Peatlands promote fire refugia in boreal forests of northern Alberta, Canada

Abstract In the boreal forests of North America, large wildfires often leave residual patches of unburned vegetation, termed fire refugia, which can affect post‐fire ecosystem processes. Although topographic complexity is a major driver of fire refugia in mountainous terrain, refugia in boreal plain...

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Main Authors: Christine E. Kuntzemann, Ellen Whitman, Diana Stralberg, Marc‐André Parisien, Dan K. Thompson, Scott E. Nielsen
Format: Article
Language:English
Published: Wiley 2023-05-01
Series:Ecosphere
Subjects:
Online Access:https://doi.org/10.1002/ecs2.4510
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author Christine E. Kuntzemann
Ellen Whitman
Diana Stralberg
Marc‐André Parisien
Dan K. Thompson
Scott E. Nielsen
author_facet Christine E. Kuntzemann
Ellen Whitman
Diana Stralberg
Marc‐André Parisien
Dan K. Thompson
Scott E. Nielsen
author_sort Christine E. Kuntzemann
collection DOAJ
description Abstract In the boreal forests of North America, large wildfires often leave residual patches of unburned vegetation, termed fire refugia, which can affect post‐fire ecosystem processes. Although topographic complexity is a major driver of fire refugia in mountainous terrain, refugia in boreal plains are more likely driven by a combination of other bottom‐up controls on fuel configuration as well as top‐down climate controls. In this study, we investigated the role of hydrological, ecological, and topographic heterogeneity, as well as climate moisture patterns, on the presence of fire refugia in forested upland and peatland ecosystems within Alberta's subhumid boreal forests over a 33‐year (1985–2018) period. Generalized linear models were used to model the probability of refugia in forested stands as a function of bottom‐up (vegetation, topography, site moisture, and ecosystem) and top‐down (normal and annual climate moisture deficit) controls. We then developed predictive maps of refugia probability for a range of normal and interannual climate moisture deficit values. We found that forested fens had a probability of refugia that was 64% higher than upland forests, while forested bogs did not differ from forested uplands in refugia likelihood. Climate and physical setting presented the strongest controls on fire refugia in uplands and peatlands, respectively. Increasing amounts of adjacent bogs, but not fens, produced a sixfold increase in refugia probability in uplands, while increasing amounts of adjacent bogs and fens produced roughly two times the refugia probability in forested peatlands. In these upland forest stands, fire refugia probability was negatively related to the interaction between regional climate moisture deficits and interannual deviations from these norms, thus increasing the probability of fire refugia during more severe drought conditions in areas with less arid climates, while decreasing refugia probabilities in drier climates. However, in peatlands themselves, neither regional climate moisture conditions nor the interannual deviations affected refugia. Fire size had a negative effect on fire refugia in all upland‐based models and a positive effect in all peatland‐based models. Our results suggest that large areas of intact peatlands may be capable of promoting fire refugia and thereby slowing climate‐driven, fire‐mediated vegetation transitions in surrounding forest ecosystems.
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spelling doaj.art-0b76117b65774d5598f2313fa5b1f2cf2023-05-30T00:04:33ZengWileyEcosphere2150-89252023-05-01145n/an/a10.1002/ecs2.4510Peatlands promote fire refugia in boreal forests of northern Alberta, CanadaChristine E. Kuntzemann0Ellen Whitman1Diana Stralberg2Marc‐André Parisien3Dan K. Thompson4Scott E. Nielsen5Department of Renewable Resources University of Alberta Edmonton Alberta CanadaNorthern Forestry Centre Canadian Forest Service, Natural Resources Canada Edmonton Alberta CanadaDepartment of Renewable Resources University of Alberta Edmonton Alberta CanadaNorthern Forestry Centre Canadian Forest Service, Natural Resources Canada Edmonton Alberta CanadaGreat Lakes Forestry Centre Canadian Forest Service, Natural Resources Canada Sault Ste. Marie Ontario CanadaDepartment of Renewable Resources University of Alberta Edmonton Alberta CanadaAbstract In the boreal forests of North America, large wildfires often leave residual patches of unburned vegetation, termed fire refugia, which can affect post‐fire ecosystem processes. Although topographic complexity is a major driver of fire refugia in mountainous terrain, refugia in boreal plains are more likely driven by a combination of other bottom‐up controls on fuel configuration as well as top‐down climate controls. In this study, we investigated the role of hydrological, ecological, and topographic heterogeneity, as well as climate moisture patterns, on the presence of fire refugia in forested upland and peatland ecosystems within Alberta's subhumid boreal forests over a 33‐year (1985–2018) period. Generalized linear models were used to model the probability of refugia in forested stands as a function of bottom‐up (vegetation, topography, site moisture, and ecosystem) and top‐down (normal and annual climate moisture deficit) controls. We then developed predictive maps of refugia probability for a range of normal and interannual climate moisture deficit values. We found that forested fens had a probability of refugia that was 64% higher than upland forests, while forested bogs did not differ from forested uplands in refugia likelihood. Climate and physical setting presented the strongest controls on fire refugia in uplands and peatlands, respectively. Increasing amounts of adjacent bogs, but not fens, produced a sixfold increase in refugia probability in uplands, while increasing amounts of adjacent bogs and fens produced roughly two times the refugia probability in forested peatlands. In these upland forest stands, fire refugia probability was negatively related to the interaction between regional climate moisture deficits and interannual deviations from these norms, thus increasing the probability of fire refugia during more severe drought conditions in areas with less arid climates, while decreasing refugia probabilities in drier climates. However, in peatlands themselves, neither regional climate moisture conditions nor the interannual deviations affected refugia. Fire size had a negative effect on fire refugia in all upland‐based models and a positive effect in all peatland‐based models. Our results suggest that large areas of intact peatlands may be capable of promoting fire refugia and thereby slowing climate‐driven, fire‐mediated vegetation transitions in surrounding forest ecosystems.https://doi.org/10.1002/ecs2.4510boreal forestclimatefire refugiapeatlandswildfire
spellingShingle Christine E. Kuntzemann
Ellen Whitman
Diana Stralberg
Marc‐André Parisien
Dan K. Thompson
Scott E. Nielsen
Peatlands promote fire refugia in boreal forests of northern Alberta, Canada
Ecosphere
boreal forest
climate
fire refugia
peatlands
wildfire
title Peatlands promote fire refugia in boreal forests of northern Alberta, Canada
title_full Peatlands promote fire refugia in boreal forests of northern Alberta, Canada
title_fullStr Peatlands promote fire refugia in boreal forests of northern Alberta, Canada
title_full_unstemmed Peatlands promote fire refugia in boreal forests of northern Alberta, Canada
title_short Peatlands promote fire refugia in boreal forests of northern Alberta, Canada
title_sort peatlands promote fire refugia in boreal forests of northern alberta canada
topic boreal forest
climate
fire refugia
peatlands
wildfire
url https://doi.org/10.1002/ecs2.4510
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