Exploration and extraction activities in the Alberta Oil Sands region have degraded thousands of hectares of land, about 40 % of which were once covered by peatlands. To date, there is very little information regarding the reclamation of peatlands, and even less related to their reclamation after oil sands disturbances. The results of this study will be used to develop protocols for the reclamation of peatlands after disturbance due to oil sands exploration and extraction operations in the Alberta Oil Sands region. Carex aquatilis is considered to be an ideal candidate species for initiating reclamation because it is a common pioneer species of disturbed landscapes, and has been shown to have a wide range of tolerances for several environmental factors in other areas of its overall distribution. The results of this study showed even wider ranges of tolerance than previous studies have reported, and did so using an ecological field study, a greenhouse propagation study, and a greenhouse Na+ tolerance study. A field study used vegetation surveys and environmental data to determine that Carex aquatilis is abundant in several wetland types and is not strongly associated with any of the species with which it was commonly found. In addition, C. aquatilis also was present across wide ranges of environmental variables including pH, conductivity, shade, water depth, Na+ concentration of surface water and percent organic carbon content of the substrate. These wide ranges of tolerance should allow C. aquatilis to establish after many types of disturbance. A greenhouse propagation study tested for population differences in percent germination after four stratification treatments, three stratification durations and four germination treatments. The overall best stratification treatment was to store seeds moist at 4°C for 30 days. The most effective germination treatment across all treatments was to plant seeds just below the surface of the substrate with the water level maintained at 1cm below the substrate surface. Only 9% of all sown seeds germinated. There were differences in germination rates between populations, although it is unknown whether these differences were due to differences in viability, timing of seed maturation, stratification requirements or germination requirements. A greenhouse Na+ tolerance experiment tested for differences in Na+ tolerance between four populations and two age classes to assess the efficacy of C. aquatilis as a pioneer species after oil sands surface mining disturbance. Five Na+ concentrations ranging from 5 to 2000 mg L-1 were tested. Plants showed no differences in Na+ tolerance between populations, but younger plants were more susceptible to damage from Na+ stress than older plants so it is recommended that older plants are used to initiate reclamation. It is also recommended that Na+ be managed on surface mine reclamations so that it is below 500 mg L-1.

<p> Plants can control water loss through their stomata in response to changing environmental conditions. Some research has been done on predicting stomatal resistance from climate variables such as solar radiation intensity, temperature, and vapour pressure deficit, but the factors involved are numerous and complex. Information on evapotranspiration from non-cultivated vegetation under field conditions is relatively scarce. This study was carried out in a subarctic coastal wetland on James Bay, an area for which little data exists. Leaf resistance measurements were collected in the field with a diffusion porometer as the 1988 growing season reached its peak. Meteorological data were also recorded. The main species examined was Carex aquatilis, a common sedge with a circumpolar distribution. As has been previously found, field resistances were lower than those reported for greenhouse-grown specimens. Attempts to derive a multivariate regression model to predict leaf resistances had a maximum explained variance under 40%. However, Principal Components Analysis suggested that cool, sunny, low-VPD conditions tend to accompany low leaf resistances. An increase in leaf resistance occurs when solar radiation intensities are low, or when the air is warm and dry. In addition, Carex aquatilis from drier areas showed less growth, and generally higher leaf resistances, than plants growing in saturated soils. Since climate models predict higher temperatures and lower soil moisture for the study area, due to carbon dioxide-induced warming, higher stomatal resistances could result. If these changes are severe enough, primary production could be reduced in the subarctic wetlands. Through the food chain, this could possibly affect species important to the economy and ecology of northern areas.</p> / Thesis / Candidate in Philosophy