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The affordability crisis in the North American housing market has prompted the construction industry to reexamine technologies designed to lower cost through the factory mass production process. This thesis concentrates on modular prefabricated housing in the Province of Quebec in order to determine if this housing option can supply a less expensive alternative to comparable conventionally built housing. As issues of construction cost are allied with the quality of construction, a comparison between the conventional and the manufactured building industries, at this level, is also essential. Surveys evaluating sales cost and quality of construction have been developed for the modular prefabricated and conventional single family detached housing industry for the Province of Quebec. Fifteen prefabricated home builders and six conventional home builders were surveyed in order to facilitate the comparison between the two industries. It was found, based on the builders surveyed, that the average level of construction quality was consistent in both industries. The prefabricated residential home builders, however, proved on average to be approximately ten percent more expensive than the conventional home builders surveyed. Reasons for these cost discrepancies have been found to be related to the high start-up costs inherent in the manufactured housing industry, the overall cyclical market demand for housing, as well as price protection for distributors of manufactured housing.

I investigated oribatid mite assemblages in a beech-maple forest in southwestern Quebec. I first examined the effects of four forest stand types (American Beech (Fagus grandifolia) dominated, Sugar Maple (Acer saccharum) dominated, mixed deciduous and coniferous plantations) and three open site types (agricultural field, fallow pasture and unmanaged hay field) in structuring oribatid mite assemblages. My second study focused on the effects of changes in litter depth (a factor that varies by stand type) on the structure of oribatid assemblages. / Stand type was shown to be an important factor in determining oribatid mite abundances, species richness and assemblage composition. Results from the second study confirm this, but revealed no effect of changes in litter depth on oribatid mite assemblages. These findings serve to demonstrate that while examining specific environmental factors as determinants of oribatid mite diversity and distribution is important, more general factors such as habitat type cannot be ignored.

Mechanical weed control, chisel plow tillage and organic fertilization are important components of sustainable agriculture that can contribute to the preservation and improvement of soil and water resources. These practices can each affect weed communities, crop weed interactions and crop yields. Little is known about their combined effects on weed populations and weed community dynamics in common cropping systems. The main objective of this project was to determine the effects of crop rotation, weed control, tillage and nutrient source and their interactions on weed communities and weed emergence. The field experiment was conducted on a Sainte-Rosalie clay and a Duravin loam in Saint-Hyacinthe, Quebec, Canada, in 1996 and 1997. Mechanical control was not as effective as chemical control in controlling weed populations. Weed density increased after the second pass of the rotary hoe in soybean. Cultivation in corn triggered flushes of weed emergence, but corn yield was not affected by the increase in weed density. Chisel plow tillage reduced the efficacy of mechanical weed control in both crops. Reduced soybean yields were partly attributed to the large quantities of corn residues under chisel plow tillage. Nutrient source had no effect on weed densities. However, environmental stress conditions experienced in spring 1997 resulted in reduced crop growth and increased weed biomass under organic fertilization. Seed production of dominant residual weed species was greater under mechanical compared with chemical weed control, but was unaffected by tillage and nutrient source. Particular attention to weed management will be required when including both chisel plow tillage and organic nutrient source in a corn-soybean rotation, especially when resorting to mechanical weed control only.

A climate controlled, dynamic chamber was used to measure carbon dioxide (CO$ sb2$) and methane (CH$ sb4$) exchange on an ombrotrophic peatland. The study periods were July to early November 1995, and early May to July 1996. Five sample sites, showing ecological and hydrological contrast, were investigated. Measurements of Net Ecosystem Exchange showed peak photosynthetic capacity (GP$ sb{ max})$ ranging from 0.52 $ pm$ 0.04 mg C m$ sp{-2}$ s$ sp{-1}$ (June 1996) to 0.03 $ pm$ 0.02 mg C m$ sp{-2}$ s$ sp{-1}$ (early November 1995). Dark respiration measurements ranged from $-$0.21 $ pm$.02 mg C m$ sp{-2}$ s$ sp{-1}$ (June 1996) to $-$0.02 $ pm$.01 mg C m$ sp{-2}$ s$ sp{-1}$ (late May 1996), and showed significant relationships to soil temperature at all sites. Site average methane measurements ranged from 29-72 mg m$ sp{-2}$ d$ sp{-1}$, and showed a strong relationship to water table on a seasonal basis, but a poor correlation to simultaneous NEE. Modelled Net Ecosystem Productivity (NEP) among sites ranged from 17.1 to 115 gC over the entire study period. The CO$ sb2$ exchanges in late spring and early fall made a large contribution to the figure due to the imbalance in the photosynthetic and dark respiration components of the carbon budget. No discernible relationship was found between seasonal NEP and methane release. The results suggest a large importance of the extreme ends of the growing season in an analysis of the carbon budget of peatlands, periods hitherto little investigated. They also suggest that NEP/methane connections may be restricted in their significance to mainly flooded mires.

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