Ce Mémoire de maîtrise tentera de combler un vide historiographique dans l'histoire de l'Abitibi-Témiscamingue, et plus particulièrement dans l'histoire de la ville de Senneterre, entre les annés 1950 et 1988. Cette période correspond aux années d'opération de la station-radar RCAF Senneterre et marque l'apogée de cette petite ville à bien des niveaux : économique, démographique, socioculturel et sportif. Il s'agit également d'une époque (plus particulièrement les années 50 et 60) où la dynamique ethnique de Senneterre est complètement bouleversée : plus de trois cent militaires, majoritairement anglophones et protestants viennent s'établir au Mont-Bell, à quatre kilomètres du bastion francophone et catholique qu'est Senneterre. Et non seulement ils y habitent pendant plus de trente ans, mais ils participent activement au nouveau dynamisme et à l'effervescence qui s'emparent de Seneterre. Nous examinerons donc le fonctionnement paramilitaire de la station-radar, mais également les impacts de sa présence et les interactions qu'elle engendre avec sa communauté hôtesse, la ville de Senneterre. Bref, ce Mémoire n'aborde pas simplement un sujet se limitant à l'histoire locale, mais offre plutôt un regard sur les effets d'un conflit global sur une petite municipalité du nord-ouest québécois dans un contexte d'après-guerre et de grands changements sociaux dans la province.

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

The presence of mosses in black spruce forests is known to have an important impact on the availability and abundance of nutrients in this ecosystem. Mosses contribute to long-term accumulation of organic matter and storage of nutrients as well as to short-term nutrient release. In the boreal forest of northwestern Quebec, the effect of mosses on nutrient cycling was examined within the framework of a chronosequence ranging from 25 to 300 years of age. Laboratory and buried bag incubations, total nutrient digests, respirometric and root abundance measurements as well as moisture and temperature measurements were done to characterize the nutritional status of the organic matter profiles. In general, no change in moss accumulation, or nutrient storage or availability across the chronosequence could be detected. There were, however, differences between feather mosses and Sphagnum mosses, the latter having significantly lower levels of nutrients than the former in terms of mineralizable nitrogen and total carbon, nitrogen, phosphorus, magnesium and potassium content. The nutritional profile of moss cores showed different horizons, reflecting differences in organic matter quality down the organic layer. More specifically, nitrogen availability on a concentration basis as well as root abundance decreased with depth. Forest floor temperature seemed to confine the most biologically active horizon, referred to as the active layer, to a shallow depth, however neither temperature nor moisture seemed to explain the nutritional differences between feather mosses and Sphagnum mosses. These results may lead to practical consequences in that they show a clear distinction between the effects of feather mosses and Sphagnum mosses in nutrient cycling, suggesting that moss cover, might be useful as an indicator of site nutritional status. The results also show that accumulation of nutrients in organic surface horizons, as has been observed elsewhere, does not appear to occur in blac

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The general objectives of this thesis project were to describe and to understand the dynamics creating occurrence patterns of saproxylic wood-feeding Coleoptera in snags (i.e., standing dead trees) of black spruce and aspen along the decay gradient. The first part of this thesis focuses on pre-landing host-selection behaviours in coniferophagous species, i.e. the use of host-produced volatiles to locate potential hosts. Results presented suggest that most saproxylic wood-feeding beetles studied herein use volatiles to orient towards potential habitat patches but that olfactive information does not allow the identification of suitable hosts at close range prior to landing. The second part of the thesis focuses on the occurrence patterns themselves and on underlying mechanisms. Sampling was conducted using snag dissection, a novel method allowing a better characterization of larval stage wood-feeding assemblages. Opposite patterns were observed between the two host species studied, as abundance and species richness were highest in early stages of decay in spruce, and in middle to late stages of decay in aspen. In aspen, numerous nutritional and physical parameters of dead wood correlated significantly with wood-borer occurrence. However, most of these parameters were strongly auto-correlated, and the explanatory model most highly ranked by model selection consisted of only a snag age term. Also, a simple neutral model based on temporal autocorrelation in occurrence probability produced patterns similar to those observed through sampling. In the last original paper presented, results suggest that wood-boring larvae select for specific types of substrate in highly variable aspen snags. This selection on the part of the larvae likely decreases the impact of the oviposition site on subsequent larval performance, and could explain the lack of strong selection seen on the part of the mother. My results suggest very different host-selection dynamics in black spruce and aspen, as assemblages of the former were dominated by early-decay species with volatiles-driven colonization dynamics, while middle- to late-decay species dominated the later, seemingly through mostly neutral colonization mechanisms. Some of my findings suggest that patterns observed in black spruce and aspen could be extrapolated to a coniferous/deciduous host dichotomy in colonization dynamics of woodfeeding species, based on divergent secondary chemistry and wood structure.

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Trembling aspen (Populus tremuloides Michx.) were observed growing along roads far north from the area where it dominates, in sites dominated by black spruce (Picea mariana (Mill.) B.S.P.) forests. This study examined the distribution of aspen at an early development stage and the conditions in which they are growing in a black spruce/feathermoss forest type in northwestern Abitibi, Quebec six years following harvesting. In this region, aspen are appearing in logged and burned areas that had been previously dominated by black spruce. The relationship of aspen growth with Ca availability and mineral soil access is the main focus of the study. Soil and foliar samples from aspen seedlings were collected from roadside, slash and cutover locations during the summer of 2003. Trees were also measured for height and basal diameter. Microsites where aspen was growing and where it was absent were compared to determine whether aspen was associated with specific microsites soil properties. The results suggest that there are differences in the growing conditions for aspen between different locations but that the trees are growing successfully in all of the three location types. In the cutovers, aspen seedlings were consistently found in association with patches of Polytrichum moss. All the sets of data indicate that Ca availability and access to mineral soil are not the main factors influencing the distribution of aspen but that soil pH, or a factor relating to pH, may be important.

Mole drainage is an inexpensive form of drainage particularly suited to clay soils. / Mole drainage is approved by Le Conseil des Productions Vegetales du Quebec to drain clay soils with low hydraulic conductivity. A few known trials on this technique of drainage have been done in Ontario and Alberta. In England and New Zealand, this technique is widely used. The large surface of heavy clay soil cultivated in Abitibi-Temiscamingue makes this region an excellent choice for trying this technique. / Two sites established on two soil series (Palmarolle, Roquemaure) have been moled in Abitibi-Temiscamingue. These soils represent 21% of the cultivated land in this region. Twelve plots have been moled at varied depths, spaces and lengths. Physical and chemical soil properties have been measured to identify their influence on mole drainage stability. Water table, rainfall and the stability of the mole drains were monitored for three summers. Mole drain stability was observed with a borescope. Maturity growth and yield of a hay crop, and three types of cereals were measured. / The mole drainage technique is satisfactory in heavy clay. The organic matter (${>2 %}$), the water content of the soil (${>40 %}$) at moling time and a small amount of rainfall (${<6}$ mm) in the first week after moling positively influenced the stability of the mole drains. Some mole drains have kept 75% of their initial opening after three years of life. The water table was lower on one mole drained site. The yield of the hay and the three cereals were higher on the moled parcels. (Abstract shortened by UMI.)