- Title
- Acacia pendula (Weeping Myall) in the Hunter Valley of New South Wales: early explorers' journals, database records and habitat assessments raise doubts over naturally occurring populations
- Creator
- Bell, Stephen; Driscoll, Colin
- Relation
- Cunninghamia Vol. 14, p. 179-200
- Publisher Link
- http://dx.doi.org/10.7751/cunninghamia.2014.14.009
- Publisher
- Royal Botanic Gardens and Domain Trust
- Resource Type
- journal article
- Date
- 2014
- Description
- Acacia pendula, Weeping Myall, is the most legislatively protected plant species in the New South Wales Hunter Valley, and is also threatened across three other eastern Australian States. Under the NSW Threatened Species Conservation Act 1995 it is listed as an Endangered Population (in the Hunter Valley) and as a component of two Endangered Ecological Communities (one in the Hunter, one elsewhere); it is also listed as a Critically Endangered Ecological Community (in the Hunter Valley) on the Commonwealth Environment Protection and Biodiversity Conservation Act 1999. Given the perceived significance of stands of Acacia pendula in the Hunter Valley, and to ascertain its likely original distribution there, this paper examines the writings of early Australian explorers, herbarium and database records, and habitat attributes across NSW. Quite surprisingly, none of the journals examined, including those of botanist/explorer Allan Cunningham (who originally collected Acacia pendula from the Lachlan River in 1817), Thomas Mitchell or Ludwig Leichhardt, make note of the species for the Hunter Valley. Several explorers do, however, record Acacia pendula regularly (>100 times) across other parts of NSW, Queensland, and South Australia. Historical herbarium and database records show a paucity of records from the Hunter prior to the year 2000, after which a 37-fold increase in observations since 1951 is apparent. For the first 128 years of botanical exploration, 1823 to 1951, there are no validated collections or records of Acacia pendula from the Hunter Valley. The single exception is a specimen collected by Cunningham from 1825 (lodged at Kew, UK), purported to be from 'Hunters River', but which is morphologically different to other collections of Acacia pendula from that time. There is uncertainty over its origins as this collection (not specifically mentioned in Cunningham's journal) is mounted on the same sheet as a specimen from the Lachlan River. It does, however, appear similar in morphology to current day Hunter Valley specimens presently attributed (perhaps incorrectly) to Acacia pendula. Analysis of habitats supporting Acacia pendula in NSW outside of the Hunter show them to differ significantly in geological age, soil type, rainfall and elevation. Collectively, these findings provide a strong circumstantial case that Acacia pendula was absent from the Hunter at the time of European settlement; this has important implications for the conservation and management of Hunter stands. Rather than being a threatened species in the Hunter Valley, it is postulated that Acacia pendula has been intentionally and/or accidentally introduced to the region, and may now be imposing a new and emerging threat to the endangered grassy woodlands and forests there. There is now an urgent need for genetic studies to clarify the origins of the Hunter Valley stands, and to define the taxonomic limits of Acacia pendula and its close relatives. There is also the possibility that a new undescribed taxon may be present in the Hunter Valley population, which will require resolution. It seems more likely, however, that neotony (retention of juvenile features in the adult phase), apomixis (replacement of sexual reproduction by asexual reproduction), and/or vigorous root suckering may be operating on introduced Acacias growing in response to unfavourable habitat within the Hunter Valley.
- Subject
- Acacia pendula; Weeping Myall; Hunter Valley; Critically Endangered Ecological Community
- Identifier
- http://hdl.handle.net/1959.13/1299460
- Identifier
- uon:19881
- Identifier
- ISSN:0727-9620
- Language
- eng
- Full Text
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