Cumulative effects of anthropogenic and natural disturbances have become increasingly relevant in the context of biodiversity conservation. Oil and gas (OG) exploration and extraction activities have created thousands of kilometers of linear footprints in boreal ecosystems of Alberta, Canada. Among these disturbances, seismic lines (narrow corridors cut through the forest) are one of the most common footprints and have become a significant landscape feature influencing the maintenance of forest interior habitats and biodiversity. Wildfire is a common stand-replacing natural disturbance in the boreal forest, and as such, it is hypothesized that its effects can mitigate the linear footprint associated with OG exploration, but only a few studies have examined its effectiveness. We studied the short-term (1 year post-fire) response of rove beetle assemblages to the combined effects of wildfire and linear footprint in forest, edge and seismic line habitats at burned and unburned peatlands along the southwest perimeter of the 2016 Horse River wildfire (Fort McMurray). While rove beetle species richness was higher in seismic lines in both burned and unburned habitats compared to the adjacent peatland, diversity was greater only in seismic lines of burned areas. Abundance was lower in the burned adjacent peatland but similarly higher in the remaining habitats. Assemblage composition on seismic lines was significantly different from that in the adjacent forest and edge habitats within both burned and unburned sites. Moreover, species composition in burned seismic lines was different to either unburned lines or burned forest and edge. Euaesthethus laeviusculus and Gabrius picipennis were indicator species of burned line habitats, are sensitive to post-fire landscape and can occupy wet habitats with moss cover more efficiently than when these habitats are surrounded by unburned forest. Although these results are based on short-term responses, they suggest that wildfire did not reduce the linear footprint, and instead, the cumulative effect of these two disturbances had a more complex influence on rove beetle recovery at the landscape level than for other invertebrates. Therefore, continued monitoring of these sites can become useful to evaluate changes over time and to better understand longer-term biodiversity responses to the cumulative effects of wildfire and linear disturbances in boreal treed peatlands, given the long-lasting effect of such disturbances.

This study was conducted along the southwest perimeter of the 2016 Horse River wildfire, south of Fort McMurry, Alberta (56°46′13″ N, 118°22′28″ W). This area included 15 peatland sites within (“Burned”, n=9) and outside the burned area (“Unburned”, n=6). Sites were disturbed by conventional seismic lines that were built 15-20 years prior to the wildfire event. All sites were at least 200 m from roads and were at least 2.4 km from each other. Sites were located in treed peatlands dominated by black spruce (Picea mariana (Miller) Britton, Sterns & Poggenburgh) in the overstory, and sphagnum (Sphagnum L. spp.), bog haircap (Polytrichum stictum Brid.), red-stemmed feathermoss (Pleurozium schreberi (Brid.) Mitt.), sedges (Carex L. spp.), horsetails (Equisetum L. spp.), three-leaved false Solomon’s seal (Maianthemum trifolium (L.) Sloboda), Labrador tea (Rhododendrum greoenlandicum (Oeder) Kron & Jud), cloudberry (Rubus chamaemorus L.), mountain cranberry (Vaccinium vitis-idaea L.), bogbirch (Betula pumila L.), and willows (Salix L. spp.) in the understory. For sites within the fire perimeter, severity of burns was low on seismic lines but severe in both forest and edge habitats. At each site, we installed three parallel 50 m transects, each in one of three habitat types: along the center of the seismic line (“Line” habitat), along the forest edge approximately 10 m from the line (“Edge” habitat), and in the adjacent peatland approximately 50 m from the line (“Forest” habitat). Edge and Forest transects were located on the same side of the seismic line at each site. We collected rove beetles using pitfall traps (1L in volume, 12 cm diameter) dug into the peat with their upper rims leveled with the ground surface. Traps were filled with approximately 200 ml of propylene glycol as a killing agent and preservative, and were covered with a suspended opaque plastic roof to minimize flooding by rainfall and accumulation of debris. Along each transect, we installed five traps every 10 m for a total of 15 traps/site. We collected trap contents at three-week intervals between May 20 and September 15 of 2017. Adult rove beetles were sorted out from the pitfall samples in the laboratory and identified to the species level using relevant taxonomic literature. Specimens in the subfamily Pselaphinae were identified to the genus level since reliable taxonomic keys for local species are not available. Species in the subfamily Aleocharinae were excluded due todifficulties in species-level identification. Voucher specimens are deposited in the Invertebrate Museum at the Northern Forestry Center (Natural Resources Canada – Canadian Forest Service) in Edmonton, Alberta.

Data are provided as four tables in separate spreadsheets. The first data sheet provides the longitude and latitude of research sites across the study area. The second data sheet provides a list of staphylinid species with their corresponding species ID (used in the community table). The third sheet provides the raw  species abundance by date of collection and habitat in long format. The fourth data sheed provides the standardized catches for each species by habitat type in wide format (rows representing habitat types (burned and unburned seismic lines, forest edges and forest interior) at each site and columns representing species (species ID).