Search

Seismic lines—narrow and straight corridors from which overstory has been removed to allow access for oil and gas exploration—are a major human footprint in the boreal forest of western Canada. With slow to minimal recovery of tree cover along these corridors, seismic lines have become a persistent landscape feature affecting connectivity and habitat quality in forested ecosystems, particularly in wetland areas. Soil mounding is a common ground preparation treatment widely applied along seismic lines, with the expectation that it will enhance tree seedling establishment and improve the return of tree cover to disturbed areas. However, much is still unknown about environmental responses following treatment application. In this study, we compared the ground microtopography in treated and untreated seismic lines, as well as the relative elevation between treated and untreated seismic lines with their adjacent treed peatland. The ground elevation in both treated and untreated sites was significantly lower on seismic lines relative to their adjacent treed peatland, with a greater elevation difference in treated areas. Likewise, ground microtopography was orders of magnitude higher along treated areas compared to the natural variation in the adjacent treed peatland. Given the important changes in relative elevation and topography following treatment application, our results suggest the potential for eventual treatment success may be more unpredictable than expected; this may have critical consequences for other ecological properties beyond the restoration goal of tree establishment and return of tree cover. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Journal of Forest Research is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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, Canada) 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. [ABSTRACT FROM AUTHOR]

• • Bryophytes regenerated well on low impact seismic (LIS) lines in boreal uplands. • • Feathermoss increased on LIS lines over 5 years from 25 % to 90 % • • Vascular plants did not show strong signs of regeneration over 5 years. • • Edge effects into the forest similar for herbaceous plants over 5 years. • • Succession on LIS lines follows unique pattern compared other boreal disturbances. As of the mid-1990 s, low impact seismic (LIS) line construction (<3 m wide) became common practice in western Canada and replaced construction of wider (5–10 m) conventional seismic lines, with the intention of mitigating the known negative environmental impacts (e.g., severe soil damage and minimal vegetation recovery) of these long, narrow corridors used by the Oil and Gas (O&G) industry for exploration. Though the apparent disturbance severity on LIS lines is lower compared to conventional lines and it is expected that succession would proceed more readily towards the conditions resembling pre-disturbance forested state in the upland boreal, there is little scientific evidence that supports this. Here, we assess environmental conditions, successional trajectories and potential edge effects extending into the adjacent forest from the LIS line edges three (2014) and eight (2019) years after their construction in 2011, in the southern upland boreal forest of Swan Hills region in northwestern Alberta, to determine if active restoration measures should be recommended. Soil moisture and light were higher on the lines compared to the adjacent forest. Bryophytes (particularly feathermosses associated with late-succession forests) recovered well within eight years of disturbance (attaining nearly 90 % cover in 2019, from a relatively low cover (∼25 %) on the lines in 2014, compared to ∼ 80–90 % in the adjacent forest in both years), while the shrub and herbaceous layers recovered minimally, and tree species were still mostly absent on these lines. Herbaceous species also had a lower cover in the ∼ 2 m zone away from the line edges compared to the interior 75 m away, indicating edge effects in both years. Our results indicate that LIS lines appear to possess a unique combination of similarities and differences to other common boreal disturbances (fire, harvest), resulting in the equally unique successional trajectories that do not generally follow patterns known to occur in upland boreal forests. Long-term monitoring is imperative to determine whether LIS lines will eventually return to the pre-disturbance conditions or whether human intervention will be required to promote the growth of the canopy cover, especially as they constitute part of the habitat for Woodland caribou, an important threatened wildlife species. [ABSTRACT FROM AUTHOR]

Various effects on plant growth associated with handling or touching plants are well documented from greenhouse and laboratory studies, but are generally unknown or ignored under field conditions. We examined the prevalence of the effects of handling, at levels typical of many ecological experiments, on aboveground biomass and damage by invertebrate herbivores for a total of 16 common species from three plant communities in western Canada. Significant effects of handling were observed in the alpine meadow and grassland, but not in the boreal forest. Handling reduced aboveground biomass and increased the mean intensity of invertebrate leaf damage for most species. A meta-analysis of the relationship between plant traits and response to handling indicated that woody plants and species without strong chemical or conspicuous morphological defenses were most strongly affected. Overall, our results indicate that potentially confounding effects of routinely sampling plants in the field are widespread and merit further investigation. [ABSTRACT FROM AUTHOR]