Dissertations / Theses on the topic 'Rares Borlea'

This thesis is concerned with the expression of relatively long-timescale growth forcing in tree-ring chronologies. The operation of different standardisation techniques, used in dendroclimatology to remove internal, non-climate related growth trends in measured series of ring-widths, is explored with an emphasis on the efficiency of the Regional Curve Standardisation (RCS) technique. The approach adopted here makes extensive use of concepts taken from tree-growth models and is based on the assumption that common external growth forcing operates through its influence on photosynthesis. A definition, of the growth rate of trees in terms of the carbon production by unit foliage, is the rationale that underlies this work and leads to the use of a multiplicative model for processing individual tree and chronology indices. The presence of a “common signal” in series of tree measures can lead to the distortion of the shape of detrending curves and a problem with bias in chronologies. Problems of the RCS technique are identified which are associated with tree age and diameter-related bias, arising from the use of ring-width to establish tree growth rates, regardless of tree diameter. These problems are manifest as “end effects” in chronology development and are most significant in the most recent century. Alternative, significant modifications of the RCS approach are proposed: the Multiple RCS (MRCS) and the Size-Adjusted RCS (SARCS) methods which greatly mitigate these problems. These are made possible by the introduction of two new concepts in dendroclimatology: the “best fit means” method and the use of “signal-free measures”. The concept of the mechanical strength of trees is used to simulate tree growth from series of ring-width measures and a “process based standardisation” (PBS) model is developed. The PBS model is tested and shown to be a feasible alternative to existing standardisation techniques.

This thesis is about a workforce in the midst of regional economic fragmentation. It is an ethnographic study of a commercial farm on South Africa’s border with Zimbabwe, where farmer-landowners are white Afrikaners, and workers black and overwhelmingly Zimbabwean. Fleeing the hyperinflation and violent state oppression of the ‘Zimbabwean crisis’, farm workers encounter South Africa’s neoliberal restructuring, contraction of labour-intensive industry, and land reform. Economic informalisation in both countries – a shift to short-term strategies of ‘making do’ – seems to hail the disappearance of southern Africa’s longer-term patterns of racialised migrant labour systems. This thesis, however, argues for a labour relations or ‘productivist’ perspective on current trends. Agricultural workforces on the Zimbabwean-South African border, with their established forms of everyday organisation and on-site residence, profoundly shape the local setting. Their highly structured arrangements bear the mark of the region’s labour history, yet also reflect the forms of fragmentation currently characterising southern Africa. The thesis begins by exploring white border farmers’ self-understandings through their notions of success. It then offers a wider historical account of the border’s settler capitalists, their struggles for control of land and labour, and the role played by their enterprises as hubs of settlement. Focusing on one border farm today, the study turns to the black workforce itself. It investigates how permanent workers consolidate their powerful positions in diverse areas of life, blurring spheres of work and non-work; how seasonal workers, many displaced from Zimbabwe, with diverse socio-economic backgrounds, engage with the hierarchies built around their permanent counterparts; and how, in the midst of all this, senior black workers struggle over status by means of contrasting models of authority, pitting established paternalism against idioms of corporate management. Together, these perspectives reveal how a workforce’s internal arrangements both reflect and refract the wider dynamics of the border and of Zimbabwean displacement. The thesis finally develops this central theme by addressing the position of farm work in a wider economy of trade and services on the farms and across the border. Based on ethnographic fieldwork on one border farm, and in the border area more generally (November 2006-April 2008), and supported by archival research, this thesis contributes to the anthropology of work. It shows how workplace dynamics act as a prism, refracting the meanings of work, movement and upheaval in an era of informalisation, and embed displaced migrant workers in dense webs of dependence and obligation.

Master of Arts
Department of Economics
Tracy Turner
I analyze the impact of differences in the cigarette excise tax rates of bordering states on the price elasticity of demand for cigarettes in the home state. Using unique county-level data on the sales tax revenues collected from Kansas tobacco sellers by industry type provided by the Kansas Department of Revenue, as well as data on cigarette excise tax rates, distance to Kansas’ borders, and the combined state and county sales tax rate, I examine the determinants of tobacco sales tax revenue using a fixed effects model. The analysis allows me to infer cigarette demand effects, and I find that the price elasticity of demand for cigarettes in Kansas becomes significantly more elastic closer to a low tax border. Model estimates for gas stations with convenience stores and tobacco retailers suggest that a Kansas cigarette excise tax decrease would result in more sales tax revenue on average for counties within 50 miles of a low tax Kansas border, ceteris paribus.

The subarctic boreal forest biome is predicted to experience higher magnitudes of warming than other biomes due to climate change. The effects of this warming will be pronounced in areas underlain by discontinuous permafrost where melting permafrost and distinct changes in vegetation patterns are expected. To better understand rates of hillslope diffusion in the boreal forest I have used a geomorphic process modeling approach, using data from a sequence of Quaternary fluvial terraces located in the Nenana River valley of central Alaska. I hypothesized that diffusion rates here would be slower when compared to the mid-latitudes, and faster on north versus south-facing slopes. Calculated diffusion rates do support the hypothesis as they fall on the lower end of the global spectrum of documented hillslope diffusion rates. However, a significant difference in diffusion rates is not seen between the predominantly northeast and southwest facing slopes used in this study.

Soils of Northern Hemisphere forests contain a large part of the global terrestrial carbon (C) pool. Even small changes in this pool can have large impact on atmospheric [CO2] and the global climate. Soil respiration is the largest terrestrial C flux to the atmosphere and can be divided into autotrophic (from roots, mycorrhizal hyphae and associated microbes) and heterotrophic (from decomposers of organic material) respiration. It is therefore crucial to establish how the two components will respond to changing environmental factors. In this thesis I studied the effect of elevated atmospheric [CO2] (+340 ppm, 13C-depleted) and elevated air temperature (2.8-3.5 oC) on soil respiration in a whole-tree chamber (WTC) experiment conducted in a boreal Norway spruce forest. In another spruce forest I used multivariate modelling to establish the link between day-to-day variations in soil respiration rates and its δ13C, and above and below ground abiotic conditions. In both forests, variation in δ13C was used as a marker for autotrophic respiration. A trenching experiment was conducted in the latter forest in order to separate the two components of soil respiration. The potential problems associated with the trenching, increased root decomposition and changed soil moisture conditions were handled by empirical modelling. The WTC experiment showed that elevated [CO2] but not temperature resulted in 48 to 62% increased soil respiration rates. The CO2-induced increase was in absolute numbers relatively insensitive to seasonal changes in soil temperature and data on δ13C suggest it mostly resulted from increased autotrophic respiration. From the multivariate modelling we observed a strong link between weather (air temperature and vapour pressure deficit) and the day-to-day variation of soil respiration rate and its δ13C. However, the tightness of the link was dependent on good weather for up to a week before the respiration sampling. Changes in soil respiration rates showed a lag to weather conditions of 2-4 days, which was 1-3 days shorter than for the δ13C signal. We hypothesised to be due to pressure concentration waves moving in the phloem at higher rates than the solute itself (i.e., the δ13C–label). Results from the empirical modelling in the trenching experiment show that autotrophic respiration contributed to about 50% of total soil respiration, had a great day-to-day variation and was correlated to total soil respiration while not to soil temperature or soil moisture. Over the first five months after the trenching, an estimated 45% of respiration from the trenched plots was an artefact of the treatment. Of this, 29% was a water difference effect and 16% resulted from root decomposition. In conclusion, elevated [CO2] caused an increased C flux to the roots but this C was rapidly respired and has probably not caused changes in the C stored in root biomass or in soil organic matter in this N-limited forest. Autotrophic respiration seems to be strongly influenced by the availability of newly produced substrates and rather insensitive to changes in soil temperature. Root trenching artefacts can be compensated for by empirical modelling, an alternative to the sequential root harvesting technique.

Soils of Northern Hemisphere forests contain a large part of the global terrestrial carbon (C) pool. Even small changes in this pool can have large impact on atmospheric [CO2] and the global climate. Soil respiration is the largest terrestrial C flux to the atmosphere and can be divided into autotrophic (from roots, mycorrhizal hyphae and associated microbes) and heterotrophic (from decomposers of organic material) respiration. It is therefore crucial to establish how the two components will respond to changing environmental factors. In this thesis I studied the effect of elevated atmospheric [CO2] (+340 ppm, ¹³C-depleted) and elevated air temperature (2.8-3.5 oC) on soil respiration in a whole-tree chamber (WTC) experiment conducted in a boreal Norway spruce forest. In another spruce forest I used multivariate modelling to establish the link between day-to-day variations in soil respiration rates and its δ¹³C, and above and below ground abiotic conditions. In both forests, variation in δ¹³C was used as a marker for autotrophic respiration. A trenching experiment was conducted in the latter forest in order to separate the two components of soil respiration. The potential problems associated with the trenching, increased root decomposition and changed soil moisture conditions were handled by empirical modelling. The WTC experiment showed that elevated [CO2] but not temperature resulted in 48 to 62% increased soil respiration rates. The CO2-induced increase was in absolute numbers relatively insensitive to seasonal changes in soil temperature and data on δ¹³C suggest it mostly resulted from increased autotrophic respiration. From the multivariate modelling we observed a strong link between weather (air temperature and vapour pressure deficit) and the day-to-day variation of soil respiration rate and its δ¹³C. However, the tightness of the link was dependent on good weather for up to a week before the respiration sampling. Changes in soil respiration rates showed a lag to weather conditions of 2-4 days, which was 1-3 days shorter than for the δ¹³C signal. We hypothesised to be due to pressure concentration waves moving in the phloem at higher rates than the solute itself (i.e., the δ¹³C–label). Results from the empirical modelling in the trenching experiment show that autotrophic respiration contributed to about 50% of total soil respiration, had a great day-to-day variation and was correlated to total soil respiration while not to soil temperature or soil moisture. Over the first five months after the trenching, an estimated 45% of respiration from the trenched plots was an artefact of the treatment. Of this, 29% was a water difference effect and 16% resulted from root decomposition. In conclusion, elevated [CO2] caused an increased C flux to the roots but this C was rapidly respired and has probably not caused changes in the C stored in root biomass or in soil organic matter in this N-limited forest. Autotrophic respiration seems to be strongly influenced by the availability of newly produced substrates and rather insensitive to changes in soil temperature. Root trenching artefacts can be compensated for by empirical modelling, an alternative to the sequential root harvesting technique.

Dans cette thèse, nous nous intéressons aux propriétés statistiques des systèmes dynamiques aléatoires et non-autonomes. Dans le premier chapitre, consacré aux systèmes aléatoires, nous établissons un cadre fonctionnel abstrait, couvrant une large classe de systèmes dilatants en dimension 1 et supérieure, permettant de démontrer de nombreux théorèmes limites annealed. Nous donnons aussi une condition nécessaire et suffisante pour que la version quenched du théorème de la limite centrale soit valide en dimension 1. Dans le chapitre deux, après avoir introduit la notion de système non-autonome, nous étudions un système composé d'applications en dimension 1 ayant un point fixe neutre commun, et nous montrons que celui-ci admet une vitesse de perte de mémoire polynomiale. Le chapitre trois est consacré aux inégalités de concentration. Nous établissons de telles inégalités pour des systèmes dynamiques aléatoires et non-autonomes, et nous étudions diverses applications. Dans le chapitre quatre, nous nous intéressons aux lemmes dynamiques de Borel-Cantelli pour l'induction de Rauzy-Veech-Zorich, et présentons quelques résultats liés aux statistiques de récurrence pour cette application
The first chapter, devoted to random systems, we establish an abstract functional framework, including a large class of expanding systems in dimension 1 and higher, under which we can prove annealed limit theorems. We also give a necessary and sufficient condition for the quenched central limit theorem to hold in dimension 1. In chapter 2, after an introduction to the notion of non-autonomous system, we study an example consisting of a family of maps of the unit interval with a common neutral fixed point, and we show that this system admits a polynomial loss of memory. The chapter 3 is devoted to concentration inequalities. We establish such inequalities for random and non-autonomous dynamical systems in dimension 1, and we study some of their applications. In chapter 4, we study dynamical Borel-Cantelli lemmas for the Rauzy-Veech-Zorich induction, and we present some results concerning statistics of recurrence for this map

Les poussières atmosphériques naturelles jouent un rôle complexe dans le système climatique global étant à la fois un facteur affectant le climat et variant en fonction de ce dernier. Notre compréhension des différentes interactions entre les poussières atmosphériques et le climat est limitée par l’importante variabilité spatiale et temporelle des celles-ci. À l’aide de tourbières ombrotrophes, la variabilité spatiale et temporelle des dépôts de poussières atmosphériques holocènes au Québec boréal fut caractérisée en lien avec les fluctuations climatiques. Les flux de poussières atmosphériques furent reconstruits à l’aide des concentrations en terres rares. Les isotopes du Nd et Pb en combinaison avec les terres rares ont été utilisés afin de déterminer la source des particules déposées dans les tourbières. Afin d’évaluer les liens entre les flux de poussières et la variabilité climatique, les changements temporels dans les flux de poussières et l’isotopie du Nd furent comparés à la taille des particules déposée et des reconstitutions écohydrologiques basées sur l’analyse des macrorestes végétaux et des thécamoebiens. Dans les deux premiers volets de l’étude, les flux de poussières atmosphériques furent reconstruits dans deux tourbières de la Côte-Nord alors que les particules déposées dans celles-ci furent caractérisées à l’aide des concentrations des terres rares (REE), des isotopes du néodyme et du plomb ainsi que la granulométrie. Les deux profils présentent des valeurs de Nd similaires, ce qui s’explique soit par une source commune des poussières atmosphériques ou encore des sources distinctes, mais possédant des valeurs de Nd similaires dans les deux régions. Les deux sites étudiés montrent des tendances différentes dans les flux de poussières. La tourbière IDH montre peu de variations dans les flux de poussières, ce qui s’explique en partie par l’emplacement du site d’étude, qui prévient les apports de poussières atmosphérique. La tourbière Baie quant à elle, montre deux périodes de flux de poussières plus élevés soit 1700-1000 et 650-100 cal a BP correspondant avec des périodes de refroidissement du climat documentées. Les REE, le Nd et les tailles de particules suggèrent qu’au cours des 2000 dernières années, la tourbières de Baie a reçu une proportion accrue de poussières atmosphériques provenant de sources locales. Ces deux périodes ont été identifiées comme des épisodes d’instabilité climatique en réponse à une instabilité hydroclimatique régionale et une plus grande variabilité des températures (principalement contrôlée par l’activité solaire). Un changement du régime des vents dans la région a aussi probablement influencé ces les variations observées. Dans le troisième chapitre, les mêmes analyses furent réalisées sur des carottes de tourbe d’une tourbières de la Baie James, La Grande 2 (LG2). Des apports accrus de poussières furent observés lors de différentes période : 4000 à 3000, 2600 à 2000, 1600 à 1000, 800 à 650 cal a BP et de 1960 à 1990AD. Au moins trois sources distinctes constituent les apports de poussières dans le temps: les sédiments marins à la base de la tourbières, la moraine de Sakami, deux sources locales, ainsi qu’une source probablement plus régionale dont l’origine est non-identifiée. La période allant de 7000 à 4100 cal a BP montre des valeurs près des sources locales (Nd : -36 à -29). Une augmentation graduelle des valeurs de Nd à partir de 4100 cal a BP suggère une diminution des apports locaux de poussière à la faveur d’une source non identifiée. La majorité des périodes d’apports accrus de poussières identifiées correspondent à des périodes documentées comme étant froides et sèches probablement lié à des intrusions de masses d’air arctiques. La présence de certains de ces pics de poussières lors de minimums solaires suggère que la variabilité solaire joue aussi un rôle dans la variabilité climatique de la région
Mineral dust plays an important role in the global climate system having effects on the radiation budget and the chemical composition of the atmosphere. Our understanding of the exact role of dust in the Earth’s climate system is still poorly constrained mostly due to a lack of data reflecting the high spatial and temporal variability of dust. Using peat bogs, spatial and temporal variability of Holocene dust deposition in boreal Quebec was investigated in relation to climate fluctuations. Dust fluxes were reconstructed using rare earth elements (REE) concentrations in bulk peat, while Nd and Pb isotopes in combination with REE were used to identify the source of dust particles deposited into these bogs. In order to evaluate the relationship between dust fluxes and climate variability, temporal changes in dust flux, and Nd isotopes were compared to dust grain size and ecohydrological reconstructions derived from testate amoebae and plant macrofossils. In two peat bogs from the North Shore region of the St. Lawrence Estuary (Baie bog) and Gulf (IDH bog), atmospheric dust fluxes were reconstructed using REE concentration while the geochemical composition of deposited dust was characterized using Nd and Pb isotopes combined with REE and grain size. Both peat bogs present similar Nd values, which suggests either a common source or sources with similar signatures in both regions. In terms of dust flux, the two study sites display distinct tendencies. IDH bog show few variations in dust flux, which can be explained by its geographical setting, where a tree fringe and higher altitude likely partially prevent dust from reaching the peat bog. Two dust events were recorded in the Baie bog from 1750 to 1000 cal BP and 600 to 100 cal BP and correspond to documented cold periods. These two periods have been found to occur at the same time as periods of high variability in the macrofossil record (i.e. successive layers dominated by Sphagnum or Ericaceae). REE elements, Nd and grain-size distribution suggest that, over the last 2000 years, the Baie bog received more local dust. The two periods were identified as periods of increased local storminess in response to regional hydroclimatic instability and temperature variations mainly controlled by solar activity. These episodes of climatic instability could also have been caused by changes in the wind regime. The same set of analyses were performed in a third peatland located in the James Bay region, the La Grande 2 bog (LG2). Increases in dust flux were reconstructed from 4000-3000, 2600-2000, 1600-1000, 800-650 cal BP and from 1960-1990AD. The Nd values show a large variability from -37 to -12, identifying a least three sources: local marine sediment, the Sakami moraine and another unidentified source likely from a more regional origin. Between 7000 and 4100 cal BP, Nd values resemble those localsources (-36 to -29). A gradual increase in Nd signature is observed from 4100 to 1500 cal BP suggesting a decreasing influence of local sources in favor of a yet unidentified source. The occurrence of increased dust deposition during cold periods in two of the three studied bogs suggests that dust fluxes can be used as an indicator of cold and dry climatic conditions in boreal Quebec. In northeastern Canada, these cold and dry conditions are usually the results of the intrusion of Arctic air masses. The exact mechanism controlling these incursion is yet unknown, but the similar timing of solar minima and dust peaks suggest that solar irradiance may also have played a role. The fact that both Baie and LG2 sites display similar tendencies during the last 2000 years reveals that both regions were likely controlled by the same climatic processes

Specimens of 6 species of threatened, vulnerable, and endangered turtles (Cuora amboinensis, Cyclemys dentata, Heosemys grandis, Orlitia borneensis, Pyxidea mouhotii, and Siebenrockiella crassicollis) belonging to family Bataguridae, were confiscated in Hong Kong, China on 11 December 2001 by international authorities. Endohelminth studies on these turtle species are scarce, and this study provided a rare opportunity to examine a limited number of specimens for endohelminths. Ten different parasite species were collected and there were 16 new host records. This is the first record of a parasite from P. mouhotii. The parasite prevalences found in this study provide a basis for a better understanding of the phylogenetic relationships of the family Bataguridae to other families, especially Testudinidae. Based on known life cycles, parasites found provided an indication of food preferences of these 6 turtle species that support previous studies of the turtles' feeding habits. However, the results of the parasite survey from O. borneensis provided additional feeding habit information. The list of endohelminths herein is intended to provide a foundation for future parasite studies of the 6 species of Asian turtles.

Cette thèse s'inscrit dans le domaine de l'apprentissage statistique. Le cadre principal est celui de la prévision de suites déterministes arbitraires (ou suites individuelles), qui recouvre des problèmes d'apprentissage séquentiel où l'on ne peut ou ne veut pas faire d'hypothèses de stochasticité sur la suite des données à prévoir. Cela conduit à des méthodes très robustes. Dans ces travaux, on étudie quelques liens étroits entre la théorie de la prévision de suites individuelles et le cadre statistique classique, notamment le modèle de régression avec design aléatoire ou fixe, où les données sont modélisées de façon stochastique. Les apports entre ces deux cadres sont mutuels : certaines méthodes statistiques peuvent être adaptées au cadre séquentiel pour bénéficier de garanties déterministes ; réciproquement, des techniques de suites individuelles permettent de calibrer automatiquement des méthodes statistiques pour obtenir des bornes adaptatives en la variance du bruit. On étudie de tels liens sur plusieurs problèmes voisins : la régression linéaire séquentielle parcimonieuse en grande dimension (avec application au cadre stochastique), la régression linéaire séquentielle sur des boules L1, et l'agrégation de modèles non linéaires dans un cadre de sélection de modèles (régression avec design fixe). Enfin, des techniques stochastiques sont utilisées et développées pour déterminer les vitesses minimax de divers critères de performance séquentielle (regrets interne et swap notamment) en environnement déterministe ou stochastique.

碩士
國立臺灣大學
人類學研究所
101
‧ Abstract This study examines the cross border marriages migration of Africans to Taiwan. It is based on one year and six month fieldwork among Afro-Taiwanese couples currently living in Taiwan. Most of the African interviewees are from West Africa, Central and South Africa. They came to Taiwan under different types of visas such as student visa, tourist visa, working visa and family visit visa. ‧ The empirical findings of my research showed that the Afro-Taiwanese cross-border marriage has been increasing most consistently and becoming a global trend rather than something exotic. On the one hand, it has its source in the effect of Taiwanese men’s migration to Africa for work and African migration to Taiwan for tourism, work, and studies on the other hand. It is mostly African men who marry Taiwanese women, but African women marrying Taiwanese men are less common. ‧ The primary reason the Taiwanese women chose to marry African men rather than Taiwanese men, American or Japanese men is their desire to find a lifelong partner. Similarly, the reason Taiwanese men married African women rather than local women are because they are fed up with local women’s materialistic tendencies. However, most of my informants stated that they marry their spouses because they love them. The specificity of the Afro-Taiwanese marriage is that none of my informants met his/her respective partner through the marriage agencies. ‧ My informants are well educated and belong mostly to middle class families. Parents from both sides opposed their children cross-border marriages because they believe that their children have married down. Moreover, sharing a common religion combined with their sexual life has played a significant role in their domestic power relationships and in dealing with cultural differentials. Finally, the African grooms are mostly involved in private businesses. ‧ This research aims to investigate the Afro-Taiwanese couples in cross-border marriages as there has never been in the past any study in my understanding made to specifically focus on the phenomenon. The thesis will generate new insights not ever been recorded in the literature, enlightening the differences between the Afro-Taiwanese cross-border marriages with the Southeast Asian cross-border marriages in Taiwan.

Disturbances are integral to the structure and functioning of the boreal forest. However their effects upon the underground components in this ecosystem are still largely unknown. In this thesis, I describe the ectomycorrhizal and understory plant communities in the black spruce boreal forest of the Abitibi region, Québec, and discuss the effects that both forest fires and logging have on the ectomycorrhizal community, nutrient supply rates and decomposition rates. The ectomycorrhizal community from black spruce, characterized by morphotyping and molecular techniques was dominated by Cenococcum geophilum and three Piloderma species. The plant community was made up of a mosaic of vegetation patches, which are described in this thesis, as either Sphagnum dominated plots, which associated with Sphagnum, Gaultheria hispidula and Picea mariana; or ericoid/lichen dominated plots, which associated with Lichen and Vaccinium angustifolium. Statistical analysis revealed that the effect of the disturbances was largely insignificant to the ectomycorrhizal community, nutrient supply and decomposition rates, and most differences were between transects. However, both the understory plant community plot types and abundance of individual plant species were found to have significant correlations with the most abundant ectomycorrhizal species. This suggests that if we want to know how the ectomycorrhizal community will be affected by disturbances, we should look at changes in the plant community due to disturbances.

Understanding how populations are structured and how they use natural and anthropogenic spaces is essential for effective wildlife management. A total of 510 barren-ground (Rangifer tarandus groenlandicus), 176 boreal (R. t. caribou), 11 mountain woodland (R. t. caribou), and 39 island (R. t. groenlandicus x pearyi) caribou were tracked with satellite collars in 1993-2009 in the Northwest Territories, Nunavut, and northern Alberta. Using satellite location data and hierarchical and fuzzy cluster analyses, I verified that Cape Bathurst, Bluenose-West, Bluenose-East, Bathurst, Beverly, Qamanirjuaq, and Lorillard barren-ground subpopulations were robust; the Queen Maude Gulf and Wager Bay barren-ground subpopulations were distinct. Dolphin and Union island caribou formed one population; boreal caribou formed two distinct subpopulations. Females in robust subpopulations were structured by strong annual spatial affiliation; those in distinct subpopulations were spatially independent and structured by migratory connectivity, movement barriers, and/or habitat discontinuity. An east-west cline in annual-range sizes and path lengths supported the subpopulation structure identified for migratory barren-ground caribou. I analyzed satellite location data to determine parturition dates and activity periods for all caribou ecotypes. For parturition dates I found a north-south cline for boreal caribou, west-east cline for migratory barren-ground caribou, and ecotype and subspecies clines for boreal and barren-ground caribou. Based on annual changes in movement rates I identified eight activity periods for boreal and tundra-wintering, 10 for mountain woodland, and 12 for migratory barren-ground caribou. Based distribution and movements, boreal caribou avoided seismic lines during periods when females and calves were most vulnerable to predators or hunters. They crossed fewer seismic lines and travelled faster when they crossed them than expected. Caribou avoided areas ≤400 m from seismic lines where they could space away from them suggesting that they perceive these as risky areas. I defined secure habitats as areas that were >400 m from anthropogenic linear features. Population growth rates were higher in areas where they had access to secure unburned habitat and where most of that was in patches >500 km2. Critical habitat for boreal caribou is a habitat state that provides “security” from predation risk and facilitates the effectiveness of their anti-predator strategies.
Ecology