Environmental effects assessment of oil and gas development on a grassland ecosystem

Abstract

The northern Great Plains of Saskatchewan is one of the most significantly modified landscapes in Canada. While the majority of anthropogenic disturbance to Saskatchewan’s grasslands is the result of agricultural practices, oil and gas activity are of increasing concern to grassland conservation efforts. Although such developments require formal regulatory approval (Environmental Impact Assessment), follow-up and monitoring of the effects of oil and gas development on grasslands is not common practice. In the absence of empirical based follow-up and monitoring, the actual environmental effects of petroleum and natural gas (PNG) development on grassland ecology and the spatial extent of development are largely unknown.

This thesis examines the spatial and temporal extent of PNG development and its effects on grassland ecology within a PFRA (Prairie Farm Rehabilitation Administration) pasture in southwest Saskatchewan. The extent of the changes to infrastructure and the actual impacts from development within the study area were documented from 1955 to 2006. The actual impacts of oil and gas activity on grassland ecology were determined by analyzing ground cover characteristics, soil properties, and community composition at lease sites and compared to reference pasture sites. Associated with construction practices, lease sites had low herbaceous, Lycopodiaceae, litter, organic horizon (Ah) thickness, and soil compaction values. Lease sites were also found to have low desirable species diversity, range health values, and greater undesirable species presence. Impacts from development were amplified at active, highly productive lease sites. The impacts associated with PNG development were also found to persist for more than 50 years, and extend 20m – 25m beyond the physical footprint of infrastructure. This research will contribute to monitoring and mitigation measures for oil and gas development within Saskatchewan and Canadian grasslands.