Growth rates and ages of some key tree species from subantarctic Auckland and Campbell Islands
Growth rates and ages of some key tree species from subantarctic Auckland and Campbell Islands
Interspecific variation in tree growth rate and maximum age is central to understanding and predicting the dynamics of forest ecosystems. While there are abundant sources of this information for economically important New Zealand timber species and other common tree species, data for trees from subantarctic environments are almost entirely lacking. Here we present measurements of growth from Auckland and Campbell Islands for three species: Metrosideros umbellata (southern rātā; Myrtaceae, n = 1 site), a canopy dominant; Dracophyllum sp. (inaka; Ericaceae, n = 5 sites), a widespread small tree; and Olearia lyallii (tūpare, subantarctic tree daisy; Asteraceae, n = 2 sites), a species native to Snares Island that has naturalised on the Auckland Islands. Our data showed large differences in tree growth rates among and within species across islands. Growth rates varied eight-fold (i.e. from 0.34 mm yr−1 to 2.78 mm yr−1), being greatest in Olearia lyallii, least in Dracophyllum sp. and intermediate in Metrosideros umbellata. Comparisons of the five Dracophyllum sites suggest that these trees experience reduced growth rates and reach older ages when in competition with the bigger southern rātā (M. umbellata) trees, possibly due to the larger southern rātā providing protection from wind-throw. Measurements of resprouted southern rātā trees showed a variable juvenile-phase radial growth rate, highlighting the need for caution in extrapolating the likely ages of bigger trees. Remeasured individuals of Olearia lyallii growing among taller southern rātā trees showed slow growth rates compared to much faster rates seen in a nearby monospecific stand. Overall, the variability in growth seen by all three species illustrates that tree size cannot be used to indicate age in these subantarctic islands.
forest conservation, radiocarbon dating, remote islands, Southern Ocean, southern tree limit, World Heritage Area
Palmer, Jonathan G.
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Turney, Chris S.M.
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Thomas, Zoë A.
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Fenwick, Pavla
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Richardson, Sarah J.
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Wilmshurst, Janet M.
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McGlone, Matt S.
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2023
Palmer, Jonathan G.
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Turney, Chris S.M.
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Thomas, Zoë A.
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Fenwick, Pavla
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Richardson, Sarah J.
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Wilmshurst, Janet M.
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McGlone, Matt S.
b84ad1a5-3a14-4f14-a70f-9ee3e386cb48
Palmer, Jonathan G., Turney, Chris S.M., Thomas, Zoë A., Fenwick, Pavla, Richardson, Sarah J., Wilmshurst, Janet M. and McGlone, Matt S.
(2023)
Growth rates and ages of some key tree species from subantarctic Auckland and Campbell Islands.
New Zealand Journal of Ecology, 47 (1), [3509].
(doi:10.20417/nzjecol.47.3509).
Abstract
Interspecific variation in tree growth rate and maximum age is central to understanding and predicting the dynamics of forest ecosystems. While there are abundant sources of this information for economically important New Zealand timber species and other common tree species, data for trees from subantarctic environments are almost entirely lacking. Here we present measurements of growth from Auckland and Campbell Islands for three species: Metrosideros umbellata (southern rātā; Myrtaceae, n = 1 site), a canopy dominant; Dracophyllum sp. (inaka; Ericaceae, n = 5 sites), a widespread small tree; and Olearia lyallii (tūpare, subantarctic tree daisy; Asteraceae, n = 2 sites), a species native to Snares Island that has naturalised on the Auckland Islands. Our data showed large differences in tree growth rates among and within species across islands. Growth rates varied eight-fold (i.e. from 0.34 mm yr−1 to 2.78 mm yr−1), being greatest in Olearia lyallii, least in Dracophyllum sp. and intermediate in Metrosideros umbellata. Comparisons of the five Dracophyllum sites suggest that these trees experience reduced growth rates and reach older ages when in competition with the bigger southern rātā (M. umbellata) trees, possibly due to the larger southern rātā providing protection from wind-throw. Measurements of resprouted southern rātā trees showed a variable juvenile-phase radial growth rate, highlighting the need for caution in extrapolating the likely ages of bigger trees. Remeasured individuals of Olearia lyallii growing among taller southern rātā trees showed slow growth rates compared to much faster rates seen in a nearby monospecific stand. Overall, the variability in growth seen by all three species illustrates that tree size cannot be used to indicate age in these subantarctic islands.
Text
3509
- Version of Record
More information
Accepted/In Press date: 12 May 2022
e-pub ahead of print date: 22 November 2022
Published date: 2023
Additional Information:
Funding Information:
We wish to express our thanks to the captain and crew of the MV Akademik Shokalskiy and Henk Haazen and Kali Kahn on the Tiama for help in the field. This work was supported by the Australasian Antarctic Expedition 2013–2014, the Australian Research Council (CE170100015; FL100100195,
Funding Information:
FT120100004, and DP130104156) and the University of New South Wales. SJR, JMW and MSM were supported by SSIF funding for Crown Research Institutes from the New Zealand Ministry of Business, Innovation and Employment’s Science and Innovation Group. Research on the New Zealand subantarctic Auckland and Campbell Islands was undertaken under Department of Conservation National Authorisation Numbers 37687-FAU and 39761-RES.
Funding Information:
We wish to express our thanks to the captain and crew of the MV Akademik Shokalskiy and Henk Haazen and Kali Kahn on the Tiama for help in the field. This work was supported by the Australasian Antarctic Expedition 2013–2014, the Australian Research Council (CE170100015; FL100100195, FT120100004, and DP130104156) and the University of New South Wales. SJR, JMW and MSM were supported by SSIF funding for Crown Research Institutes from the New Zealand Ministry of Business, Innovation and Employment’s Science and Innovation Group. Research on the New Zealand subantarctic Auckland and Campbell Islands was undertaken under Department of Conservation National Authorisation Numbers 37687-FAU and 39761-RES.
Keywords:
forest conservation, radiocarbon dating, remote islands, Southern Ocean, southern tree limit, World Heritage Area
Identifiers
Local EPrints ID: 475018
URI: http://eprints.soton.ac.uk/id/eprint/475018
ISSN: 0110-6465
PURE UUID: 402409c1-4fbd-474d-a56a-7e3272cf7c07
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Date deposited: 08 Mar 2023 17:55
Last modified: 18 Mar 2024 04:10
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Contributors
Author:
Jonathan G. Palmer
Author:
Chris S.M. Turney
Author:
Zoë A. Thomas
Author:
Pavla Fenwick
Author:
Janet M. Wilmshurst
Author:
Matt S. McGlone
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