Seismic line impacts on proximal boreal forest and wetland environments in Alberta

Abstract

Seismic lines are corridors cut through forest and wetland land covers for geophysical exploration of oil and gas deposits. Here we present a localised case study of the impacts of seismic lines on proximal boreal forest and wetland ecosystem vegetation structural characteristics. The study concentrates on a relatively undisturbed area of the Oil Sands Region of the Boreal zone in north central Alberta using airborne multi-spectral lidar and publically available geospatial data. The results of this study indicate that significant variations in adjacent forest/wetland edge vegetation structure occur proximal to 30 seismic lines identified within the study area. The variations observed in this area depend on the environmental characteristics of the seismic lines. Often taller trees and greater fractional cover extends to a distance of up to 55 m from the seismic line, especially in land covers adjacent to wider seismic lines. Random forest analysis of spatial correspondence between environmental and proximity-based variability associated with seismic lines indicates that distance, incident radiation and the potential for accumulation of surface water based on local geomorphology (inferred from topographic position) are the most important variables affecting height and fractional cover of proximal vegetation. Combined variables including distance from the seismic line, width of the seismic line, cardinal direction and incident radiation, topographic position and underlying surface geology may be used to predict spatial variability of vegetation height to an accuracy of 70% (adjusted (adj.) R²). From this research, we suggest continued sampling/testing of lidar/high resolution optical imagery and geospatial data to examine the impacts of seismic lines in other parts of the Oil Sands Region using the methods developed in this case study. Reclamation management plans for oil and gas exploration areas should focus on reclaiming wider seismic lines first as these have the greatest impact on proximal ecosystems.

Keywords: Edge effects; Lidar; Linear disturbance; Oil sands; Seismic line; Vegetation structure.