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Carbon isotope discrimination in leaves of the broad-leaved paperbark tree, Melaleuca quinquenervia, as a tool for quantifying past tropical and subtropical rainfall

Lookup NU author(s): Professor Andrew HendersonORCiD

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This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License (CC BY-NC 4.0).

Abstract

Quantitative reconstructions of terrestrial climate are highly sought after but rare, particularly in Australia. Carbon isotope discrimination in plant leaves (Δ_leaf) is an established indicator of past hydroclimate because the fractionation of carbon isotopes during photosynthesis is strongly influenced by water stress. Leaves of the evergreen tree Melaleuca quinquenervia have been recovered from the sediments of some perched lakes on North Stradbroke and Fraser Islands, south-east Queensland, eastern Australia. Here, we examine the potential for using M. quinquenervia ∆_leaf as a tracer of past rainfall by analysing carbon isotope ratios (d¹³C) of modern leaves. We firstly assess Δ_leaf variation at the leaf and stand scale and find no systematic pattern within leaves or between leaves due to their position on the tree. We then examine the relationships between climate and Δ_leaf for an 11 year timeseries of leaves collected in litter traps. M. quinquenervia retains its leaves for 1-4 years; thus cumulative average climate data are used. There is a significant relationship between annual mean ∆_leaf and mean annual rainfall of the hydrological year for 1-4 years (i.e. 365-1460 days) prior to leaf fall (r²=0.64, p=0.003, n=11). This relationship is marginally improved by accounting for the effect of pCO₂ on discrimination (r²=0.67, p=0.002, n=11). The correlation between rainfall and Δ_leaf, and the natural distribution of Melaleuca quinquenervia around wetlands of eastern Australia, Papua New Guinea and New Caledonia offers significant potential to infer past rainfall on a wide range of spatial and temporal scales.

Publication metadata

Author(s): Tibby J, Barr C, McInerney FA, Henderson ACG, Leng MJ, Greenway M, Marshall JC, McGregor GB, Tyler JJ, McNeil V

Publication type: Article

Publication status: Published

Journal: Global Change Biology

Year: 2016

Volume: 22

Issue: 10

Pages: 3474-3486

Print publication date: 01/10/2016

Online publication date: 19/04/2016

Acceptance date: 19/02/2016

Date deposited: 05/04/2016

ISSN (print): 1354-1013

ISSN (electronic): 1365-2486

Publisher: Wiley-Blackwell Publishing Ltd.

URL: http://dx.doi.org/10.1111/gcb.13277

DOI: 10.1111/gcb.13277

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