Mining in Nunavik puts considerable pressure on the territory, both through its extraction activities and the infrastructure it requires. In this extreme ecosystem, the first organisms to colonize the soil are biocrusts (Williams et al., 2017). Considered the initial stage of terrestrial biome development (Williams et al., 2017), they are also the dominant form of vegetation in polar environments (Belnap et al., 2003). Biocrusts are complex assemblages of living organisms and mineral particles that develop on the surface of the top few millimeters of soil (Williams et al., 2017). They include microscopic organisms (cyanobacteria, algae, fungi, bacteria) as well as macroscopic organisms such as lichens, bryophytes, and various microarthropods.

The overall objective of this master's degree is to study the effect of various disturbances on the biocrusts of northern ecosystems. First, by assessing the impact of proximity to the road on the microbial communities present under the biocrusts, both in terms of diversity and ecological functions. The effect of snow removal will therefore be measured using metagenomic analyses and physicochemical tests. Then, by testing, under controlled conditions, different substrate amendments to assess which ones promote rapid biomass production in biological crusts. To do this, a greenhouse experiment will be conducted using biocrusts collected in Nunavik.

The study site is located near the Nunavik Nickel mining site (61.564426, -73.356810). It is a mine owned by the Canadian Royalties group located north of Pingualuit National Park. 

First, four transects perpendicular to the road were sampled on the side receiving the snow removal. Sampling was carried out on a logarithmic scale (0, 2.5, 5, 10, 20, 40, 80, 160, 320 m). A total of 32 samples were collected from 25 cm × 25 cm quadrats. A rough estimate of the coverage of the quadrats and a soil sample were also collected. This will be used to analyze the pH, conductivity, and the content of nitrogen, phosphorus, potassium of each quadrat.

Secondly, a three-treatment factorial experiment using a completely randomized design was set up. A total of sixty containers filled with coarse rocks, to reproduce the conditions encountered in the field, were placed in a greenhouse. The treatments combine: three ratios of loam addition, two modes of introduction (fragments alone or with the addition of psyllium paste), and two types of biocrusts (dominated by cyanobacteria or Polytrichum sp.). Five replicates per treatment were also set up.

For the first sub-objective, it is expected that there will be a proximity effect on the microbial communities colonizing the soil under the biocrusts (Tian et al., 2023). Indeed, it can be assumed that species more resistant to the effects of snow removal will be observed near the road, while a greater variety of species will be present in quadrats further away (Scott et al., 2025).

For the second sub-objective, it is expected that higher loam addition ratios and the use of biological glue will increase the success rate of biocrust establishment (Mugnai et al., 2024). Furthermore, due to their primary roles in biocrust succession, cyanobacterial crusts are expected to establish more quickly than bryophytes (Chen et al., 2024).

Belnap J, Lange OL, eds. Biological Soil Crusts: Structure, Function, and Management. Vol. 150. Springer; 2003.

Chen R, Yin B, Yang W, et al. Mapping successional stages of biological soil crusts through hydration-induced spectral response. Remote Sens Environ. 2024;310:114230.

Mugnai G, Pinchuk I, Borruso L, et al. Hidden network of biocrust successional stages in the High Arctic. Sci Total Environ. 2024;926:171786.

Tian C, Pang J, Bu C, et al. Microbiomes in lichen and moss biocrusts contribute differently to C and N cycles. Microb Ecol. 2023;86(1):497-508.

Scott B, Zaloumis J, Garcia-Pichel F. Aeolian dust deposition and cyanobacterial community structure in biocrusts. Soil Biol Biochem. 2025;202:109654.

Williams L, Borchhardt N, Colesie C, et al. Biological soil crusts of Arctic Svalbard and Livingston Island. Polar Biol. 2017;40(2):399-411.