 2001 to March 2004 in microtopographic subunits (microsites) of each patterned ground landform. Plant species cover was sampled within each microsite; invertebrates were sampled from soil cores taken from the same locations as plant samples in April 2001 and September 2001. The two sampling occasions coincided with autumn before the soil freezes, and winter when maximum freezing was expected. Fine-scale changes in the topographic relief of the patterned ground led to notable differences in the timing and duration of snow. The steepest environmental gradients existed during periods of uneven snow distribution. The soil in exposed or south-facing microsites froze first, beginning in May, and typically froze to more than 40cm depth. Least exposed microsites rarely froze. Within the microtopography, patterns of freezing at specific locations were consistent between years with only minor differences in the timing or depths of freezing; however, notable variation in freezing existed between similar microsites. Within the microtopography, different assemblages of organisms were associated with different microsites. In total, 84 plant and lichen species were recorded, grouping into six community types. Species composition was best explained by growing degree-days, freeze-thaw cycles, time frozen and snow-free days; species diversity and richness increased with increasing environmental stress as indicated by freeze-thaw cycles, time frozen and exposure. In total 20,494 invertebrates, representing four Phyla, 12 Classes, 23 Orders and 295 morpho-taxa were collected from 0.17m� of soil. Acari, Collembola and Pseudococcidae were the most abundant invertebrates. Over 95% of the invertebrates were found in the plant material and first 10cm depth of soil. Few significant relationships were found between diversity, richness or abundance of invertebrate taxa and the microsites; however, multivariate analyses identified distinct invertebrate assemblages based on abundance. Invertebrate composition was best explained by recent low temperature and moisture, particularly in winter; however, plant composition also explained invertebrate composition, but more so in autumn. This research has shown that organisms in the alpine environment of the Old Man Range are sensitive to fine-scale changes in their environment. These results have implications as to how historical changes to the ecosystem may have had long-lasting influences on the biota, as well as how a currently changing climate may have further impacts on the composition and distribution of organisms.

Figuring Space; considering the figure in the construction of space in materialist film is an analysis of film space that uses either the image of a figure or the actual figure of the viewer in its construction. The thesis focuses on particular screen works of William Raban, Guy Sherwin, Malcolm Le Grice, Chris Welsby, Nicky Hamlyn, Peter Gidal (all members of the London Filmmakers’ Cooperative) and the Canadian artist Michael Snow. It discusses the works in relation to the basic materials of time, light and sound found in film and video. The thesis looks at the way the film frame was implemented in the work of these artists to challenge preconceived notions of film space. It also highlights the uncertainty of spatial relativity within the screen image once the techniques imposed by the artist undermine previous determinations of positions in space. The frame provides necessary elements with which a reading of a pictorial space can be made. In addition, with some of the works discussed, the frame defines an exterior screen space that at times questions the boundaries between on-screen and off-screen, and fictive space and real space. While in other works that are addressed, binaries exist within which the boundaries of a picture plane are utilized to determine an object’s spatial relativity, which in turn questions the relativity of those boundaries that determine it. The frame that previously confirmed the illusions of space within the pictorial plane could no longer be prescribed as definitive. Calculations of the film space would become dependent upon a point of origin that is situated within actual time and space at the position of the viewer. The figure of paramount importance, when considering the constructs of space within materialist film, is that of the viewer

Cette thèse a pour objectif principal de contribuer à la compréhension des facteurs environnementaux agissant sur la diversité et la productivité des communautés végétales alpine, et dans un deuxième temps de mettre en évidence des changements récents dans la structure de la végétation dans un contexte tempéré alpin, les Alpes françaises. L’approche adoptée se base sur des méthodes issues de la télédétection et également de l’écologie végétale, en combinant des relevés de végétation avec les données de climat de l’imagerie à haute résolution. Dans le premier chapitre, je démontre l’intérêt de quantifier la durée d’enneigement afin de pouvoir prédire les patrons de diversité taxonomique et fonctionnelle, en montrant aussi que la modélisation spatiale de la productivité primaire reste un défi important dans le contexte des paysages alpins. Dans le deuxième chapitre, je teste l’utilité de l’imagerie satellitaire pour quantifier les conditions environnementales au niveau des communautés végétales, et je mets en évidence que l’habitat des communautés dominantes peut être différencié à l’échelle régionale par la date de déneigement et le pic en productivité. J’essaie également de voir si la diversité fonctionnelle influe sur la réponse NDVI dans le cadre de trois années de durée d’enneigement contrastées. Le troisième chapitre marque un changement d’approche, dans lequel je passe à l’analyse de la dynamique observée de la végétation pendant les dernières décennies dans deux sites : la Réserve Naturelle des Hauts Plateaux du Vercors (RNHPV) et le Parc National des Ecrins (PNE). L’analyse diachronique de l’écotone forêt-prairie dans la RNHPV montre une forte expansion de la forêt à Pinus uncinata pendant les soixante dernières années, en réponse à un réchauffement global et également des changements spatio-temporels dans les usages des terres en lien avec le pâturage. Dans la deuxième partie, je montre qu’avec les satellites on observe une tendance de verdissement à l’échelle du PNE pendant les dernières décennies. Je propose qu’une réduction dans la durée d’enneigement et un réchauffement depuis les années 1980s ont contribué à une augmentation de la productivité des canopées dans des contextes alpins de haute altitude, et ceci indépendamment des effets d’utilisation des terres. Pris ensemble, au lieu d’avancer un aspect précis de l’écologie alpine, mon travail sert à compléter nos connaissances du fonctionnement des communautés végétales alpines et à confirmer certaines hypothèses basées sur l’observation terrain avec des analyses spatiales robustes. / The central aim of this thesis is to contribute to current understanding of environmental drivers of plant diversity and productivity as well as of recent changes in vegetation structure in a temperate alpine context, the French Alps. My approach draws on methods from remote sensing and plant ecology by combining plot-based measures of plant diversity and climate data with high-resolution imagery. Chapter I demonstrates the importance of quantifying snow cover duration for predicting patterns of plant taxonomic and functional diversity, and also highlights the ongoing challenge of modeling spatial gross primary productivity dynamics in alpine landscapes. In Chapter II, I explore the utility of satellite imagery for quantifying environmental conditions experienced by alpine plant communities, and further show how metrics of snow cover duration and peak productivity can be used to differentiate habitat for dominant alpine plant communities. I also explore how functional diversity mediates NDVI responses to highly contrasting snow years. Chapter III provides new evidence of recent shifts occurring in high-elevation plant communities in the French Alps in response to climate and land-use change. Analysis of the forest-grassland ecotone in the Vercors Regional Park shows a strong dynamic of forest expansion in response to overall climate warming and local shifts in grazing-related land-use practices, which supports findings from other studies conducted elsewhere in the Alps and Pyrenees. In the second part of Chapter III, for the first time I present evidence of greening dynamics in a protected area of the French Alps, the Ecrins National Park. I propose that a decrease in snow cover duration and pronounced warming occurring in the 1980s likely contributed to increased canopy productivity in high alpine contexts, and are driving long-term greening in the absence of land-use change. Taken collectively, rather than pushing a specific aspect alpine ecology forward, my work helps to fill out our working knowledge of alpine plant communities and serves to solidify a number of field-based observations by carrying out robust spatial analyses.

Les extrêmes neigeux sont parmi les risques naturels les plus dangereux dans les régions montagneuses. Les processus max-stables, qui relient statistique des valeurs extrêmes et géostatistique, offrent un cadre approprié pour les étudier. Deux questions importantes concernant la dépendance spatiale des extrêmes sont traitées dans cette thèse à travers les cas des chutes et des hauteurs de neige dans les Alpes françaises : la sélection de modèle et la non-stationnarité temporelle. Nous utilisons pour cela deux jeux de données de maxima hivernaux de chutes de neige (90 stations de 1958 à 2013) et de hauteurs de neige (82 stations de 1970 à 2013). Nous décrivons d'abord une procédure de validation-croisée appropriée pour évaluer les capacités des processus max-stables à capturer la structure de dépendance des extrêmes spatiaux. Nous mettons en exergue trois processus max-stables pour leur aptitude à modéliser la dépendance spatiale des chutes de neige extrêmes : les processus de Brown-Resnick, géométrique gaussien et extrémal-t. Les performances de ces trois modèles sont extrêmement similaires, quel que soit le nombre de stations ou d'années. Ensuite, nous présentons une approche par fenêtre glissante pour évaluer l'évolution temporelle de la dépendance des extrêmes spatiaux. Nous montrons ainsi que les chutes de neige extrêmes ont tendance à être de moins en moins dépendantes spatialement. Nous montrons que cela est dû à une augmentation de la température provoquant une baisse du ratio neige/pluie. Il existe aussi un effet d'intensité avec des extrêmes moins dépendants à cause d'une baisse du cumul hivernal de chutes de neige. Enfin, nous présentons la première utilisation de processus max-stables avec des tendances temporelles dans la structure de dépendance spatiale. Cette approche est appliquée aux maxima de hauteurs de neige modélisés par un processus de Brown-Resnick. Nous montrons que leur dépendance spatiale est impactée par le changement climatique d'une manière similaire que celle des chutes de neige extrêmes. / Extreme snowfall and extreme snow depths are among the most dangerous hazards in the mountainous regions. Max-stable processes, which connect extreme value statistics and geostatistics by modeling the spatial dependence of extremes, offer a suitable framework to deal with. Two challenging issues concerning spatial dependence of extremes are broached in this thesis through the examples of snowfall and snow depths in the French Alps: model selection and temporal nonstationarity. We process two winter maxima data sets of 3-day snowfall (90 stations from 1958 to 2013) and snow depths (82 stations from 1970 to 2013). First, we introduce a leave-two-out cross-validation procedure appropriate for evaluating the predictive ability of max-stable processes to model the dependence structure of spatial extremes. We compare five of the most commonly used max-stable processes, using as a case study the snowfall maxima data set. This approach allows us to show that the extremal-t, geometric Gaussian and Brown-Resnick processes are able to represent as well the structure of dependence of the data, regardless of the number of stations or years. Then, we show, using a data-based approach allowing to make minimal modeling assumptions, that snowfall extremes tended to become less spatially dependent over time, with the dependence range reduced roughly by half during the study period. We demonstrate that this is attributable at first to the increase in temperature and its major control on the snow/rain partitioning. A magnitude effect, with less dependent extremes due to a decrease in winter cumulated snowfall, also exists. Finally, we tackle the first-ever use of max-stable processes with temporal trends in the spatial dependence structure. This approach is applied to snow depth winter maxima modeled by a Brown-Resnick process. We show that the spatial dependence of extreme snow depths is impacted by climate change in a similar way to that has been observed for extreme snowfall.