Neighboring edges: Interacting edge effects from linear disturbances in treed fens

Abstract

Questions Edge influence on forest biodiversity is an important environmental effect associated with habitat fragmentation, but extrapolating the influence of edges across the broader landscape has been difficult, especially for situations where multiple edges exist in close proximity. We asked whether there were differences in edge effects between two types (3 m vs 8 m width) of low‐severity linear disturbance (seismic lines) and whether there were interactions of edge effects when seismic lines occur in dense networks; that is, do multiple narrow seismic lines have a stronger or weaker edge influence than a single narrow seismic line. Location Treed peatlands in northeastern Alberta, Canada. Methods Seismic lines are created during oil and gas exploration and are responsible for dissection of boreal forests in western Canada. We sampled vascular plants along transects perpendicular to seismic lines in moderate‐rich and poor treed fens. We used the “Randomization Test of Edge Influence” (RTEI) to calculate the magnitude and distance of edge effects and then compared these between narrower (3 m) versus wider (8 m) lines and between single narrow lines versus multiple narrow lines (parallel and ~50 m apart). Results In moderate‐rich fens, we found a positive edge influence on understorey diversity from both wide and narrow seismic lines. We also found a weakening edge interaction on diversity, that is, single narrow seismic lines had a stronger edge influence on diversity than did multiple narrow seismic lines. In treed poor fens, multiple narrow seismic lines had a negative edge effect on tree density, understorey abundance, richness, and composition. In addition, we found strengthening edge interactions in treed poor fens on tree density, graminoid cover, and understorey composition. Conclusions Even narrow linear disturbances, such as seismic lines, can have significant edge effects and these are exacerbated when lines occur in dense networks.

Examining Drivers of Post-Fire Seismic Line Ecotone Regeneration in a Boreal Peatland Environment

“…Finnegan et al [24] and Barber et al [25] found that burned seismic lines were characterized by an open canopy of moss, shrub, and graminoid cover, with a 21%-25% reduction in canopy height compared to adjacent forest plots, while Pinzon et al [27] found increased seedling density in low-severity post-fire seismic lines one year following the Horse River fire, but lower in seismic lines that had not burned. In peatlands adjacent to seismic lines, Echiverri et al [58] found that the edge effects of seismic lines in fens occur within 25 m from the seismic line edge.…”

Blanket bogs exhibit significant alterations to physical properties as a result of temporary track removal or abandonment

“…In some regions of North America, tracks and roads represent the largest form of human disturbance (Jorgenson et al, 2010). Effects may be wide‐ranging: vegetation structure and composition may alter (Dabros et al, 2017; Echiverri et al, 2022; Kemper & Macdonald, 2009; Lampinen et al, 2015; Saraswati, Bhusal, et al, 2020), hydrological function may be impaired (McKendrick‐Smith, 2016; Pilon, 2015; Saraswati, Petrone, et al, 2020), biogeochemical and physical processes may be altered (Saraswati et al, 2023; Saraswati, Bhusal, et al, 2020; Saraswati & Strack, 2019) and enhanced sensitivity to climate change may result (Sengbusch, 2015).…”

An initial assessment of winter microclimatic conditions in response to seismic line disturbance in a forested peatland

“…Slow recovery rates of trees and the colonization of invasive species on seismic lines necessitate the study of the environmental variables impacted by seismic lines to discover drivers of recovery trajectory of the plant community (Echiverri et al, 2022). Previous research has investigated the effect of seismic lines and/or linear disturbances on some pertinent components such as soil moisture and temperature (Dabros et al, 2017), light/solar radiation (Pohlman et al, 2007; Williams & Quinton, 2013), bulk density and volumetric water content of the soil (Davidson et al, 2021), air temperature and vapour pressure deficit (Franklin et al, 2021; Haag & Bliss, 1974; Pohlman et al, 2007) and wind speed (WS) (Burton, 2002, Weiland et al, 2023).…”