We present the first survey of the vascular flora of Scotty Creek, a peatland-dominated watershed with discontinuous permafrost about 60 km south of Fort Simpson, Northwest Territories (NWT). Of the 140 vascular plant taxa found at Scotty Creek, two are additions to the boreal flora of NWT: Arethusa bulbosa (Dragon’s-mouth, Orchidaceae) and Carex pauciflora (Few-flowered Sedge, Cyperaceae). The occurrence of Arethusa bulbosa extends the known range of this species 724 km to the northwest, making this purportedly eastern American plant almost pan-Canadian. Two other major range extensions (> 200 km) are reported for Carex brunnescens subsp. sphaerostachya (Round-spike Brownish Sedge) and Platanthera dilatata var. dilatata (Tall White Bog Orchid). Furthermore, 15 other rare NWT species are reported, including three species known from a single other locality in the NWT. The flora of Scotty Creek is dominated by circumpolar (55%) and widespread North American (34%) elements. Despite the absence of exposed alkaline rocks and the dominance of deep organic soil almost throughout Scotty Creek, a number of limeindicator plants were found in lakes and minerotrophic wetlands.

The influence of vegetation and microtopography on fine-scale variability of thaw depth is largely unknown but potentially important for improving modeling of ecosystem-permafrost interactions. To elucidate their influence, we measured tree density, shrub cover and cryptogam presence (lichen and bryophyte) on forested permafrost peat plateaus in the discontinuous permafrost zone in the southern Northwest Territories, Canada. Greater tree density was associated with shallower thaw depth (approximately one quarter of the variance), whereas shrub cover had a negligible influence on thaw depth. Cryptogam species influenced thaw depth, with greater thaw depth associated with Sphagnum than with Cladonia (a difference on the order of 10%). Greater thaw depth occurred beneath hummocks than beneath hollows (a difference also on the order of 10%). Together, canopy cover, cryptogam species and microforms contribute to a variation of roughly half the variance in thaw depth in the peat plateau landscape.

Boreal peatlands of Alberta (Canada) are heavily dissected by a large network of linear disturbances, including seismic lines used for Oil and Gas exploration. Edge effects resulting from these linear disturbances can increase their footprint and affect wildlife habitat, including the quality and quantity of plant and lichen forage. In 2012, seismic line restoration became a priority in Alberta, under the realm of restoration of habitat of threatened boreal woodland caribou. More accurate understanding of biotic and abiotic interactions leading to edge effects can be important in choosing appropriate restoration practices and prompting natural regeneration. We assessed the extent of edge effects of seismic lines on the adjacent boreal peatland near Peace River, northwestern Alberta. We compared plant and lichen community composition and environmental conditions on seismic lines and along 22 transects, which extended perpendicularly 75 m into the peatland from both lines edges. Soil moisture and light were higher on the lines, but frozen ground was less frequent than in the adjacent peatland. Seismic lines were also subsided by approximately 1.2 cm. Lichens were less abundant in the 2–25 m zone from the edge—indicating edge effects. On the lines, Sphagnum constituted a nearly 100% cover while lichens, trees, herbs, and other bryophytes were less abundant than in the peatland. We demonstrate how knowledge of edge effects on plants and lichens could be applied in assessing caribou habitat quality based on forage availability and predation risk, and how such knowledge could inform restoration practices of seismic lines in peatlands.

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