Post-fire Recovery of Soil Organic Layer Carbon in Canadian Boreal Forests

Bill, Kristen; Dieleman, Catherine M.; Baltzer, Jennifer L.; Degré-Timmons, Geneviève É.; Mack, Michelle C.; Day, Nicola J.; Cumming, Steven G.; Walker, Xanthe J.; Turetsky, M. R.

doi:10.1007/s10021-023-00854-0

Cited by 3 publications

(1 citation statement)

References 77 publications

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“…“biota”; Jenny, 1994), through determining soil C stock accumulation between disturbance cycles. Approximately 1% of the boreal biome burns every year (Wooster & Zhang, 2004), often resulting in large releases of soil C (Bill et al., 2023; Granath et al., 2021; Shao et al., 2023); however, burning severity and soil C loss shows substantial spatial variation both among and within fires (Pérez‐Izquierdo et al., 2023). In recent decades, boreal fires are becoming more frequent, extensive, and severe because of climate warming and summer drought (Balshi et al., 2009; de Groot et al., 2013; Kasischke & Turetsky, 2006; Turetsky et al., 2011).…”

Section: Introductionmentioning

confidence: 99%

The biological controls of soil carbon accumulation following wildfire and harvest in boreal forests: A review

Gundale,

Axelsson,

Buness

et al. 2024

Global Change Biology

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Boreal forests are frequently subjected to disturbances, including wildfire and clear‐cutting. While these disturbances can cause soil carbon (C) losses, the long‐term accumulation dynamics of soil C stocks during subsequent stand development is controlled by biological processes related to the balance of net primary production (NPP) and outputs via heterotrophic respiration and leaching, many of which remain poorly understood. We review the biological processes suggested to influence soil C accumulation in boreal forests. Our review indicates that median C accumulation rates following wildfire and clear‐cutting are similar (0.15 and 0.20 Mg ha−1 year−1, respectively), however, variation between studies is extremely high. Further, while many individual studies show linear increases in soil C stocks through time after disturbance, there are indications that C stock recovery is fastest early to mid‐succession (e.g. 15–80 years) and then slows as forests mature (e.g. >100 years). We indicate that the rapid build‐up of soil C in younger stands appears not only driven by higher plant production, but also by a high rate of mycorrhizal hyphal production, and mycorrhizal suppression of saprotrophs. As stands mature, the balance between reductions in plant and mycorrhizal production, increasing plant litter recalcitrance, and ectomycorrhizal decomposers and saprotrophs have been highlighted as key controls on soil C accumulation rates. While some of these controls appear well understood (e.g. temporal patterns in NPP, changes in aboveground litter quality), many others remain research frontiers. Notably, very little data exists describing and comparing successional patterns of root production, mycorrhizal functional traits, mycorrhizal‐saprotroph interactions, or C outputs via heterotrophic respiration and dissolved organic C following different disturbances. We argue that these less frequently described controls require attention, as they will be key not only for understanding ecosystem C balances, but also for representing these dynamics more accurately in soil organic C and Earth system models.

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Section: Introductionmentioning

confidence: 99%

The biological controls of soil carbon accumulation following wildfire and harvest in boreal forests: A review

Gundale,

Axelsson,

Buness

et al. 2024

Global Change Biology

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Low-severity fires in the boreal region: reproductive implications for black spruce stands in between stand-replacing fire events

Alfaro-Sánchez,

Johnstone,

Baltzer

2024

Annals of Botany

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Background and Aims Stand-replacing crown fires are the most prevalent type of fire regime in boreal forests in North America. However, a substantial proportion of low-severity fires are found within fire perimeters. Here we aimed to investigate the effects of low-severity fires on the reproductive potential and seedling recruitment in boreal forests stands in between stand-replacing fire events. Methods We recorded site and tree characteristics from 149 trees within twelve sites dominated by mature black spruce [Picea mariana (Mill.) B.S.P.] trees in the Northwest Territories, Canada. The presence of fire-scarred trees supported classification of sites as unburned or affected by low-severity fires in recent history. We used non-parametric tests to evaluate differences in site conditions between unburned and low-severity sites, and mixed effect models to evaluate differences in tree age, size, and reproductive traits among unburned trees and trees from low-severity sites. Key Results Results showed significantly higher density of dead black spruce trees in low-severity sites, and marginally significant higher presence of permafrost. Trees from low-severity fire sites were significantly older, exhibited significantly lower tree growth, and showed a tendency towards a higher probability of cone presence and percentage of open cones compared to trees from unburned sites. Surviving fire-scarred trees affected by more recent low-severity fires showed a tendency towards higher probability of cone presence and cone production. Density of black spruce seedlings significantly increased with recent low-severity fires. Conclusions Trees in low-severity sites appeared to have escaped mortality from up to three fires, as indicated by fire scar records and their older ages. Shallow permafrost at low-severity sites may cause lower flammability, allowing areas to act as fire refugia. Low-severity surface fires temporarily enhanced the reproductive capacity of surviving trees and the density of seedlings, likely as a stress response to the fire event.

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Topography and Wildfire Jointly Mediate Postfire Ecosystem Multifunctionality in a Chinese Boreal Forest

Kong,

Ding,

Cai

et al. 2024

Fire

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Both topography and wildfire can exert significant influences on ecosystem processes and functions during boreal forest successions. However, their impacts on ecosystem multifunctionality (EMF) remain unclear. A mega-fire burned an area of 8700 hectares in the Great Xing’an Mountains in 2000, creating a wide range of fire severity levels across various topographic positions. This provided a unique opportunity to explore the impacts of mixed-severity fire disturbance in boreal forests. We evaluated the effect pathways of wildfire and topography on aboveground multifunctionality (AEMF), soil multifunctionality (SEMF), and overall multifunctionality (OEMF). We found that high-severity burning resulted in lower AEMF, SEMF, and OEMF relative to low-severity burning. Topographic positions significantly influenced SEMF and OEMF, but not AEMF. Specifically, both lower SEMF and OEMF were observed on south-facing slopes. The structure equation model analysis showed that aspect had exerted strong indirect effects on AEMF, SEMF, and OEMF by affecting soil moisture and regenerated tree density (RTD). Fire severity had indirect negative effects on AEMF and OEMF by reducing RTD and on SEMF by reducing soil bacterial diversity and RTD. Our study elucidates the necessity of considering postfire site environments to better manage forest ecosystems and, in turn, promote the rapid recovery of boreal ecosystem functions.

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Post-fire Recovery of Soil Organic Layer Carbon in Canadian Boreal Forests

Cited by 3 publications

References 77 publications

The biological controls of soil carbon accumulation following wildfire and harvest in boreal forests: A review

The biological controls of soil carbon accumulation following wildfire and harvest in boreal forests: A review

Low-severity fires in the boreal region: reproductive implications for black spruce stands in between stand-replacing fire events

Topography and Wildfire Jointly Mediate Postfire Ecosystem Multifunctionality in a Chinese Boreal Forest

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