Caribou Conservation: Restoring Trees on Seismic Lines in Alberta, Canada

Abstract

Seismic lines are narrow linear (~3–8 m wide) forest clearings that are used for petroleum exploration in Alberta’s boreal forest. Many seismic lines have experienced poor tree regeneration since initial disturbance, with most failures occurring in treed peatlands that are used by the threatened woodland caribou (Rangifer tarandus caribou). Extensive networks of seismic lines, which often reach densities of 40 km/km2, are thought to have contributed to declines in caribou. The reforestation of seismic lines is therefore a focus of conservation. Methods to reforest seismic lines are expensive (averaging $12,500 per km) with uncertainty of which seismic lines need which treatments, if any, resulting in inefficiencies in restoration actions. Here, we monitored the effectiveness of treatments on seismic lines as compared to untreated seismic lines and adjacent undisturbed reference stands for treed peatlands in northeast Alberta, Canada. Mechanical site preparation (mounding and ripping) increased tree density when compared to untreated lines, despite averaging 3.8-years since treatment (vs. 22 years since disturbance for untreated). Specifically, treated lines had, on average, 12,290 regenerating tree stems/ha, which is 1.6-times more than untreated lines (7680 stems/ha) and 1.5-times more than the adjacent undisturbed forest (8240 stems/ha). Using only mechanical site preparation, treated seismic lines consistently have more regenerating trees across all four ecosites, although the higher amounts of stems that were observed on treated poor fens are not significant when compared to untreated or adjacent undisturbed reference stands.

Disturbing to restore? Effects of mounding on understory communities on seismic lines in treed peatlands

“…Thus, while mounding has been shown to improve tree establishment (Lieffers et al 2017;Filicetti et al 2019), we found that it resulted in a loss of bryophyte cover. Bryophyte cover, however, is only one aspect of the bryophyte community.…”

“…More work is needed to examine bryophyte diversity and composition between the three treatments, as well as continued monitoring to determine whether (i) bryophyte cover on the tops of the artificial hummocks will recover, (ii) tree growth is faster on these artificial hummocks, and (iii) the artificial hummocks will cause shifts in understory composition over time. Studies also need to explore differences in recovery along the bog-fen gradient (but see Filicetti et al 2019). Lastly, further research should investigate the effects of mounding on other ecological measures, especially the effects on carbon cycling and hydrological flow, as peatlands play an important role in regulating these (Rydin and Jeglum 2006;Strack et al 2019).…”

“…Mounds were created to be 0.75 m wide, 1 m long, and 0.80 m tall and were placed every 6 m along the seismic lines. For additional details on mounding specifications, see Filicetti et al (2019).…”

“…In this study, we focus on measuring the effectiveness of mounding to restore ground vegetation in wooded moderate-rich fens, where recovery of seismic lines has been shown to be particularly slow (Lee and Boutin 2006;van Rensen et al 2015). While mounding has been shown to have promising effects on tree establishment in peatlands (Lieffers et al 2017;Filicetti et al 2019), the effects on other ecological aspects of peatlandsnotably understory plant communitiesrequires further study. Because low-impact seismic lines have extensive coverage in areas of active exploration for oil sands resources, we will be focusing on the impact of mounding in low-impact seismic lines on the understory vegetation.…”

The Forest Line Mapper: A Semi-Automated Tool for Mapping Linear Disturbances in Forests

“…Given the input CHM, output center lines, and footprint polygons, it is possible to extract a series of attributes that may be useful in classifying and assessing the conditions of linear disturbances. In the context of boreal restoration, line width, orientation, and microtopography can be important factors on the microclimate [13] and growth success of newly planted seedlings [10,66]. Therefore, the FLM attributes center lines with spatial information about their length, bearing, direction, and sinuosity.…”