Seismic line disturbances affect spatial and temporal patterns of snow accumulation in boreal forests

Geologic exploration for petroleum resources has created a network of linear clearings known as seismic lines in the boreal forest. These anthropogenic disturbances alter the local hydro-climatological conditions within the ecosystems that they cross. However, the effect of seismic lines on wintertime conditions, especially snow accumulation patterns and melt dynamics, remains poorly understood. This study used time lapse photography to investigate whether snowpack conditions were affected by seismic lines by investigating average and maximum snow depth, when the snowpack reaches its maximum depth, when it disappears, and the length of the ablation period. We deployed 50 pairs of cameras (i.e., one on the seismic line, and another in the adjacent area; herein referred to as online and offline, respectively) across two study sites in northern Alberta on seismic lines with different orientations (i.e. E-W, N-S), widths (i.e. <=5 m, >5 m), and ecosite type (i.e. lowland, upland). From the analysis of snow depths between 2017 and 2021, statistically significant differences were observed for maximum snow depth, with the online values being 10% greater than offline. The average snow depth across all images with snow from all locations on the seismic line was 12% higher than offline, but the difference in average snow depth was not statistically significant. The maximum depth of snow on the line was reached five days later than offline and snow-free conditions occurred one day after offline, despite the greater maximum snow depth on the seismic line. The ablation duration (i.e., time from maximum snow depth to snow-free conditions) online was five days shorter than that offline, indicating faster snow loss on the seismic lines. Our results highlight that seismic line disturbances affect the spatial and temporal patterns of snow accumulation and melt in boreal forests, which will have run-on implications for soil thermal and hydrologic regimes, especially in the spring freshet. These results emphasize the need for research that addresses the larger-scale (i.e., catchment-scale) implications of greater snow accumulation on seismic lines that are prolific in northern Alberta.