General
24 Feb 2011

Oldest dated material from Amazon establishes climate and biodiversity link

Cárdenas at the study site

Cárdenas at the study site

Under embargo until 19:00hrs, Thursday 24 February 2011

Research led by Macarena Cárdenas of The Open University, examines the oldest material ever recovered from the cloud forest in western Amazonia– in a biodiversity hotspot – to be accurately dated. The material is so old that it predates the arrival of humans in South America, so Cárdenas and her colleagues knew they were seeing the impact of natural climate change when they established a link between past global temperature variation and biodiversity change.

William Gosling, Lecturer at The Open University and Cárdenas’ PhD supervisor said: “This study provides the first ever insight into how Amazonian vegetation responded to massive climate changes in the Middle Pleistocene period, hundreds of thousands of years ago. The material pre-dates the arrival of humans in South America so can be considered ‘natural’. It has provided scientific evidence relevant to climatologists, ecologists, evolutionary biologists, policymakers and indeed anyone with an appreciation of wildlife: with global warming we can expect to see dramatic changes in life on Earth.”

The Erazo study site in the Amazon cloud forest has been accurately dated to the Middle Pleistocene geological period (c.350,000 years ago) using a state-of-the-art radioactive method at The Open University*. Dating materials is notoriously challenging and accurate dating is rare, but the method used here has resulted in the most precise dates possible given the nature of the material available. The deposits at Erazo are special because they have provided one of the oldest and most comprehensive insights into vegetation in Amazonia ever obtained. Cárdenas says: “The link between temperature and plant diversity has never been seen before in Amazonia for a time period when there was a guaranteed absence of humans.”

Cárdenas and colleagues’ extensive research of the material covered the examination of volcanic ashes, fossil pollen, wood and charcoal. This revealed three new, key insights into tropical vegetation’s response to past cold and warm periods of global climate:

1. The forest continued to survive under both glacial and interglacial climates, but the make-up of the forest changed considerably in response to global climate change.
2. Fire has been a natural component of the landscape during glacial and interglacial periods, but it was closely linked to volcanic activity, and impact of fires on vegetation was limited.
3. Temperature was the main cause of vegetation and biodiversity change between glacial and interglacial climates.

The unique nature of the sediments discovered at the Erazo study site, the cutting edge techniques employed for analysis and the critical importance of improving the understanding of the Amazonian biodiversity hotspot means this research will be of wide interest to a general scientific audience as well as experts and policymakers around the globe.

The study will also help to inform the broad international research effort reported by the Intergovernmental Panel on Climate Change, which highlighted the tropics and past environmental change as areas of poor understanding in their last report.

The research is published today [24 February 2011] by the journal Science.

* The samples were dated using a state-of-the-art Ar-Ar radioactive technique at The Open University, by co-author Dr Sarah Sherlock. The authors are not aware of any alternative methods which could provide more accurate dates.

Ends

Notes to editors

Media contact: Gemma Bessant (01908 655596/g.l.bessant@open.ac.uk).

Dr William Gosling and Macarena Cárdenas are available for interview.

Images available on request.

Dr Toby Pennington (Royal Botanic Gardens Edinburgh) contributed expertise on tropical botany and ecology.

Dr Patricia Mothes (Instituto Geofísico de la Escuela Politécnica Nacional, Quito) contributed expertise on volcanoes and discovered the Erazo study site.

Funding for the project was provided by: The Open University/Royal Botanic Gardens Edinburgh studentship award for Macarena Cárdenas, The Santander corporate responsibility fund, and a British Ecological Society small ecological project grant.

About The Open University

The Open University is the UK’s largest university and the world leader in distance education, and celebrated its 40th anniversary in 2009. It has more than 200,000 students in over 40 countries. Of these, some 1,300 are postgraduate research students.

Macarena Cárdenas and William Gosling are members of The Open University’s Centre for Earth, Planetary, Space & Astronomical Research (CEPSAR). The strength and excellence of the research supported by the Centre was acknowledged in the UK’s last Research Assessment Exercise (RAE 2008), with 70% of its research deemed internationally excellent and world-leading, achieving 3*/4* rankings. CEPSAR website: http://cepsar.open.ac.uk.

Open Research Online (ORO), the University’s freely accessible repository of research publications, is available at: http://oro.open.ac.uk. ORO has around 35,000 visitors from over 170 different countries each month, and is currently ranked the fourth best higher education repository in the UK by the Registry of Open Access Repositories (ROAR).

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