Multiple lines of evidence infer centurial-scale habitat change and resilience in a threatened plant species at Mount Dangar, Hunter Valley, New South Wales

Bell, SAJ; Lamrock, P; Haines, HA; Turney, C

Multiple lines of evidence infer centurial-scale habitat change and resilience in a threatened plant species at Mount Dangar, Hunter Valley, New South Wales

Bell, SAJ Lamrock, P Haines, HA Turney, C

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Publisher:: CSIRO Publishing
Publication Type:: Journal Article
Citation:: Australian Journal of Botany, 2022, 70, (6), pp. 432-446
Issue Date:: 2022-09-28

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Field	Value	Language
dc.contributor.author	Bell, SAJ
dc.contributor.author	Lamrock, P
dc.contributor.author	Haines, HA
dc.contributor.author	Turney, C https://orcid.org/0000-0001-6733-0993
dc.contributor.editor	Denham, A
dc.date.accessioned	2023-07-03T05:02:55Z
dc.date.available	2022-08-26
dc.date.available	2023-07-03T05:02:55Z
dc.date.issued	2022-09-28
dc.identifier.citation	Australian Journal of Botany, 2022, 70, (6), pp. 432-446
dc.identifier.issn	0067-1924
dc.identifier.issn	1444-9862
dc.identifier.uri	http://hdl.handle.net/10453/171143
dc.description.abstract	Context: Populations of the threatened plant Acacia dangarensis at Mount Dangar (Hunter Valley, New South Wales) may best be managed by recognising centurial, rather than decadal, change in habitat. Aim: Multiple data sources have been used to explore the hypothesis that above-ground presence of A. dangarensis is driven by centurial-scale cycles in climate (wet-dry phases) and fire. Methods: Current-day floristic composition is contrasted with that documented by pre- and post-1900 botanical explorers for A. dangarensis and the fire-sensitive Callitris glaucophylla. Examination of fire history, oral recollections, rainfall and specimen collection databases, and radiocarbon (14C) and dendrochronological analyses of A. dangarensis have been used to build an ecological history of Mount Dangar. Key results: There is no evidence of A. dangarensis occurring on Mount Dangar between 1825 (the first documented exploration) and 1979 (the first collection). Furthermore, historical wet-dry cycles where sufficient fuel was likely to have accumulated to propagate fire (required for seed germination) infer that the species may have last germinated from the seed bank c. 1730, but senesced prior to 1825. Our results suggest that a major fire during the extremely dry Austral summer of 1957-1958 killed most of the then dominant C. glaucophylla individuals. This fire followed 7-10 years of well above-average rainfall, allowing sufficient fuels to accumulate for fire to heat the soil and again release Acacia seed from dormancy. Conclusions: Long-term resilience in A. dangarensis is highlighted irrespective of fire irregularity and recurrent drought that have occurred over at least the past 195 years. Implications: Centurial-scale cycles in climate and fire appear to drive above-ground presence in this species. When present, occasional fruiting events may be sufficient to maintain the seed bank until suitable climatic conditions again favour a major wildfire event and subsequent seedling recruitment.
dc.language	en
dc.publisher	CSIRO Publishing
dc.relation.ispartof	Australian Journal of Botany
dc.relation.isbasedon	10.1071/BT22036
dc.rights	info:eu-repo/semantics/openAccess
dc.subject	0602 Ecology, 0605 Microbiology, 0607 Plant Biology
dc.subject.classification	Plant Biology & Botany
dc.title	Multiple lines of evidence infer centurial-scale habitat change and resilience in a threatened plant species at Mount Dangar, Hunter Valley, New South Wales
dc.type	Journal Article
utslib.citation.volume	70
utslib.for	0602 Ecology
utslib.for	0605 Microbiology
utslib.for	0607 Plant Biology
pubs.organisational-group	/University of Technology Sydney
pubs.organisational-group	/University of Technology Sydney/DVC (Research)
utslib.copyright.status	open_access	*
dc.date.updated	2023-07-03T05:02:53Z
pubs.issue	6
pubs.publication-status	Published
pubs.volume	70
utslib.citation.issue	6

Abstract:

Context: Populations of the threatened plant Acacia dangarensis at Mount Dangar (Hunter Valley, New South Wales) may best be managed by recognising centurial, rather than decadal, change in habitat. Aim: Multiple data sources have been used to explore the hypothesis that above-ground presence of A. dangarensis is driven by centurial-scale cycles in climate (wet-dry phases) and fire. Methods: Current-day floristic composition is contrasted with that documented by pre- and post-1900 botanical explorers for A. dangarensis and the fire-sensitive Callitris glaucophylla. Examination of fire history, oral recollections, rainfall and specimen collection databases, and radiocarbon (14C) and dendrochronological analyses of A. dangarensis have been used to build an ecological history of Mount Dangar. Key results: There is no evidence of A. dangarensis occurring on Mount Dangar between 1825 (the first documented exploration) and 1979 (the first collection). Furthermore, historical wet-dry cycles where sufficient fuel was likely to have accumulated to propagate fire (required for seed germination) infer that the species may have last germinated from the seed bank c. 1730, but senesced prior to 1825. Our results suggest that a major fire during the extremely dry Austral summer of 1957-1958 killed most of the then dominant C. glaucophylla individuals. This fire followed 7-10 years of well above-average rainfall, allowing sufficient fuels to accumulate for fire to heat the soil and again release Acacia seed from dormancy. Conclusions: Long-term resilience in A. dangarensis is highlighted irrespective of fire irregularity and recurrent drought that have occurred over at least the past 195 years. Implications: Centurial-scale cycles in climate and fire appear to drive above-ground presence in this species. When present, occasional fruiting events may be sufficient to maintain the seed bank until suitable climatic conditions again favour a major wildfire event and subsequent seedling recruitment.

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http://hdl.handle.net/10453/171143