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Environmental controls on stable isotope ratios in New Zealand Podocarpaceae : implications for palaeoclimate reconstruction.

Brett, M.J. and Baldini, J.U.L. and Gröcke, D.R. (2014) 'Environmental controls on stable isotope ratios in New Zealand Podocarpaceae : implications for palaeoclimate reconstruction.', Global and planetary change., 120 . pp. 38-45.

Abstract

Stable isotope ratios of various proxies are widely used for palaeoclimate reconstruction, and it is often assumed that isotope ratios reflect vegetation abundance or type. However, very little research exists on the isotopic equilibration of extant biomes under variable environmental conditions. In this study, carbon and oxygen isotope ratios from leaves of various Podocarpaceae genera, endemic to New Zealand, are linked to environmental parameters from the Land Environments New Zealand model. The dominant influence on stable isotope ratios within the majority of Podocarpaceae studied here is vapour pressure deficit (VPD). A simple latitudinal trend does not exist, and neither temperature nor rainfall (decoupled from VPD) controls the stable isotope ratios. The results suggest that modern spatial heterogeneity in VPD affects the stable isotope values of vegetation, and that historic VPD variability would change the stable isotope ratios of Podocarpaceae without necessitating a change in vegetation type, density, or productivity. This represents an alternative model for temporal isotope change within geochemical proxies and reinforces the need for increased stable isotopic research in modern plant ecosystems to better understand modern, and eventually palaeoclimatic processes affecting the terrestrial biosphere.

Item Type:Article
Keywords:Stable isotopes, New Zealand, Podocarps, Leaves, Environment; modern analogue, Palaeoclimate.
Full text:(AM) Accepted Manuscript
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Status:Peer-reviewed
Publisher Web site:http://dx.doi.org/10.1016/j.gloplacha.2014.05.010
Publisher statement:NOTICE: this is the author’s version of a work that was accepted for publication in Global and Planetary Change. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Global and Planetary Change, 120, September 2014, 10.1016/j.gloplacha.2014.05.010.
Date accepted:27 May 2014
Date deposited:23 January 2015
Date of first online publication:02 June 2014
Date first made open access:No date available

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