Monthly Archives: August 2013

Blog 3: Environmental transformation of Australia linked to the Late Quaternary demise of the megafauna

Australia provides an outstanding case study to resolve the relationship between Late Quaternary environmental drivers such as climate variability, vegetation changes, wildfires, faunal extinctions and human activities. The interval between 50,000-40,000 years BP is critical for understanding the interplay of some of these factors and how they transformed the Australian landscape. During this period, humans arrived and spread throughout most the continent. At the same time, a diverse range of large browsing mammals, reptiles and birds became extinct; and there is evidence for a marked vegetation change, including more intense and frequent wildfires. Despite this paleo-environmental information, the lack of well dated environmental records has prevented scientists from resolving the relationships between these events.

Tim Flannery was probably the first to propose a causal relationship between the disappearance of great browsing mammals and the increase in fires (1). He suggested the disappearance of the big herbivores was caused by over-hunting, which triggered a massive change in the distribution and structure of plant communities that favoured wildfires, and the extinction of several other smaller animal species. Two recent high-resolution vegetation reconstructions have addressed this hypothesis, providing more detail and support for this theory.

Published last year, a radiocarbon-dated pollen and charcoal profile from northern Australia used changes of the abundance of the fungus spore Sporormiella – a genus of fungi that grows in herbivores dung - as a proxy for large browsing animal activity (2). Between 43,000-38,000 yr BP a succession of environmental changes started with a rapid decline of Sporormiella, followed by an increase in charcoal accumulation and subsequently followed by a decline of rainforest pollen taxa at the expense of grasses and Sclerophyll shrub species. Critically, fire and vegetation changes lagged behind the decline of browsing activity, suggesting that neither of these factors was directly responsible for the faunal extinction. Based on these results, the authors further suggest that the decline in herbivory led to a build up of burnable light fuels and resulted in the increase in wildfires.

A more recent environmental reconstruction from a marine sediment core offshore of southern Australia uses novel proxies for regional vegetation and wildfires over the last 130,000 years (3). Based on biochemical changes in lipids derived from leaf waxes, the regional abundance of C3 and C4 plants is inferred. These two groups of plants have different metabolisms reflecting their preferential distribution over the southern (cold climate with winter precipitation) and northern (warm climate with summer precipitation) parts of the continent respectively. Additionally, paleo-fire activity is inferred from the changes in the accumulation of a biomarker formed during burning and transported offshore by dust and smoke. The record shows how warming periods such as the onset of the present and last interglacial periods are associated with increases in C4 plants, while cooling events such as Last Glacial Maximum are associated with increased C3 plants. However, the most prominent drop in C4 plants between 44,000-42,000 yr BP does not match any climate event. This drastic vegetation transformation is accompanied by high fire activity and occurs right after the interval of disappearance of mega fauna. Similarly, the authors argue for a large-scale ecological transformation caused by the disappearance of large browsers.

These two recent articles provide evidence to support a notable ecosystem rearrangement occurring only after faunal extinction, and not the opposite way around. The implication of this is that hunting was probably the main, if not the only, driver responsible for this extinction process. The disappearance of large herbivores may have promoted the accumulation of fire-prone vegetation, permitting the occurrence and spread of human-lit fires. Further support for a leading role of hunting in the Australian late Quaternary mega fauna extinction come from the fact that other processes of faunal disappearance in the Americas (between 15,000-10,000 yr BP) and New Zealand (750 yr BP) occur coincidently with human colonization of these regions.

1.            T. F. Flannery, Archaeology in Oceania 25, 45 (1990).
2.            S. Rule et al., Science 335, 1483 (March 23, 2012, 2012).
3.            R. A. Lopes dos Santos et al., Nature Geosci 6, 627 (2013).

Australian vegetation

Relative abundance of C4 plant and seasonal precipitation regimes in the Australian Continent. A prominent decreased in C4 plant between 44,000-42,000 yr BP is preceded by the Late Quaternary mega fauna extinction period (49,000-44,000 yr BP). Figure taken from reference Lopes dos Santos et al. (2013).
Diprotodon

Some Australian mega fauna browsers such as the Diprotodon (in the picture) may have weighed up to several tonnes.  Image courtesy of the South Australian Museum

UPDATE: INQUA ECR

AQUA travel awards for the INQUA ECR now due on the 1st October – see previous blog for forms

UPDATE: INQUA 2013 Early Career Researcher Inter-congress meeting:  2nd- 6th December, 2013, Wollongong, New South Wales, Australia. Details attached INQUA 2013 Early Career Researcher Inter-congress meeting:  2nd- 6th December, 2013 for MSc, PhD Candidates and Early Career Researchers

The International Union for Quaternary Research (INQUA) is committed to developing the next generation of Quaternary Scientists. The INQUA Executive Committee has approved the inaugural INQUA Early Career Researcher inter-congress meeting to provide an avenue for MSc/PhD candidates, Post-Doctoral Researchers and research-active academics in the early stage of their careers (within 5 years of obtaining their PhD) to attend valuable workshops designed to assist ECRs with career development, to present their science and gain invaluable mentoring from more senior scientists.

– INQUA Travel Award Applications Due September 1

– Abstracts and Registration Due 1st October

If you intend presenting/poster at the meeting (or applying for the travel prize) or submitting to the Quaternary International Special Issue please use the abstract template you can find this on the FB page https://www.facebook.com/groups/620885067945716/

Please register via the following link: http://www.inqua.org/meetings.html

Quaternary International Special Issue

QI has kindly agreed to run a special issue for ECRs. The aim is for ECRs (MSc/PhD candidates, Post-Doctoral Researchers and research-active academics within 5 years of obtaining their PhD) to either be the primary or single author with manuscripts that are at an advanced stage and ready for submission to the QI editorial process (see attached document for details on how to submit to the Special Issue).

Indication of Submitting for the Quaternary International ECR Special Issue Due Sept 15 and submission via the QI submission process before the meeting (preferably sooner rather than latter so you can get the most out of the review process and writing workshop).

Submissions associated with the commission themes and associated INQUA projects are welcome (http://www.inqua.org/commissions.html).

– Coastal and marine processes [CMP]
– Palaeoclimate [PALCOMM]
– Humans and Biosphere [HaBCom]
– Stratigraphy and Chronology [SACCOM]
– Terrestrial Processes, Deposits and History [TERPRO]

Submissions need to be at the required standard for publication in QI and will undergo the normal QI editorial process. The aim is to have manuscripts submitted before the meeting in December and followed up with writing workshops at the ECR meeting to assist in addressing reviewer’s comments and further developing the manuscripts.

If you have any questions or would like to discuss a submission please contact the Guest Editors of this special Issue Dr. Craig R. Sloss (c.sloss@qut.edu.au<mailto:c.sloss@qut.edu.au>) or Dr. Lynda Petherick (lynda.petherick@qut.edu.au<mailto:lynda.petherick@qut.edu.au>)

Please note: You do not have be attending the meeting to submit to the special issue.

INQUA ECR Student/Postdoc travel award

AQUA is offering two $500 travel prizes to fund attendance for the INQUA ECR inter-congress meeting at the University of Wollongong from the 2-6th of December, 2013. The AQUA prizes are additional to those offered by the meeting organizers, which attendees are also encouraged to apply for.

Download the Austalasian Quaternary Association INQUA ECR travel prize application form

AQUA will award prizes to one student (Masters or PhD) and one early-career post-doc. For consideration of support, applicants must be current members of AQUA, and have submitted an abstract to present either a talk or a poster at the conference. Awards will be granted based on academic merit and the benefit to the recipient.

Please return completed application forms and a copy of the submitted abstract to the AQUA secretary by Monday the 2nd of September. Submissions will be accepted via email

or post:

Duanne White
Institute for Applied Ecology
University of Canberra
Bruce, ACT, 2614

AESC 2014

 

Australian Earth Sciences Convention — AESC   2014
INVITATION TO SUBMIT SESSION PROPOSALS

You have less than 4 weeks to submit your suggestions for   dedicated sessions during the scientific program. Sessions may be in any of   the six general themes (Energy; Resources; Environment; Service and Community; Dynamic Planet; Living Earth). Be quick we want to hear from you.

To propose a session, please provide:
•   A draft title for the session;
•   The theme in which it should appear;
•   Indication whether this is to be an oral session,
a poster-only session, or a poster session supporting an oral session;
•   A one paragraph description outlining the scope of the session;
•   At least three likely presenters
(which may include the session proponents, keynote and invited presenters);
•   A candidate keynote presenter  (optional);
•   An additional candidate invited presenter (optional).

Submit the proposal by e-mail to both of the directors of the Scientific Program,
Bob Musgrave robert.musgrave@industry.nsw.gov.au and
Anthony Dosseto tonyd@uow.edu.au

Posters will be prominently displayed during the conference, and   dedicated poster sessions are strongly encouraged. Poster sessions will be allocated a scheduled time for presenters to explain their work and take   questions.

Please refer to the website www.aesc2014.gsa.org.au or the June 2013 edition of TAG (The Australian Geologist, the newsletter of the Geological Society of Australia)  for detailed descriptions of the themes. You may wish to discuss your   proposal with the convenors of the relevant theme prior to lodging, to   ascertain whether similar or potentially overlapping sessions have already   been planned. In addition to the six themes, the convention will also host   two symposia (39th Symposium on Advances in Study of the Sydney Basin,   and Comparison and Contrasts in Circum-Pacific Orogens).   Proposed sessions should avoid overlap with these symposia.

The theme convenors, together with the 2104 AESC Organising   Committee, will decide the sessions to be accepted before the issuing of the   Call for Abstracts, and will allocate accepted abstracts to sessions.

The deadline for session proposals is 30 August 2013.