Ludgate PhD thesis 2014

March 15, 2022
WDG

Natalie

Ludgate, N. (2014) Organic matter preserved in cave sediments: A new environmental proxy. PhD thesis, Department of Environment, Earth & Ecosystems, The Open University.

Abstract

Exploring new terrestrial archives to investigate past climate and the resultant impact on ecosystems is key to assessing changing climate within large continents, where major records are limited. This study presents the first comprehensive geochemical investigation of clastic cave sediments, a previously under-explored field, demonstrating the effective use of caves as an environmental archive, and recovering useable records of moisture and vegetation regime within the complicated monsoonal system of South East Asia.

Clastic cave sediments were recovered from a 2.4 m deep archaeological trench covering ~24 ka to ~12 ka within Hang Trõng, Vietnam. Clay mineral, bulk carbon, pollen, terrestrial snail shells and plant-derived lipid biomarkers were analysed to provide a multi-proxy approach. No diagenetic alteration was found below 20 cm despite clay mineral and bulk carbon δ13C analysis demonstrating microbial action and weathering of surface sediments. As previously observed in cave sediments, poor preservation lead to limited pollen recovery, however δ13C values from CSIA and shell carbonate indicates C3 vegetation persisted around the cave during the last glacial maximum.

The time-series δ18O record from recovered shells shows clear fluctuations corresponding to global climatic events including the LGM and Heinrich 1. It is hypothesised that these reflect moisture availability, with heavier isotopic values indicating drier periods. Most higher plant lipid biomarkers provide evidence for a stable forest composition, however a shift in n-alkane lipid from C31 to C27 can also be linked with the Heinrich 1 event. The warm Greenland interstadial 1 event is also expressed within the record by low δ18O shell values attributed to more available moisture and higher bulk δ13C values, which indicate greater micro-organism action.

Hang Trõng’s multi-proxy record adds to a growing body of evidence demonstrating the importance of global teleconections when assessing the impact of climate change on monsoons and local vegetation. The data collected here proves clastic cave sediments can hold valuable climatic proxies; something which is of especial importance as palaeoenvironmental archives rely on limited capture and preservation for long term environmental records.

Supervisors: Dr. Alison Blyth (The Open University/Curtin University), Dr. William D. Gosling , and Dr. Iain Gilmore (both The Open University)

Examined by: Prof. Frank McDermot (University College Dublin), and Dr. Victoria Pearson (The Open University).

To borrow a copy from The Open University Library click here.

DOI: https://doi.org/10.21954/ou.ro.0000ef12

Fields and feasts

July 28, 2017
WDG

If you have exciting new research on past ecological change similar to this please consider submitting it for consideration to be published in Vegetation History & Archaeobotany.

If you have exciting new research on past ecological change please consider submitting it to Vegetation History & Archaeobotany.

Two articles recently published on-line in the journal Vegetation History & Archaebotany (of which I am an Associate Editor) recently caught my attention.These explore:

For more detailed thoughts on these papers read on…

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An interview with Phil Jardine

July 1, 2014
philjardine

Well, we’ve heard from Wes and Adele, and now it’s my turn (Phil Jardine) for a bit of a chat on the “Ecology of the past” YouTube channel. Similar to the previous interview videos, I’m talking about my role on the Bosumtwi pollen chemistry project, and what I’ve done (academically speaking) prior to coming to the Open University. Enjoy!

For more videos check out the “Ecology of the past” YouTube channel.

PCRG September

October 2, 2013
WDG

Section of fossil wood from Ecuador

Section of fossil wood from Ecuador

Having been away for half of the month I asked people to provide a summary of what they have been up to. Here is what they admitted to…

Natalie Ludgate and Lottie Miller have submitted their theses! Well done.

Hayley Keen: “Continual pollen counting, second lot of Argon dating done, and first set of wood macrofossils back and ready for identification!”

Frazer Bird: “At the start of September I began working as a technician as part of Encarni’s project. I am looking at the midges from the core we collected together on our last field trip. Things are going well, although the midges are hard to find in the older sections the preservation in early sequences is great. The resolution of this core looks to be fantastic also so and hopefully we will get some interesting results when we compare all the proxies.   Away fromthe lab I presented at INTECOL 2013 in London, The talk seemed to go down well and was noted as highly commended by the judging panel. Great publicity all round for the midges!!!”

Bryan Valencia: Has been on field work in Peru during this time he presented a talk on climate change to the Asociación para la Conservación de la Cuenca Amazónica, and gave interviews to local journalists and two TV stations. He also collected sediments from two locations, and manged to obtain a new US visa. He is now working on the final stages of submitting his thesis.

Phil Jardine: Phil has been busy ordering in microscopes and other equipment for the Lake Bosumtwi project (the first of which arrived today), and setting up the trip to Ghana that he’ll be going on with new PhD student Adele Julier in late October. He’s also been attempting to learn more about geochemistry, which has proved challenging.

Encarni Montoya:

  • Lake Pindo: We have finally the results of 6 samples radiocarbon dated from NRCF through our collaborator Dr Pauline Gulliver, and we have sent 4 more to “range find” the key interval of interests for the FORSENS project. We have started the midges’ analysis although it seems this going to be focused to the upper 4 meters of sediment. We would like to discern possible preservation issues in tropical records for this proxy. Some samples for a preliminary screening looking for diatoms ahve been collected and sent to the new FORSENS collaborator Teresa Vegas-Vilarrúbia. MS samples have been also collected for the first three drives and we hope to run this analysis next month.
  • Lake Banos: We have started the pollen prep. for the upper section of the record.
  • Management tasks: We are now ready for the tropical record Lake Marcacocha pollen prep., collaborating with an ongoing project lead by Alex Chepstow-Lusty. On a different topic, I have started the organisation of department seminars, so I would like to highlight if you have any potential speaker, please contact me.
  • Publications: a co-authorship in a paper published in Perspectives in Plant Ecology, Evolution and Systematics authored by Valentí Rull and his research group in the Botanical Institute of Barcelona is now available on line (click here)

William Gosling: “I have been promoted to Senior Lecturer (hooray), started work on the new level 2 environmental science module, been working on a new paper from the Erazo study site, and had a holiday!”

PDRA: Past environmental and climate change in West Africa

March 29, 2013
WDG

Full time Post-Doctoral Research Associate, Temporary contract for 36 months, £27,854 – £36,298
Department of Environment, Earth & Ecosystems, Faculty of Science, The Open University

Closing date : 25/04/2013

The PDRA project will descover more about past vegetation and climate change in Lake Bosumtwi (Ghana)

The PDRA project will descover more about past vegetation and climate change in Lake Bosumtwi (Ghana)

We are seeking a PDRA to study past climate and vegetation change in tropical West Africa as part of the NERC-funded “500,000 years of solar irradiance, climate and vegetation changes” project. You will join a multidisciplinary collaborative research team and will work with an international network of project partners. The project will utilise cutting-edge organic geochemical techniques to generate the longest continuous record of fossil pollen chemistry change. The study will build upon previous research into the sediments recovered from Lake Bosumtwi (Ghana). The data generated will shed new light on the role of climate in driving vegetation change in the tropics.

You will already hold a PhD, or be near to completing your PhD, in a relevant scientific discipline with a background in the Earth or Environmental sciences. You must have substantial experience of organic geochemistry or tropical palynology, with well-developed self-management skills and the ability to prioritise effectively.

The PDRA will work with an associated PhD student looking at modern pollen-vegetation relationships in the same region.

The PDRA will work with an associated PhD student looking at modern pollen-vegetation relationships in the same region.

Co-Investigators:
Dr Barry Lomax (University of Nottingham)
Dr Wesley Fraser (Oxford Brookes University)

Project partners:
Prof . Yadvinder Malhi (University of Oxford)
Prof. Mark Sephton (Imperial College London)
Dr Tim Shanahan (University of Texas, Austin)
Dr Stephen Abu-Bredu (Forestry Research Institute of Ghana)

For further particulars click here.
For information on how to apply click here visit The Open University jobs web site.

Associated PhD project.

The PDRA will be part of an international team; partners based at University of Nottingham, Oxford Brooks University, Imperial College London, Oxford University, University of Texas at Austin and the Forestry Research Institute of Ghana

The PDRA will be part of an international team; partners based at University of Nottingham, Oxford Brooks University, Imperial College London, Oxford University, University of Texas at Austin and the Forestry Research Institute of Ghana

Funded PhD studentship: Tropical vegetation, environment and climate

March 21, 2013
WDG

William Gosling

William Gosling pollen trapping in west Africa. A studentship on the new grant will investigate modern pollen-vegeation relationships

Fully funded NERC PhD studentship tied to 500,000 years of solar irradiance, climate and vegetation changes project.
To start October 2013 now avaliable with the Palaeoenvironmental Change Research Group.

Title: Tropical vegetation, environment and climate: The present is the key to the past

Supervisors:
William D. Gosling (The Open University),
Wesley Fraser (Oxford Brookes University),
Barry Lomax (University of Nottingham),
Mark Sephton (Imperial College London) &
Yadvinder Malhi (University of Oxford)

  • Investigate the dynamics of modern tropical forest and savannah ecosystems
  • Training in micro fossil and organic geochemical analysis
  • Develop a comprehensive understanding of modern pollen-vegetation relationships
  • Field work in Ghana, in conjunction with Forestry Research Institute of Ghana

Making pollen traps on field work in Ghana

Making pollen traps on field work in Ghana

Understanding how vegetation responded to past climate change requires the development of well constrained relationships between living floras, environment and climate. This project will help constrain the great uncertainty which exists as to how tropical ecosystems are represented in the fossil record by examining the relationship between modern vegetation and the pollen it produces. The project will analyse modern pollen rain using a combination of traditional microscopic analysis [1] and cutting edge geochemical techniques [2]. We anticipate that the findings will provide new insight into past vegetation and climatic change.

For further information on the project and how to apply see the full advert: NERC PhD advert. Prior to applying please check eligibility for NERC funding by clicking here.

Closing date: 25th April, interviews will be held at The Open University during May.

To find out more about the department, research environment and student life at The Open Univerity visit the Department of Environment, Earth & Ecosystems, the Centre for Earth, Planetry, Space & Astronomical Research (CEPSAR) and OU RocSoc web pages.

Work as part of a larger research team in the UK and abroad.

Work as part of a larger research team in the UK and abroad.

References:

[1] Gosling, W.D., et al., Differentiation between Neotropical rainforest, dry forest, and savannah ecosystems by their modern pollen spectra and implications for the fossil pollen record. Review of Palaeobotany and Palynology, 2009. 153(1-2): p. 70-85.
[2] Lomax, B.H., et al., Plant spore walls as a record of long-term changes in Ultraviolet-B radiation. Nature Geoscience, 2008. 1(9): p. 592-596.

500,000 years of solar irradiance, climate and vegetation changes

February 20, 2013
WDG

William Gosling

William Gosling pollen trapping in west Africa. A studentship on the new grant will investigate modern pollen-vegeation relationships from tropical West Africa.

I am delighted to be able to report that the PCRG has recently obtained a NERC standard grant to investigate “500,000 years of solar irradiance, climate and vegetation changes” (NE/K005294/1).

Investigators on the project are:

Supported by project partners:

Much thanks to the many people who have supported and helped us in the development of this proposal. Now time to do some fun science…

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