Growth rates and ages of some key tree species from subantarctic Auckland and Campbell Islands

Palmer, JG; Turney, CSM; Thomas, ZA; Fenwick, P; Richardson, SJ; Wilmshurst, JM; McGlone, MS

Growth rates and ages of some key tree species from subantarctic Auckland and Campbell Islands

Palmer, JG Turney, CSM Thomas, ZA Fenwick, P Richardson, SJ Wilmshurst, JM McGlone, MS

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Publisher:: NEW ZEALAND ECOL SOC
Publication Type:: Journal Article
Citation:: New Zealand Journal of Ecology, 2023, 47, (1)
Issue Date:: 2023-01-01

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Field	Value	Language
dc.contributor.author	Palmer, JG
dc.contributor.author	Turney, CSM
dc.contributor.author	Thomas, ZA
dc.contributor.author	Fenwick, P
dc.contributor.author	Richardson, SJ
dc.contributor.author	Wilmshurst, JM
dc.contributor.author	McGlone, MS
dc.date.accessioned	2024-01-03T23:39:51Z
dc.date.available	2024-01-03T23:39:51Z
dc.date.issued	2023-01-01
dc.identifier.citation	New Zealand Journal of Ecology, 2023, 47, (1)
dc.identifier.issn	0110-6465
dc.identifier.issn	1177-7788
dc.identifier.uri	http://hdl.handle.net/10453/173973
dc.description.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.
dc.language	English
dc.publisher	NEW ZEALAND ECOL SOC
dc.relation.ispartof	New Zealand Journal of Ecology
dc.relation.isbasedon	10.20417/nzjecol.47.3509
dc.rights	info:eu-repo/semantics/closedAccess
dc.subject	0602 Ecology
dc.subject.classification	Ecology
dc.subject.classification	3103 Ecology
dc.title	Growth rates and ages of some key tree species from subantarctic Auckland and Campbell Islands
dc.type	Journal Article
utslib.citation.volume	47
utslib.for	0602 Ecology
pubs.organisational-group	/University of Technology Sydney
pubs.organisational-group	/University of Technology Sydney/DVC (Research)
utslib.copyright.status	closed_access	*
dc.date.updated	2024-01-03T23:39:50Z
pubs.issue	1
pubs.publication-status	Published
pubs.volume	47
utslib.citation.issue	1

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.

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http://hdl.handle.net/10453/173973