| Summary: | This thesis explores indicator tools to measure the ecological impacts of changes to the food system. The concept of a ‘foodshed’ provides a framework to explore the relationships between ecological impacts and where food system activities occur. Indicators of resource use and reuse are developed to describe the shape and size of the foodshed.
Paper 1 presents a review of six indicator-based tools from the literature. Using a three criteria definition of ecological sustainability in the food system - increased resource efficiency, decreased pollutant loading, and increased output reuse - Paper 1 examines the suitability of these tools for evaluating the impacts of municipal food policy driven-changes in the location of activities, processes within activities and diet composition.
Paper 2 describes the shape of a foodshed, and investigates how changes in Toronto’s waste management impacted the reuse of food-related nitrogen. Reuse increased from 1% in 1990 to at least 4.7% in 2001, through backyard composting and the land application of processed sewage. By 2004, in spite of household organics collection, reuse decreased to 2.3%, due to a reduction in land-applied sewage. The analysis suggests that sewage management has a larger impact on the reuse of food nitrogen than household solid waste management.
Paper 3 quantifies the size of the foodsheds of Canada and the Greater Toronto Area (GTA), and evaluates the feasibility of self-sufficiency and its impact on the total land area used for production. Nationally, there is sufficient harvested land area to meet 95% of the land area needed for self-sufficiency. Self-sufficiency is only feasible for the GTA by drawing from a foodshed extending 400 kilometres beyond its boundary. Given current yields, total self-sufficiency would occupy more land area than currently used domestically and abroad. Higher yields or a change in diet could decrease the size of the foodshed.
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