Industrial residuals in land reclamation: enhancing soil recovery and ecological function in disturbed glacial soils

Abstract

This dissertation investigates the reclamation potential of industrial residuals in remediating disturbed glacial soils in Northeastern Ontario. Focusing on two distinct yet similarly degraded landscapes — abandoned aggregate borrow pits and acid- and metal-affected mixed-wood forest soils in the Sudbury region — the research explores the application of industrial by-products to enhance soil fertility, facilitate revegetation, and support ecological restoration. The study is structured around three research objectives: first, assessing passive recolonization processes and dominant functional traits in abandoned borrow pits; second, evaluating the efficacy of industrial residues, including pulp and paper mill sludge, biomass boiler fly ash, and municipal biosolids, in improving borrow pit soil fertility and facilitating vegetation establishment; and third, testing the potential of these residues to ameliorate acidic and metal-laden soils for reforestation efforts in post-mining landscapes. The research incorporates a thorough analysis of soil and vegetation dynamics, functional trait diversity, and soil-organism interactions across experimental and natural sites. By determining community-weighted mean (CWM) and Rao’s Quadratic Entropy Index analyses, the study quantifies the functional role of plant traits in supporting ecosystem resilience and stability of abandoned borrow pits. Results demonstrate the significant but variable effects of land applying industrial solids on soil quality, with implications for both nutrient dynamics and biological activity. Notably, the application of these residues to acidic soils supports positive vegetation outcomes, particularly for pioneer and stress-tolerant species adapted to low-nutrient environments. Additionally, findings highlight the challenges associated with northern soil reclamation, including frost heave and the limited microbial and nutrient availability in exposed, compacted substrates. The research contributes to the understanding of reclamation strategies in regenerating forest ecosystems, emphasizing the importance of tailored, site-specific amendments to improve soil health and promote sustainable land recovery. The outcomes of this thesis have broad implications for land management policies in resource-extractive landscapes, underscoring the need for long-term monitoring, adaptive management, and integrated use of local industrial by-products to restore ecosystem functionality in severely degraded soils.