University of Alberta research offers new guidance that can help recover habitat for woodland caribou in forests across the province’s Athabasca oilsands region.
The study lays out a strategic method energy companies and provincial land managers can use to determine which seismic lines — narrow clearings cut into the forest for underground petroleum exploration — need human intervention to help regrow trees.
Such restoration can help recover habitat for the caribou, designated as a threatened species.
Knowing which of the tens of thousands of the lines crisscrossing the northern Alberta region need active restoration can help energy companies and land managers best focus their efforts, says study lead Colleen Sutheimer, a PhD candidate in forest biology and management in the Faculty of Agricultural, Life & Environmental Sciences.
“The study provides specific time frames that can be used by decision-makers and land managers to effectively and consistently identify when to let a seismic line regenerate passively — on its own — versus when to spend time and money to intervene.”
Active treatment, which involves mechanically excavating and reshaping soil on seismic lines, then planting trees, “would cost billions of dollars, which has created a need to prioritize planning,” she adds.
The research is the first to explore how long it takes for trees to start growing on Alberta’s seismic lines, known as regeneration lags, and how fast they grow once established, called growth trajectories.
Most prior recovery work has focused on locations where cleared seismic lines fail to regrow trees, but that doesn’t necessarily apply to all lines, notes study co-author Scott Nielsen, a professor of conservation biology.
“A broader assessment of lines shows a diversity of recovery, including places that are naturally recovering and best left for passive management, that also benefit from having no restoration costs,” he says.
“Our work now provides a framework for prioritizing where restoration is really needed and expectations of time to recovery.”
To find out where the forests were recovering sufficiently on their own and which areas needed active treatment, the researchers sampled naturally regenerating trees between 2016 and 2022 on 344 seismic lines that had minimal human disturbance across the oilsands region.
Growth models used in the study showed that generally, trees on seismic lines in boreal upland, or high and hilly forests, can often be left to recover on their own, when further disturbances such as ATV use or re-clearing for continued seismic exploration are limited.
Wildfire was also found to reduce regeneration lag, by stimulating vegetation regrowth in its aftermath.
Based on their findings, the researchers predict that more than 45 per cent of the trees growing on those seismic lines could passively recover to three metres tall— an indicator for forest recovery and the minimum height required by forestry regulations for recovery of caribou habitat in Alberta.
However, in boreal peatland forests — those in wetlands like bogs — the level of passive recovery was predicted to be much lower, at less than one per cent, and could take more than 30 years, due to longer regeneration lags and having slower-growing tree species such as black spruce and tamarack.
Similarly, recovery was forecast to be under 15 per cent for transitional or swampy forests lying between uplands and peatlands.
“The findings suggest that those two forest types could benefit from active restoration treatment, especially through reducing regeneration lags, which ranged from eight to 13 years,” Sutheimer notes.
That said, it’s still unknown whether active treatments would significantly accelerate tree growth enough to warrant the high costs of carrying out restorations across the entire Athabasca oilsands region, the researchers note.
Additionally, given other ecological impacts of active treatments, especially in boreal peatlands, expediting growth may not always be the most beneficial path to recovery, Nielsen says.
“Active treatment requires re-disturbance of seismic lines, which could potentially reset regeneration in all forest types and impact other ecosystem functions and processes,” he adds, noting that further research is underway to answer those questions.
Meanwhile, the researchers have shared the study with industry and government, who have begun using the findings to shape their plans for strategic seismic line recovery, says Sutheimer.
Ultimately, the work will “ensure that across the oilsands region, we are putting more seismic lines on trajectories that will contribute to intact woodland caribou habitat over the next century,” she adds.
The research, part of the Boreal Ecosystem Recovery and Assessment project, was supported by a Natural Sciences and Engineering Research Council of Canada grant in partnership with Alberta-Pacific Forest Industries Inc., Canadian Natural Resources Ltd., Cenovus Energy, ConocoPhillips Canada Resources Corp., Imperial Oil Resources Ltd., Canadian Forest Service’s Northern Forestry Centre and the Alberta Biodiversity Monitoring Institute. Additional funding was provided by the Northern Scientific Training Program administered by Polar Knowledge Canada and the Alberta Conservation Association through its Grants in Biodiversity program.
