Peatland vegetation response post-fire in a changing climate

Abstract

Peatland communities in western Canada have slowly developed over thousands of years with wildfires being a constant influence on these systems. As fires move through mature peatland communities, the aftermath is an open landscape where pioneer peatland species establish and develop. The open landscape supports the growth of successional species to create a mature forest, which is then ready for the fire interval cycle to continue. Fire cycles have been a constant on the landscape with little disruption; however, as climate change in western Canada has altered precipitation and temperature regimes, typical vegetation succession patterns that establish after peatland fires may be changing. The Chisholm fire of 2001 burned over 116,000 hectares of forest in northern Alberta, with most of the area being peatlands (treed fens). Vegetation surveys were completed throughout 2018 and 2019 within the burned peatlands of the Chisholm area and compared to an unburnt control area to identify species richness, diversity, composition and vegetation trends. I found, within the re-establishing peatland, a healthy, thriving and diverse community that is developing towards a community similar to the offsite mature treed fen. After almost 20 years of recovery, the affected vegetation community is dominated by peatland species. With temperatures and precipitation levels continually changing, the area is at a transition state in which the community may be maintained on the landscape or the area may experience a regime shift to a drier state.