With assistance from the Yukon Oil and Gas Branch, EDI Environmental Dynamics Inc. developed and submitted a proposal to the Mining and Petroleum Environmental Research Group (MPERG) to conduct a study of vegetation regeneration on linear developments subject to wildfires, specifically on and in the vicinity of the winter access road leading to test well site K- 58, beginning in the first post-fire growing season. The study site was located in sub-arctic, black spruce (Picea mariana) dominated forest in a zone of continuous permafrost in the area of Eagle Plains, YT. The study examined vegetation composition and abundance, as well as soil and permafrost conditions, in four types of linear disturbances, including: 1) burned 30+ year old seismic lines;
2) a burned one-year-old winter road; 3) the same burned one-year-old winter road constructed on an existing, 30+ year old seismic line, and; 4) unburned 30+ year old seismic lines. A total of 73 (200m2) paired vegetation plots were completed within each of the above linear disturbances and adjacent forests. Overall, the vegetation was highly uniform among all types of linear disturbances and undisturbed sites in the study area. Differences in species composition and abundance were most pronounced between the burned and unburned sites, with a greater number of species present and higher vegetation cover in unburned sites. Of the three types of linear disturbances sampled, the combined disturbance of the burned one year old winter road constructed on a 30+ year old seismic line demonstrated the most notable differences in vegetation composition and abundance in comparison with the adjacent forest. In contrast, species composition and abundance in the burned winter road and burned 30+ year old seismic line were more similar to that in adjacent, burned forests.
No trends in soil moisture were detected among the various disturbance types. Depth to permafrost was slightly lower in all three linear disturbances, but this difference was not significant. Depth of organic soil was significantly lower in the combined disturbance of the burned one year old winter road constructed on a 30+ year old seismic line, and was significantly higher in the burned winter road, when compared to adjacent, burned forests. Moss depth was significantly higher in unburned than burned sites.
In the first post-fire year, this recent burn appears to be the dominant factor affecting vegetation composition and abundance in the study area. Re-vegetation is occurring rapidly on linear disturbances, with the dominant vascular plant species in the unburned, undisturbed forest regenerating across all disturbance types. Because the study was completed in the first post-fire growing season, it was not possible to assess regeneration of black spruce, an important structural species that is not reported to begin to regenerate until several years after a burn. Similarly, it was also not possible to assess lichen re-establishment, an important element of vegetation succession in black spruce forest that also re-establishes later than the first post-fire
growing season. Continued monitoring will be required to understand the longer term response of vegetation to fire in linear disturbances.
