No description available.

No description available.

Boreal regions account for a significant portion of Canada's landmass and economic resources (e.g., forestry, mining, and oil and gas). The inadvertent release of pollutants from industrial activities within these regions stress the need for realistic ecological risk assessments, which can be attained through the use of standardized soil toxicity test methods. Despite the geophysical and economic significance of boreal regions, standardized soil toxicity test methods applicable to these regions are lacking. To help alleviate this gap in ecotoxicology, the objectives of this thesis included the development and application of a new suite of boreal species for the assessment of contaminants in boreal soils. Specifically, research was directed towards the development of a new oribatid mite test, using Oppia nitens (C.L. Koch). Oribatid mites represent the most abundant and diverse microarthropod species in forest soils, significantly contributing to nutrient cycling and soil formation processes; however, these organisms are consistently under-represented in soil ecotoxicological assessments. The applicability and limitations of the use of O. nitens were demonstrated such that lethal and sublethal endpoints could be derived from the assessment of soils. The performance of O. nitens across numerous soils varied such that adult survival was unaffected by soil characteristics, however, reproduction was limited by soil organic matter content. An evaluation of the sensitivity of O. nitens, using a model polycyclic aromatic hydrocarbon was also conducted in a standard test soil. Phenanthrene is a common contaminant in soils, and accumulates within organic-rich horizons, within which oribatid mites live. Therefore, the study was designed to examine the toxicity and bioaccumulation potential of phenanthrene to O. nitens, with a comparison of effect to other soil invertebrate species, as presented in the literature. Oppia nitens was susceptible to phenanthrene at levels comparable to other soil invertebrate species, and the bioaccumulation of the phenanthrene increased with increasing exposure concentration, although steady-state was not achieved during the four-week exposure duration. The accumulation was biphasic in nature, likely a result of initial cuticular sorption processes, followed by the contribution of other processes (e.g., dietary uptake). The elimination of the phenanthrene was not complete, in that at the end of the elimination phase, tissue residues were similar to that observed in the initial gradual accumulation (e.g., by cuticular processes). However, the resultant bioaccumulation factors (BAFs) were relatively low, indicative of limited trophic transfer and biomagnification for this species. Following the development of an O. nitens assay, a further study was conducted to compare the sensitivity of O. nitens to other boreal soil invertebrate species, as well as to standard test species. Soil toxicity tests were designed, using field-collected reference and contaminated (petroleum hydrocarbon- and salt-impacted) soils, using an expanded suite of boreal species (plants: Pinus banksiana, Picea glauca, Picea mariana, Populus tremuloides, Calamagrostis canadensis and Solidago canadensis; earthworms: Dendrodrilus rubidus; and springtails: Folsomia nivalis and Proisotoma minuta). The sensitivity of the boreal species was then compared to that of currently published standard soil toxicity test species (agronomic plants: Elymus lanceolatus and Trifolium pratense; earthworms: Eisenia andrei; and springtails: Folsomia candida). Estimated species sensitivity distributions (ESSDs) were generated to determine whether the boreal and standard test battery of species exhibited differences in their overall sensitivity to the contaminated soil. With regards to the petroleum-hydrocarbon impacted soil, the suite of boreal species was more sensitive relative to the suite of standard test species; however, upon exposure to the salt-impacted soils, no differences in sensitivity were evident between the boreal and standard suite of test species. In both soils, the performance of O. nitens was similar to that observed by the collembolan species. The evaluation of boreal species and soils also took into consideration the use of distinct soil horizons. The layering of horizons was feasible from the initial collection to reassembly for testing in the laboratory, and plant growth was unaffected by this design. However, soil invertebrates demonstrated a preference or avoidance tendency for one horizon over another, and as a result, the assessment of individual horizons was recommended for all future testing. The compilation of research presented herein provides the basis for the standardization of ecologically-relevant test species and methods for the assessment of contaminated soils in boreal regions.

The Owl-Flintstone range in southeastern Manitoba is among the most at risk in the province. Through a series of transects and plots established throughout the study area, this study characterized calving habitat at a fine scale, examined the use of caribou calving areas by large mammals and examined if a calving habitat model correctly identified high quality calving habitat. Parturient females utilized black spruce dominated islands and peninsulas on lakes as well as islands and peninsulas in bogs. Bear utilized both predicted low and high quality sites. Black spruce and lichen cover were significantly greater within known calving sites compared to predicted low quality habitat. Forbs, herbs and downed woody debris values were significantly lower within known calving sites compared to predicted high quality sites. The calving habitat model correctly identified both high quality and low quality calving habitat in the Owl-Flintstone range, however parameters could be refined.

The feasibility of wood based energy plants in the off-grid Brochet community in Manitoba were analyzed by survey, interviews and document review in this research. Four areas were explored to assess the suitability of biomass energy generation, namely: the community’s perspective, resource assessment, technology availability, and cost attractiveness. Harvesting sufficient woody biomass from local wild fire burnt areas, in particular, as well as local green forests could be an appropriate and feasible option. A heat only plant is considered to be the best choice for biomass plant establishment in Brochet, followed by combined heat and power plants. A cost analysis showed that a biomass plant at Brochet is more economical than the current planned investment in the diesel power facility. The lack of resolve about who wants to run and pay for the operation and the uncertainty of the reliability of biomass technologies are two large barriers to biomass energy generation in the community. Overall, biomass energy generation options are promising to eliminate or reduce the use of fossil fuel in Brochet.

Variation in snow albedo feedback (SAF) among CMIP5 climate models has been shown to explain much of the variation in projected 21st Century warming over Northern Hemisphere land. Prior studies using observations and models have demonstrated both considerable spread in the albedo, and a weak bias in the simulated strength of SAF, over snow-covered boreal forests. Boreal evergreen needleleaf forests are capable of intercepting snowfall throughout the snow season, which has a significant impact on seasonal albedo. Two satellite data products and tower-based observations of albedo are compared with simulations from multiple configurations of the Community Climate System Model (CCSM4) to investigate the causes of weak simulated SAF over the boreal forest. The largest bias occurs in April-May when simulated SAF is one-half the strength of SAF in observations. This is traced to two canopy snow parameterizations in the land model. First, there is no mechanism for the dynamic removal of snow from the canopy when temperatures are below freezing, which results in albedo values in midwinter that are biased high. Second, when temperatures do rise above freezing, all snow on the canopy is melted instantaneously, which results in an unrealistically early transition from a snow-covered to a snow-free canopy. These processes combine to produce large differences between simulated and observed monthly albedo, and are the sources of the weak bias in SAF. This analysis highlights the importance of canopy snow parameterizations for simulating the hemispheric scale climate response to surface albedo perturbations. A number of new experiments are described as recommendations for future work.

Dinitrous oxide (N2O) is a potent greenhouse gas some 354 times stronger than carbon dioxide (CO2) in the atmosphere. Recent studies show that lake denitrification contributes to a considerable part of the global N2O emissions. Despite this, lake-N2O emissions are not being accounted for in global greenhouse gas modeling because it has not yet been accurately understood and quantified. The aim of this study was to assess how denitrification varies between and within boreal lakes and how it is controlled by nitrate- (NO3) and carbon (C) availability and temperature. Studies on denitrification were performed using the acetylene inhibition technique on sediments from three lakes in northern Sweden (February to August, 2014). Results showed that denitrification was correlated (linear regression, r2=0.71) with NO3 concentrations in the hypolimnion water at ambient conditions and that additions of NO3 up to a concentration of 50 µg NO3-N L-1 increased denitrification. Temperature increased denitrification in all lakes, at all sites except in one lake in July, when nutrient concentrations were at its lowest. The spatial and temporal variation in denitrification was small at ambient conditions (1-3 µmol N2O m-2 h-1)but the variation in the response to nutrient additions and temperature increase was very high. This was in part attributed to differences in dissolved organic C (DOC). These findings have important implications for future denitrification research and how lake-N2O production is included in greenhouse gas modeling and contributes to our knowledge on how northern boreal lakes may respond to enhanced nutrient loadings and global warming.

This study investigates surface water and groundwater interactions in a wetland/peatland region surrounding Fort McMurray, Alberta. This work measured local meteorology, water table variation, and isotope and geochemistry concentrations over a two year period. Results from vertical water budget calculations showed episodic runoff events ranging between 0 and 38 mm/yr. Groundwater evaluations showed limited groundwater gradients with mean hydraulic conductivities of 1.01*10-5 cms-1 (NE7) and 1.78 * 10-5 cms-1 (SM8). Overall, groundwater flux estimates were variable and heterogeneous across the catchments areas. Isotopic composition showed mixing between winter precipitation, groundwater and surface water, with groundwater representing the average input signature. This study showed that runoff events were largely associated with spring freshet and significant summer storm events. / Graduate

The last century, forest fires have decreased in frequency due to efficient fire-suppression along with the growth of the industrial forestry. Since 1990, fire has been reintroduced under controlled forms to recreate burnt habitats. Many species that are dependent on, or benefits from, forest fires have increased since fire was reintroduced. The importance of connectivity is often addressed in ecological research. This is particularly important for species dependent on short-lived habitats such as burnt forests. The aim of this study was to investigate if a higher connectivity between burnt forests leads to an increased occurrence of fire-related insects. The study also attempts to determine in what way connectivity and other variables in a burnt forest, such as amount of living and dead wood, distance to the coast and altitude, affects fire-related species. To investigate this, six burnt forests in Västerbotten County were sampled for fire-related insects. The sites were chosen along a gradient from high to low connectivity and close to far from the coast. The results showed that there are too few burnt forests in Västerbotten County to conduct a study of this magnitude. Still, the results provide an insight in how different environmental variables affect the number of fire-related species. The results showed a trend that increasing amount of living and dead wood and longer distance from the coast increase the local richness of fire-related species. Concerning the main aim in the study about connectivity, the analysis gives no support to either accept or reject the hypothesis.

Although boreal forest management typically results in an increased frequency of even-aged forest stands in managed landscapes, fire history research suggests that much of the natural forest mosaic is composed of stands characterised by multiple cohorts of trees. To aid in the development of multicohort management, I investigated stand structural characteristics and small mammal communities as a function of their tree cohort structures. I also tested key alternatives: stand age, productivity, and tree species composition, as correlates of structural variation and small mammal communities. Results reveal that in mixedwood and black spruce forests, three-dimensional structure of boreal forests is strongly correlated with small mammal community structure, and indicate that tree diameter distribution is a succinct descriptor of such structural variation, performing better than alternative stand characteristics. This represents a new approach to characterising habitat supply as a function of within-stand heterogeneity, contrasting with existing approaches that focus on among-stand characteristics.