Shining a light on fossil sunshine

December 15, 2016
WDG

Dr. Phil Jardine

Dr. Phil Jardine

An international team of scientists have reconstructed the longest ever record of past sunshine using pollen trapped in lake sediments collected in Ghana, Africa. The study published today in Scientific Reports enables us to understand past changes in solar input to the global system over the past 140,000 years. Previously we have had to rely upon computer models to mathematically determine past solar inputs to the Earth. “This work really is a first; being able to peer back in time to understand how the Sun has driven our global system over many of thousands of years is a very exciting prospect” said joint-lead author Dr. Phillip Jardine of The Open University.

The Sun is a key component of our natural environment, driving a multitude of processes at Earth’s surface, from photosynthesis generating energy within plants, through to global-scale circulation patterns in our oceans and atmosphere. Understanding more about how the Sun has behaved in the past, and the influence this had on Earth’s environment, will help scientists predict future climate change.

Dr. Jardine used a technique pioneered by one of his co-authors, Dr. Wesley Fraser of Oxford Brookes University, to determine past changes in solar input, specifically changes in ultraviolet (UV) radiation. Plants protect themselves from the harmful nature of ultraviolet radiation by incorporating a number of specific chemical compounds into their tissues that absorb and dissipate the energy of UV radiation. Pollen grains of flowering plants are also provided protection by these UV-absorbing chemicals, thus act as a long-term recorder of ultraviolet radiation from the Sun.

Pollen grains are readily trapped in lake sediments, where they can be preserved for millions of years. By extracting material from Lake Bosumtwi, Ghana, the pollen that was released by flowering plants thousands of years ago can be separated from the lake sediment and chemically analysed for UV-absorbing chemical compounds. It is this chemical signature within the ancient pollen grains that provides us with information about past levels of solar ultraviolet radiation.

“What we present here is a new opportunity to explore how the Earth has changed” said Dr. William Gosling (University of Amsterdam). “I am particularly excited about this because it will means that we can gain a better understanding of why vegetation changed in the past, and consequently this will allow us to anticipate better what the likely impacts of projected future climate change will be.”

This study is available now at www.nature.com/articles/srep39269

Jardine PE, Fraser WT, Lomax BH, Sephton MA, Shanahan TM, Miller CS & Gosling WD (2016) Pollen and spores as biological recorders of past ultraviolet irradiance. Scientific Reports. DOI: 10.1038/srep39269

Ecology of the past on film: Hayley Keen

October 6, 2015
WDG

Whilst conducting her PhD research Hayley Keen helped produced two of short films about her research project Past environmental change on the eastern Andean flank, Ecuador:

  1. on her field work, which was the winning entry into the American Geophysical Union (AGU) student video competition in 2014, and
  2. a presentation summing up her PhD project in just 3 minutes!

First prize in the AGU student video competition (2014)

Three minute thesis (The Open University, 2014)

Follow Hayley’s ongoing research on this blog and on Twitter @Hayley1keen 

Keen PhD Thesis 2015

September 30, 2015
WDG

Hayley Keen getting excited about sediments during fieldwork in Ecuador (2012). Photo: J. Malley

Hayley Keen getting excited about sediments during fieldwork in Ecuador (2012). Photo: J. Malley

Keen, H.F. (2015) Past environmental change on the eastern Andean flank, Ecuador. PhD Thesis, Department of Environment, Earth & Ecosystems, The Open University.

Abstract
The eastern Andean flank of Ecuador (EAF) contains some of the world’s most biodiverse ecosystems. Andean montane forests are threatened due to anthropogenic pressures and both current and projected climate change. This thesis examines the palaeoecological history of two stratigraphic sequences (Mera Tigre West [MTW] and Mera Tigre East [MTE]) obtained from the Ecuadorian modern lower montane forest. The sediments preserved were analysed using eight analytical techniques, allowing an insight into the ecosystem’s potential response to projected changes derived from their past responses. Palaeoecological studies on the EAF are rare, and those that do exist are debated relating to: i) the inference of robust ecological data from pollen records in floristically diverse locations, and ii) the past source area of sediments preserved in fluvially exposed sequences, potentially leading to contamination with older material.

A statistical sub-sampling tool was developed (debate i), capable of producing statistically robust count sizes for each pollen sample; MTW and MTE count sizes ranged from 196-982 showing the diversity within sequences. The depositional environment of MTE was analysed, investigating sediment provenance throughout (debate ii). Results found that large scale volcanic events were critical in the preservation of the sediments, whereas fluvial influence caused a regional sediment source area in the upper stratigraphy, impacting on the palynological interpretation of MTE. Pollen records demonstrated the presence of a diverse vegetation community with no modern analogue at MTE (abundant taxa (>15 %): Hedyosmum, Wettinia, Ilex) and upper montane forest at MTW (Alnus, Hedyosmum, Podocarpus). Fire was not the main driver for the vegetation reassortment at either site (MTW correlation coefficient: -0.37, MTE: 0.16). The two sites have demonstrated the EAF plays host to floristically dynamic ecosystems, susceptible to drivers of change (fire and landscape) and should be considered when predicting the montane forests’ future response to environmental change.

Supervisors: Dr. William D. Gosling (The Open University/University of Amsterdam), Dr. Encarni Montoya and Dr. Sarah Sherlock (both The Open University).
Examiners: Dr. Dunia Urrego (University of Exeter), and Prof. David Gowing (The Open University).
Chair: Dr. Mark Brandon (The Open University).

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

Publications (so far): Continue Reading

Valencia PhD thesis 2014

March 5, 2015
WDG

Bryan-Kuelap-gate-2010-smallValencia Castillo, B.G. (2014) From glacial to modern conditions: Vegetation and climate change under human influence in the Central Andes. PhD Thesis, Department of Environment, Earth & Ecosystems, The Open University.

Abstract
Conservation, restoration and management strategies are employed to maintain Earth’s biological diversity and physical environment to a near “natural” state. However, the concept of “natural” is generally inexact and may include degraded landscapes. In absence of long-term empirical data of natural baselines, impacted assemblages (human altered baselines) could be falsely assumed to be natural and set as conservation or restoration goals. Therefore, the identification of long-term ecological baselines becomes a pressing requirement especially in threatened biodiversity hotspots such as the tropical Andes that were under human pressure for several millennial.

This thesis aims to identify ecological baselines for tropical Andean ecosystems based on multi-proxy palaeoecological reconstructions from three Andean lakes. Trends of vegetation change are used to identify when landscapes became anthropogenic in the Andes. Because vegetation assemblages at c. 10 ka experienced negligible anthropogenic impacts and had modern-like climate condition, this time was considered the most recent period likely to provide insight into natural ecological baseline conditions.

Changes in vegetation assemblages were evaluated over time departing from 10 ka around Miski and Huamanmarca, two sites that remained virtually impervious to human impacts. Baselines in Miski and Huamanmarca drifted continuously over time and showed that baselines are dynamic entities. The vegetation assemblages derived from Miski and Huamanmarca suggest that that human impact was not homogeneous throughout the Andean landscape.

Once baselines were defined it was possible to evaluate if the spatial distribution of Andean woodlands represented by Polylepis was a product of human impacts. A MaxEnt model generated based on 22 modern environmental variables and 13 palaeoecological vegetation reconstructions showed that Polylepis woodlands were naturally fragmented before humans arrived in South America (14 ka). However, the influence of humans during the mid and late Holocene enhanced the patchiness of the forest generating a hyper-fragmented landscape.

Supervisors: Dr. William D. Gosling , Dr. Angela L. Coe (both The Open University) and Prof. Mark B. Bush (Florida Institute of Technology).

Examined by: Dr. Robert Marchant (University of York), and Prof. David Gowing (The Open University).

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

Organisms and environments: Frontiers in palaeoecological technique development

October 16, 2014
WDG

inquaXIX INQUA Congress
NAGOYA, JAPAN 27 July-2 August, 2015

Grass pollen from Lake Bosumwti picked for individual chemical analysis

Grass pollen from Lake Bosumwti picked for individual chemical analysis

Abstract submission is now open for the XIX International Union for Quaternary Research (INQUA) Congress. “Ecology of the past” researchers will be there and are hosting a special session, entitled Organisms and environments: Frontiers in palaeoecological technique development, at which we hope to bring together a wide range of palaeoecologists working on novel proxy development. Members of the “Ecology of the past” group will be showcasing recent findings on the environmental significance of pollen chemistry change through time; linked to the 500,000 years of solar irradiance, climate and vegetation change in tropical West Africa project (Fraser et al., 2014). Please take a look at our session and consider submitting YOUR abstract today!

For information on abstract submission click here. Closing date for abstract submission 20 December 2014.

For further information on our session click here, or “Continue reading” below…

Continue Reading

Teaching in the field: Foundations, feedback and fun

September 16, 2014
WDG

My final teaching job for The Open University was to help deliver the “Sedimentary Rocks & Fossils in the Field” section of the Level 2 Practical Science module (SXG288) offered by the Science Faculty. I have been involved in all three presentations of this section of the SXG288 module, which will now cease to be offered, and a number of other Earth and environmental science residential schools over the last 9 years.

Showing students the rocksHaving the opportunity to engage directly with students and enthuse them face-to-face about the subject I specialise in is a privilege I have gained a lot from. Furthermore, my over-riding impression from the students I have taught is that they feel they benefit greatly from the opportunity to explore first hand the concepts and subjects which they have previously studied in books and online. Based on my experiences on “Sedimentary Rocks and Fossils”, and other modules as both a tutor and a student, I am convinced that to effectively teach geological, geographical, environmental and ecological subjects effectively an element of field-based teaching is required.

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Three new videos on the Ecology of the Past Youtube channel

July 25, 2014
philjardine

We’ve got a bumper crop of palaeoecological film making for you today, with three videos uploaded to our very own ‘Ecology of the Past’ Youtube channel. We’ve got an interview with Will Gosling, talking about the Bosumtwi pollen chemistry project and his own background and career (it’s a timely and somewhat poignant addition to the channel, because this is Will’s last day at The Open University before heading off to Amsterdam). Also posted are research presentations by Frazer Bird and Hayley Keen, which were filmed during the PhD student conference on 21st May. For the first time at the Open University these presentations were carried out in the Three Minute Thesis (3MT®) format.

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