The methylation of mercury by anaerobic microbes in soils significantly increases its bioaccumulation potential into wildlife. Methylation is counter-acted by demethylation processes, the balance between methylation and demethylation ultimately controlling the amount of methylmercury in a system. Given that microbial activities are intricately linked with temperature, climatic changes should impact mercury methylation and demethylation processes, but the complexity of feedbacks simultaneously occurring between temperature, methylation, and demethylation is not well-characterized in mercury research. Here, we conducted a controlled, growth chamber-based experiment in a closed flow-through system using wetland soils within both harvested and unharvested watersheds across a range of realistic temperatures (5, 10, 15, 20, 25 �C). Mercury methylation (via the 1st-order rate constant Km) and demethylation (via Kd) processes were simultaneously examined in the soil cores using enriched mercury isotope incubations. Our results indicate significantly greater Km in wetland soils within harvested forests compared to those within unharvested forests. In contrast, Kd were nearly identical between harvested and unharvested treatments. Both forest conditions (harvested and unharvested) show a steady increase in Km and Kd activity with increasing temperatures in soil incubation treatments, though the Km increase with warmer temperatures is greater and Kd appears partially threshold driven. This study demonstrates that forest harvesting activity and warmer temperatures in wetland soils both lead to increases in methylation and demethylation rates. Such results highlight the importance of observing the changing climate and management strategies for harvesting activity in the Canadian boreal region due to their effect on mercury cycling in soils.