Characterising biocomplexity and soil microbial dynamics along a smelter-damaged landscape gradient.

Soil micro-organisms are an integral but often underestimated part of plant and soil ecosystems. Long-term industrial air pollution in the Sudbury, Ontario region has altered vegetation and soil, and therefore, possibly, soil microbial function. This study focuses on the historical pollution gradient resulting from a decommissioned smelter near Sudbury, and aims to determine the effect of contaminant concentrations (such as soil heavy metals) and environmental variables (such as soil moisture and vegetation cover) on soil microbial populations and diversity. Results suggest that increasing distance from the pollution source did not correlate well with increasing micro-organism population or diversity. Metal concentrations also did not correlate with microbial dynamics. Only soil nutrient abundance showed a significant relationship, and revealed that phosphorous may be the rate-limiting influence. Secondary affects of pollution such as soil erosion and removal of plant litter are suggested to be important causes. The study reinforces the complex nature of landscape scale recovery and shows that recovery pathways are not linear or dependent upon single variables.