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Late Holocene climate anomaly concurrent with fire activity and ecosystem shifts in the eastern Australian Highlands

Late Holocene climate anomaly concurrent with fire activity and ecosystem shifts in the eastern Australian Highlands
Late Holocene climate anomaly concurrent with fire activity and ecosystem shifts in the eastern Australian Highlands

The alpine area of the Australian mainland is highly sensitive to climate and environmental change, and potentially vulnerable to ecosystem tipping points. Over the next two decades the Australian alpine region is predicted to experience temperature increases of at least 1 °C, coupled with a substantial decrease in snow cover. Extending the short instrumental record in these regions is imperative to put future change into context, and potentially provide analogues of warming. We reconstructed past temperatures, using a lipid biomarker palaeothermometer technique and mercury flux changes for the past 3500 years from the sediments of Club Lake, a high-altitude alpine tarn in the Snowy Mountains, southeastern Australia. Using a multi-proxy framework, including pollen and charcoal analyses, high-resolution geochemistry, and ancient microbial community composition, supported by high-resolution 210Pb and AMS 14C dating, we investigated local and regional ecological and environmental changes occurring in response to changes in temperature. We find the region experienced a general warming trend over the last 3500 years, with a pronounced climate anomaly occurring between 1000 and 1600 cal yrs. BP. Shifts in vegetation took place during this warm period, characterised by a decline in alpine species and an increase in open woodland taxa which co-occurred with an increase in regional fire activity. Given the narrow altitudinal band of Australian alpine vegetation, any future warming has the potential to result in the extinction of alpine species, including several endemic to the area, as treelines are driven to higher elevations. These findings suggest ongoing conservation efforts will be needed to protect the vulnerable alpine environments from the combined threats of climate changes, fire and invasive species.

Australian Alps, Charcoal, Climate change, Ecosystems, GDGT, Mercury, Pollen
0048-9697
Thomas, Zoë A.
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Mooney, Scott
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Cadd, Haidee
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Baker, Andy
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Turney, Chris S.M.
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Schneider, Larissa
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Hogg, Alan
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Haberle, Simon
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Green, Ken
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Weyrich, Laura S.
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Pérez, Vilma
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Moore, Nicole E.
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Zawadzki, Atun
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Kelloway, Sarah J.
abff6b03-9ca0-490c-b5ad-a0fe859d5711
Khan, Stuart J.
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et al.
Thomas, Zoë A.
4b512d3a-3478-4270-9fdd-61256aa640d3
Mooney, Scott
3bbe1af4-84f6-4678-aba6-4f90dd1c8ba2
Cadd, Haidee
76201167-1262-4904-a8d7-d7551fbb1d43
Baker, Andy
ce6949c6-7c5b-4b75-bcf3-a3a403ef04db
Turney, Chris S.M.
5149b57c-77c2-4375-97a2-a4f00aa74d97
Schneider, Larissa
0adc2b5a-ef9e-44d1-a248-660c1f306c6e
Hogg, Alan
11978083-6632-42e2-ac46-4e0f9cd709c9
Haberle, Simon
63670b93-3a59-46ce-92a2-4a7f4a4513d2
Green, Ken
6cc29731-c298-4fbe-a119-304480893ee1
Weyrich, Laura S.
d2468818-de45-48ce-8987-d51886909226
Pérez, Vilma
1ca13fa5-35da-4341-80a5-f3df3bf7f398
Moore, Nicole E.
9f7f5947-cab5-4334-833d-5d9a92294d0b
Zawadzki, Atun
ac9e5e87-48b6-4e7b-9c05-285515e335f7
Kelloway, Sarah J.
abff6b03-9ca0-490c-b5ad-a0fe859d5711
Khan, Stuart J.
5f54f76a-386f-445f-aad2-7cb025260ece

Thomas, Zoë A., Mooney, Scott and Cadd, Haidee , et al. (2022) Late Holocene climate anomaly concurrent with fire activity and ecosystem shifts in the eastern Australian Highlands. Science of the Total Environment, 802, [149542]. (doi:10.1016/j.scitotenv.2021.149542).

Record type: Article

Abstract

The alpine area of the Australian mainland is highly sensitive to climate and environmental change, and potentially vulnerable to ecosystem tipping points. Over the next two decades the Australian alpine region is predicted to experience temperature increases of at least 1 °C, coupled with a substantial decrease in snow cover. Extending the short instrumental record in these regions is imperative to put future change into context, and potentially provide analogues of warming. We reconstructed past temperatures, using a lipid biomarker palaeothermometer technique and mercury flux changes for the past 3500 years from the sediments of Club Lake, a high-altitude alpine tarn in the Snowy Mountains, southeastern Australia. Using a multi-proxy framework, including pollen and charcoal analyses, high-resolution geochemistry, and ancient microbial community composition, supported by high-resolution 210Pb and AMS 14C dating, we investigated local and regional ecological and environmental changes occurring in response to changes in temperature. We find the region experienced a general warming trend over the last 3500 years, with a pronounced climate anomaly occurring between 1000 and 1600 cal yrs. BP. Shifts in vegetation took place during this warm period, characterised by a decline in alpine species and an increase in open woodland taxa which co-occurred with an increase in regional fire activity. Given the narrow altitudinal band of Australian alpine vegetation, any future warming has the potential to result in the extinction of alpine species, including several endemic to the area, as treelines are driven to higher elevations. These findings suggest ongoing conservation efforts will be needed to protect the vulnerable alpine environments from the combined threats of climate changes, fire and invasive species.

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More information

Published date: 1 January 2022
Additional Information: Funding Information: Many thanks to Xianglin Zheng for processing the loss-on-ignition and pollen slides, Yichen Liu for microbial analysis, and Charlotte Cook and Catherine Jex, Geological Survey of Denmark and Greenland (GEUS), Denmark, for sample collection and GDGT measurements. Pb-210 dating was undertaken via ANSTO grant AP12069 to LS. This research was supported by the Australian Research Council (ARC) Centre of Excellence for Australian Biodiversity and Heritage (EpicAustralia.org.au). We thank UNSW for a Faculty Interdisciplinary Research Grant which helped support this work. ZAT is supported by her ARC DECRA Fellowship (DE200100907). We thank three anonymous reviewers for their insightful comments which helped improve the manuscript. Corrigendum: The authors regret that the printed version of the above article contained a transcription error in the m/z 1048 peak area column for the branched GDGTs (Table S2). This error affected the GDGT-inferred summer air temperature presented in Figs. 3, 4 and 5, and some of the calibrations presented Fig. S2. The GDGT-inferred temperatures have been recalculated and are presented below. The authors would like to apologise for any inconvenience caused. The corrected GDGT-inferred summer air temperature (Fig. 3) is largely within the uncertainty of the temperature calibration (2.0 °C RMSE, Pearson et al., 2011). While the pattern of the temperature variations over the last 3500 years remains unchanged, the GDGT-inferred summer air temperature is between 0.4 and 3.3 degrees lower than was originally presented. The interpretations of Thomas et al. (2022) are unaffected, with reconstructed changes in temperature at Club Lake still associated with several other palaeoenvironmental proxies. Section 4.1 “Our reconstruction of MSAT varies between about 13 and 16 °C, and appears to display a long-term increase in temperature averaging ~0.1 °C per century (Fig. 3).” should be “Our reconstruction of MSAT varies between about 10 and 15 °C, and appears to display a long-term increase in temperature averaging ~0.13 °C per century (Fig. 3).” Section 4.2 “The reconstructed temperature of 16.2 ± 1 °C (which is higher than the contemporary Thredbo AWS mean summer temperature) must therefore be treated with caution.” should be “The reconstructed temperature of 15.7 ± 1 °C (which is higher than the contemporary Thredbo AWS mean summer temperature) must therefore be treated with caution.”
Keywords: Australian Alps, Charcoal, Climate change, Ecosystems, GDGT, Mercury, Pollen

Identifiers

Local EPrints ID: 476041
URI: http://eprints.soton.ac.uk/id/eprint/476041
ISSN: 0048-9697
PURE UUID: 77d7f787-1ee9-49e2-85dd-495f852ea6ae
ORCID for Zoë A. Thomas: ORCID iD orcid.org/0000-0002-2323-4366

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Date deposited: 04 Apr 2023 16:59
Last modified: 18 Mar 2024 04:10

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Contributors

Author: Zoë A. Thomas ORCID iD
Author: Scott Mooney
Author: Haidee Cadd
Author: Andy Baker
Author: Chris S.M. Turney
Author: Larissa Schneider
Author: Alan Hogg
Author: Simon Haberle
Author: Ken Green
Author: Laura S. Weyrich
Author: Vilma Pérez
Author: Nicole E. Moore
Author: Atun Zawadzki
Author: Sarah J. Kelloway
Author: Stuart J. Khan
Corporate Author: et al.

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