Effects of oil sands disturbances on tree structure and composition along Alberta’s boreal forest edges

The boreal forest, resilient to many natural and anthropogenic disturbances, faces significant changes due to forest fragmentation resulting from oil and gas operations. This fragmentation, particularly prominent in Alberta's northeast region, alters forest dynamics and affects wildlife habitat. In this study, we investigated changes in tree structure and composition associated with oil sands footprints on adjacent forest edges.

Specifically, we used a combination of field surveys and Light Detection and Ranging (LiDAR) data to test the influence of disturbance type (gap size), orientation, and distance from forest edges on forest structure and composition. Our study encompasses two disturbance types that vary in gap size: legacy seismic lines and abandoned well pads. For field sites, we examined tree species distribution within different size classes along 100 m-long belt transects perpendicular to forest edges. Paired with these field methods, we used LiDAR to analyze variations in structural patterns for different height strata of forests adjacent to these disturbances. Finally, we assessed whether the abundance of large trees, snags and downed woody debris changes with type and distance from edges. Snags and woody debris are crucial habitats for boreal fauna.

Our findings aim to inform whether and how oil sands disturbances affect boreal forest ecosystems, particularly at forest edges. Determining these effects and the scale of their responses will help guide management practices, restoration, and conservation efforts in the increasingly fragmented oil sands region.