Reduced rainfall drives biomass limitation of long‐term fire activity in Australia’s subtropical sclerophyll forests

Mariani, Michela; Tibby, John; Barr, Cameron; Moss, Patrick; Marshall, Jonathan C.; McGregor, Glenn B.

Abstract

Aim
To understand the long‐term drivers of biomass burning in the sclerophyll‐dominated forests of Australia.
Location
Swallow Lagoon, North Stradbroke Island, Queensland, Australia.
Time period
Last ca. 8 kyr.
Major taxa studied
Eucalyptus sensu lato, Leptospermum and Casuarinaceae.
Methods
High‐resolution pollen and charcoal analyses were undertaken on a ca. 8 kyr sediment record and compared with an independent quantitative precipitation reconstruction inferred from leaf carbon isotopes from the same site. We performed Principal Component Analysis to extract the main vegetation trends around Swallow Lagoon. We then compared vegetation changes to local charcoal records to understand the climate‐vegetation‐fire relationships under different rainfall regimes. The trends in pollen, charcoal and rainfall were analysed using Generalized Additive Models and wavelet coherence.
Results
Relatively high Casuarinaceae pollen abundance and high charcoal influx were found prior to 3.4 ka, during a phase of high rainfall. Between 3.4 and 1.5 ka there was an increase in Leptospermum‐type pollen abundance in concert with a decline in both rainfall and charcoal influx. After 1.5 ka low rainfall was generally maintained and a significant increase in Eucalyptus was detected, along with an increase in microscopic charcoal.
Main conclusions
Our study, from a sclerophyll forest setting that is typical of ~30% of Australia's vegetation, provides a unique example of complex climate‐biomass‐fire feedbacks and highlights biomass limitation of fire activity. High rainfall at Swallow Lagoon is linked to dense Casuarinaceae‐dominated forests and high fire activity prior to 3.4 ka. Between 3.4 and 1.5 ka, a decline in rainfall leads to reduced biomass burning during a phase dominated by shrub communities. After 1.5 ka, a change in fuel type was related to a transition to an open eucalypt forest and greater microscopic charcoal influx.

Citation

Mariani, M., Tibby, J., Barr, C., Moss, P., Marshall, J. C., & McGregor, G. B. (2019). Reduced rainfall drives biomass limitation of long‐term fire activity in Australia’s subtropical sclerophyll forests. Journal of Biogeography, 46(9), 1974-1987. https://doi.org/10.1111/jbi.13628

• Journal Article Type: Article
• Acceptance Date: May 5, 2019
• Online Publication Date: Jun 11, 2019
• Publication Date: Jun 11, 2019
• Deposit Date: Jun 18, 2019
• Publicly Available Date: Jun 12, 2020
• Journal: Journal of Biogeography
• Print ISSN: 0305-0270
• Electronic ISSN: 1365-2699
• Publisher: Wiley
• Peer Reviewed: Peer Reviewed
• Volume: 46
• Issue: 9
• Pages: 1974-1987
• DOI: https://doi.org/10.1111/jbi.13628
• Keywords: Ecology; Ecology, Evolution, Behavior and Systematics
• Public URL: https://nottingham-repository.worktribe.com/output/2201724
• Publisher URL: https://onlinelibrary.wiley.com/doi/full/10.1111/jbi.13628
• Additional Information: This is the peer reviewed version of the following article: Reduced rainfall drives biomass limitation of long‐term fire activity in Australia’s subtropical sclerophyll forests, Michela Mariani, John Tibby, Cameron Barr, Patrick Moss, Jonathan C. Marshall, Glenn B. McGregor, which has been published in final form at https://doi.org/10.1111/jbi.13628. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions.
• Contract Date: Jun 18, 2019