A vegetation and soils monitoring program was implemented at the Gahcho Kué Mine to test for mine-related changes to vegetation and soils from dust deposition. Besides measuring changes in vegetation and soils, one objective of the study is to inform the Wildlife Effects Monitoring Program with respect to the potential for dust as a mechanism for avoidance of habitats near the Mine by caribou and other wildlife.
Soil properties, plant communities, and dust deposition have been monitored since 2013 with permanent vegetation plots and dust collectors using a gradient study design prior to and during construction and operation of the Mine. A single study area transect was established in a west-southwest direction extending 20 kilometres from the Mine footprint, which was based on the prevailing wind direction and terrain features (i.e., large lakes), and the distribution of the target plant community across the landscape.
Dustfall deposition and associated metals concentrations, and soil moisture and temperature variables are monitored annually. Data on plant species richness and abundance and soil pH and salinity are collected every three years. Analysis of variance was performed to determine if fixed dustfall deposition rates varied among sampling areas, seasons, and years. A repeated measures analysis of variance was used to examine patterns of species abundance (percent cover) and species richness across sampling areas and years.
Although dust deposition has shown increasing trends since the commencement of construction and operation, no effects on vegetation from dust were observed in the current analysis. Metals concentrations in dust were generally below detection limits or in trace amounts, consistent with baseline values, and soil pH and salinity were within baseline values. Minor observed changes in species richness are likely related to natural variation in site conditions among vegetation plots and associated sampling areas, annual variation in climate, surveyor variability, and foraging by caribou and other wildlife. Differences in annual dust deposition rates may be attributed to annual variations in temperature, wind, and rainfall. The results suggest that dust-related changes in vegetation community composition is likely not a factor influencing the avoidance of habitats near the Mine by caribou or other wildlife.