CO2‐induced biochemical changes in leaf volatiles decreased fire‐intensity in the run‐up to the Triassic–Jurassic boundary. Issue 4 (30th June 2022)

• Record Type: Journal Article
• Authors: Baker, Sarah J.; Dewhirst, Rebecca A.; McElwain, Jennifer C.; Haworth, Matthew; Belcher, Claire M.
• Is Part Of: New phytologist. Volume 235:Issue 4(2022)
• Page Start: 1442
• Page End: 1454
• Publication Date: 2022-06-30
• Subjects: CO2‐induced biochemical changes -- fire behaviour -- fire intensity -- leaf volatiles -- lignin content -- Triassic–Jurassic transition; Botany -- Periodicals; 580
• DOI: 10.1111/nph.18299
• Languages: English
• ISSNs: 0028-646X

Abstract

Summary: The Triassic–Jurassic boundary marks the third largest mass extinction event in the Phanerozoic, characterized by a rise in CO2 ‐concentrations from c. 600 ppm to c. 2100–2400 ppm, coupled with a c. 3.0–4.0°C temperature rise. This is hypothesized to have induced major floral turnover, altering vegetation structure, composition and leaf morphology, which in turn are hypothesized to have driven changes in wildfire. However, the effects of elevated CO2 on fuel properties, such as chemical composition of leaves, are also important in influencing fire behaviour, but yet have not been considered. We test this by selecting three Triassic analogue species grown experimentally in different atmospheric compositions, and analyse variations in leaf chemistry, and leaf level flammability. These data were used to inform a fire behaviour model. We find that all three species tested showed a reduction in their volatile component, leading to lower flammability. Accounting for these variations in a model, our results suggest that leaf intrinsic flammability has a measurable impact on modelled fire behaviour. If scaled up to ecosystem level, periods of elevated CO2 may therefore be capable of inducing both biochemical and morphological changes in fuel properties, and thus may be capable of influencing fire behaviour.