Hutchinson, Tom C.

Natural establishment of vegetation on mine tailings is generally limited. Understanding the processes leading to vegetation germination and the survival mechanisms that vegetation species employ in these harsh environments is critical to future remediation efforts. As metalliferous mine tailings are generally nutrient-poor, high in harmful metals, and acidic, vegetation species require distinct mechanisms to germinate and survive in such harsh environments. In this study, edaphic and biotic factors linked to vegetation establishment and diversity were studied at two nickel-copper (Ni-Cu) tailings sites near Sudbury, Ontario. One site had experienced minimal treatment, and the second site was split into partial (hand-distribution of lime) and full (lime, fertilizer, seeding) treatment areas. Tailings were generally acidic, low in organic matter and "available" nutrients, and high in metals such as Al, Cu, Fe, and Ni, but these physical and chemical properties were extremely spatially variable. At both sites, vegetation was distributed in sparse patches, with the greatest diversity in treated areas. There was no clear link between metals and vegetation establishment/diversity at the sites. The primary limiting nutrients on the tailings were phosphorous (P) and potassium (K), and while there were areas of increased soil fertility at the sites, they were not clearly associated with increased vegetation diversity. Both traditional ecological succession and nucleation succession patterns were observed on the site, and the chief species associated with nucleation were primary colonizing trees such as B. papyrifera and P. tremuloides. The relationship between B. papyrifera nutrient retranslocation and tailings restoration was assessed and while B. papyrifera at the sites were deficient in P and K, the trees efficiently retranslocated both P and K during senescence. This research can provide insight into possibilities for future revegetation of similar tailings, enabling industry to make educated decisions when choosing where and how to revegetate, mimicking natural succession patterns.

Author Keywords: Acid-mine drainage, Betula papyrifera, ecosystem health, metals, Sudbury, tailings

This thesis re-imagines the social sustainability of civic agriculture. This entails critically examining the idea of sustainability and exposing why a tendency to undertheorize its social dimension is problematic for how we think about sustainability, and consequently for how we do sustainability. What is demonstrated is that we can overcome this tendency by adopting Stephen McKenzie's understanding of social sustainability as a positive condition and/or process within a community. Once brought into contact with the concept of civic agriculture as presented by Thomas A. Lyson, and expanded upon by others, this broadened understanding of social sustainability reveals that we can think of civic agriculture as both a means to, and an expression of, social sustainability. Specifically, this thesis argues that it is civic agriculture's community problem-solving dimension which animates civic agriculture in such a way that it creates the sort of condition and/or enables the sort of process which reflect aspects associated with a substantive and/or procedural understanding of social sustainability. This re-imagining of the social sustainability of civic agriculture provides ways to defend civic agriculture from its critics and is exemplified by drawing from a personal encounter with civic agriculture. In the end, it is proposed that in light of this research there are now good reasons to re-examine civic agriculture and to critically re-imagine what qualifies who as a civic agriculturalist so that the contextual nature of the social sustainability of civic agriculture can be better respected.

Author Keywords: civic agriculture, community problem solving, local food systems, social sustainability, Stephen McKenzie, Thomas A. Lyson