Raubenheimer, S.L., Simpson, K. orcid.org/0000-0001-6673-227X, Carkeek, R. et al. (1 more author) (2021) Could CO2-induced changes to C4 grass flammability aggravate savanna woody encroachment? African Journal of Range & Forage Science, 39 (1). pp. 82-95. ISSN 1022-0119
Abstract
Fire plays an important role in maintaining the savanna tree-grass balance by limiting the recruitment of heat-sensitive tree seedlings. However, fire behaviour may change under increasing CO2 concentrations, due to altered flammability of the grassy layer. Here, we determined the effect of predicted future CO2 concentrations, and how it interacts with water-availability, on grass flammability and traits influential to flammability, and uncovered the physiological mechanisms underpinning these responses. Using the widespread C4 savanna grass, Themeda triandra, as a model, we found that improved water-use efficiency under elevated CO2 (800 ppm) resulted in a larger (greater aboveground biomass), but wetter (higher moisture content) grass fuel load, that cured at a slower rate under drought conditions. These changes were associated with increased time to ignition, reduced flaming times and reduced predicted rate of spread. We modelled the effect of altered grass flammability on fire behaviour at a national level (South Africa), finding large-scale reductions in fire spread under elevated CO2, mitigating the converse effects of predicted increases in aridity, and marginal increases in fireline intensity. CO2-induced reductions in fire frequency, spread or intensity could have serious implications for savanna vegetation dynamics, possibly exacerbating the woody encroachment already seen in these ecosystems across the world.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2021 NISC (Pty) Ltd. This is an author-produced version of a paper subsequently published in African Journal of Range & Forage Science. Uploaded in accordance with the publisher's self-archiving policy. |
Keywords: | climate change; C4 grasses; elevated CO2; flammability; fire regimes |
Dates: |
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Institution: | The University of Sheffield |
Academic Units: | The University of Sheffield > Faculty of Science (Sheffield) > School of Biosciences (Sheffield) |
Funding Information: | Funder Grant number Natural Environment Research Council NE/T000759/1 |
Depositing User: | Symplectic Sheffield |
Date Deposited: | 06 Dec 2021 10:05 |
Last Modified: | 10 Feb 2023 14:12 |
Status: | Published |
Publisher: | Taylor & Francis (for the National Inquiry Services Centre) |
Refereed: | Yes |
Identification Number: | 10.2989/10220119.2021.1986131 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:181227 |