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Using a natural experiment to foresee the fate of boreal carbon stores

journal contribution
posted on 2023-05-20, 18:13 authored by David BowmanDavid Bowman
The boreal forests are one of the largest terrestrial carbon stores on Earth, much of which is contained in deep organic soils. The stores of aboveground and belowground biomass are periodically burned by wildfire, a natural disturbance in the boreal zone. Anthropogenic climate change is leading to larger and more severe fires, raising concerns that the boreal forest could become a carbon source rather than a sink. Quantifying and predicting boreal forest fire-driven carbon dynamics is a major research challenge, hampered by the complexity and spatio-temporal scale of the biogeochemical processes involved. Dieleman et al. (2020) used a natural experimental design to show that the legacy effects of past logging and fire disturbance have strongly contrasting effects on aboveground and belowground carbon losses associated with major wildfires that occurred in 2015 in southern boreal forests in central Saskatchewan, Canada. Their study design controlled for the effects of ecoregion, forest type and topo-edaphic gradients that all affect carbon. Based on these data they estimated the magnitude of carbon emissions from the 2015 fire season in Saskatchewan was 36.3 ± 15.0 Tg C. They drew an analogy with northern boreal forests, positing that in the future these forests may store significantly less carbon because frequent fires will impede forest growth and consume organic soil. Natural experiments, such as that undertaken by Dieleman et al. (2020), are constrained by numerous assumptions and contain statistical uncertainties blunting their capacity to accurately disclose the trajectory of complex ecological systems such as boreal carbon dynamics. Nonetheless, natural experiments are a critical element in Earth System science because they are important for framing questions, refining hypotheses and generating empirical data that can inform and ground in reality other approaches, such as mechanistic biogeochemical models, essential in predicting the fate of global carbon stores like those in the boreal forest.


Publication title

Global Change Biology






School of Natural Sciences


Blackwell Publishing Ltd

Place of publication

9600 Garsington Rd, Oxford, England, Oxon, Ox4 2Dg

Rights statement

Copyright 2020 John Wiley & Sons Ltd

Repository Status

  • Restricted

Socio-economic Objectives

Natural hazards not elsewhere classified

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