DOI: 10.5061/dryad.6djh9w105
title: Biodiversity and Forest structure one year following the 2016 Fort McMurray (Alberta) fire event

description: Exploration practices for oil sands developments in the boreal forest of
 western Canada create a network of thousands of kilometers of linear
 features, particularly seismic lines that dissect these forests posing
 significant environmental challenges. As wildfire is one of the prevalent
 stand-replacing natural disturbances in the Canadian boreal forest, it is
 an important driver of environmental change and stand development that may
 contribute to the mitigation of such linear industrial footprint. Here, we
 evaluate the short-term cumulative (also known as combined) effects of
 seismic lines and wildfire on biodiversity and site conditions. One year
 after the Horse River (Fort McMurray, Alberta) fire event in the spring of
 2016, we compared dissected and undisturbed forests in burned and unburned
 boreal peatlands, assessing changes in overall stand structure and the
 responses of a variety of organisms. Soil moisture was significantly
 higher on seismic lines than in the adjacent forest, suggesting why most
 of the study sites within the fire perimeter showed little evidence of
 burning at the line in relation to the adjacent forest. Low fire severity
 on seismic lines seemed an important driver of local species diversity for
 ants, beetles, spiders, and plants in disturbed peatlands, resulting in
 similar species composition on seismic lines both within and outside the
 burned area, but different assemblages in burned and unburned adjacent
 forests. Our results suggest that fire did not erase seismic lines;
 rather, wildfire might increase the influence of this footprint on the
 recovering adjacent forest. Longer term monitoring will be necessary to
 understand how boreal treed peatlands respond to the cumulative effect of
 wildfire and linear disturbances.
description: Data were collected south of Fort McMurray (Alberta, Canada)
 along the 2016 Horse River wildfire southwest perimeter
 (56°31'33" N, 111°18'10" W) at 15 sites in treed
 peatlands dominated by black spruce (<i>Picea mariana</i>),
 with nine sites within the fire and six sites outside the burned area. All
 sites were dissected by conventional seismic lines, were at least 200 m
 from roads, and were at least 2.4 km from each other to guarantee
 independent samples. At each site, three 50 m transects were run parallel
 to each other within each of three habitat types: one transect along the
 center of the seismic line (“Line”), one transect along the forest edge
 (10 m from the line edge; “Edge”), and one transect in the adjacent forest
 (50 m from the line edge; “Forest”). Both Edge and Forest transects were
 located on the same side of the seismic line, with side selected randomly,
 except for sites in the burned area where only one side was available. A
 sampling point was placed every 10 m along each transect, for a total of
 15 sampling points per site (overall, 225 sampling points). Ground
 dwelling arthropods were collected using one pitfall trap at each sampling
 point (five traps/transect and 15 traps/site). Propylene glycol was used
 as preservative and a square roof of corrugated plastic was suspended on a
 wire over the trap to reduce rain and debris falling into the container.
 Traps were serviced every three weeks from May 20 to September 15
 2017. Vegetation data were collected using a 1 m x 1 m quadrat placed
 adjacent to each pitfall trap. Percent cover of all vascular plant species
 was visually estimated to the nearest 0.1%, from the ground to the
 overstory level. We used 1 m height as the threshold to distinguish
 understory (≤ 1 m) and overstory (&gt; 1 m). Additional variables,
 related to site conditions, were collected at each sampling point,
 including soil moisture and temperature, stem basal area and density from
 tree stems ≥ 1.0 cm in diameter at the base, tree regeneration (&lt;
 1.0 cm in diameter at the base), shrub densities (including assessment of
 density ofbog birch (<i>Betula pumila</i>), Labrador tea
 (<i>Rhododendron groenlandicum</i>) and willows
 (<i>Salix </i>spp.)), downed woody material volume
 and density, percent canopy cover, and relative burn severity.
description: Data are provided as eight tables in separate spreadsheets. The
 first data sheet provides a list of spider, carabid beetle, ant, vascular
 and non-vascular plant species with their corresponding species ID (used
 in the species matrices). There are six data sheets that contain the
 species abundance/percent cover fo the sampled taxa. The first three
 sheets contain standardized abundances (number of individuals per 120 trap
 days) of ground-dwelling spiders, carabid beetles and ants collected at
 each site. The following three sheets contain  the percent cover of
 understory, canopy and non-vascular plants at each site. These data are
 presented as matrices with rows representing habitats (burned and unburned
 seismic lines, forest edges and forest interior) at each site and columns
 representing species (species ID). The last data sheet contains
 information about site conditions and other environmental variables at
 each site.