Williams PhD thesis 2011

May 13, 2014
WDG

Williams, J.J. (2011) Human and climate impacts on tropical Andean ecosystems. PhD Thesis, Department of Earth & Environmental Sciences, The Open University.

JJW Bolivia (2007)

JJW Bolivia (2007)

Abstract:

Population growth and predicted global climate change are applying new, and increasing, pressure to mountain environments, but the consequences of these changes upon the biodiverse and vulnerable Tropical Andean ecosystems are poorly understood. This thesis explores past human-climate-ecosystem interactions using multi-proxy palaeolimnological investigations (fossil pollen, spore, charcoal and Chironomidae (midges); elemental abundance, colour spectra and magnetic susceptibility) of two sites in the eastern Bolivian Andes (Lake Challacaba and Laguna Khomer Kocha Upper) over the last c. 18,000 years. During the deglaciation and Holocene ecosystems were exposed to varying climatic stress levels, and pressures imposed by the development of human cultures.

Examination of preserved ecological assemblages, including the first assessment of subfossil central Andean Chironomidae, reveals ecosystem sensitivity to changes in temperature, moisture, fire regime, lake level and salinity. Charcoal analysis from Laguna Khomer Kotcha Upper reveals changes in burning at c. 14,500, 10,100 and 6,400 cal yr BP. Concomitant palynological shifts shows this climatically controlled fire regime was a transformative agent of Andean vegetation, particularly for the threatened, high elevation, Polylepis woodlands. Pollen and geochemical data from Lake Challacaba indicate two periods of aridity (c. 4000−3370 and 2190−1020 cal yr BP), these broadly correlated to El Niño/Southern Oscillation variations. Increased Sporormiella abundance after c. 1,340 cal yr BP indicate changes in trade routes and agricultural practices; demonstrating human adaption to environmental change and interconnectivity to Tiwanaku and Inca civilizations.

The long-term response of the terrestrial and aquatic ecosystems, reconstructed from these lakes, has provided insights into how Tropical Andean ecosystems may respond to future changes in temperature, precipitation and human interference. The palaeoenvironmental data has implications for conservation management; it indicates that spatial and temporal variations in site sensitivity, exposure and resilience should be assessed, and that planting strategies should mimic the present day natural patchy distribution of Polylepis woodlands.

Supervisors: Dr. William D. Gosling , Dr. Angela Coe (both The Open University), and Steve Brooks (Natural History Museum).

Examined by: Prof. Henry Hoogheimstra (University of Amsterdam), and Prof. Bob Spicer (The Open University).

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

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Highlights of articles members of the group read recently.

Newspaper articles:

The natural historian faces extinction: Overspecialism and funding cuts could end a vital scientific tradition, claim experts by Joe Kavanagh in The Independent

Fires could turn Amazon rainforest into a desert as human activity and climate change threaten ‘lungs of the world’, says study by Steve Connor in The Independent.

Linked to this article:

Scientific papers:

Giesecke, T., Ammann, B. and Brande, A. (2014) Palynological richness and evenness: insights from the taxa accumulation curve. Vegetation history and archaeobotany. 32, 217 – 228.

SUMMARY (Hayley): “A new method is presented on splitting the log – transformed taxa accumulation curve into sections (natural breaks where the curve deviates from a linear trend), with the hypothesis that breaks in the curve could indicate shifts in abundance between high (e.g. wind pollinated taxa) and low producers of pollen (e.g. insect pollinated taxa), this hypothesis is tested on pollen diagrams from three separate pollen diagrams from varying landscapes.”

Katifori, E., Alben, S., Cerda, E., Nelson, D.R. & Dumais, J. (2010) Foldable structures and the natural design of pollen grains. Proceedings of the National Academy of Sciences of the United States of America, 107, 7635-7639.

SUMMARY (Adele): “This elegant paper highlights the changeability of pollen grains and their responses to their environment, giving those of us who identify pollen based on morphological characteristics plenty to think about.”

Tropical pollen database online

April 7, 2014
WDG

PollenTo facilitate the our ability to identify pollen in the fossil record we have been building a searchable digital tropical pollen database. Our work builds upon the architecture provided by Bush & Weng (2007) for their Neotropical pollen database (Palaeoecology lab, Florida Institute of Technology). We have used Bush & Weng’s freeware tool and expanded it to include an additional 364 pollen and spore types from tropical Africa. The images are of pollen reference material collected over the career of Prof. Dan Livingstone and curated in the Department of Biology, Duke University; full collection details of each specimen are indicated on each individual electronic record. In conjunction with the open access publication “Atlas of the tropical West African pollen flora” (Gosling et al., 2013) we have made the entire updated pollen database available. We hope that this will prove to be a useful tool for palynologists working in Africa and the wider tropics and that it will encourage others to develop the database further.

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Miller PhD thesis 2014

March 26, 2014
lottiemiller

Miller, C.S. (2014) 520,000 years of environmental change in West Africa. PhD Thesis, Department of Environment, Earth & Ecosystems, The Open University.

Lottie 2014

CSM (2014)

Abstract:

Global temperatures are predicted to rise by 2–2.5°C by 2065, profoundly affecting the Earth’s environment. The response of ecosystems to past climate fluctuations can inform on how systems will respond in the future. This thesis focuses on Quaternary environmental changes in West Africa, a region important because of its high ecological value and role in the global carbon cycle.

In 2004, the International Continental Drilling Program recovered c. 291m of sediments spanning the last c. 1 Myr from Lake Bosumtwi (Ghana). Pollen, charcoal and nitrogen isotopes (d15N) were analysed from the most recent c. 150m (c. 520 kyr). The latitudinal position and long duration of this core makes it unique for understanding West African monsoon dynamics and vegetation change.

To aid characterisation of the Bosumtwi pollen succession, an atlas of present-day pollen was constructed for 364 pollen and spore taxa.

The pollen record from Bosumtwi reveals dynamic vegetation change over the last c. 520 kyr, characterized by eleven biome shifts between savannah and forest. Savannah vegetation is dominated by Poaceae (>55%) associated with Cyperaceae, Chenopodiaceae-Amaranthaceae and Caryophyllaceae. Forest vegetation is palynologically diverse, but broadly characterised by Moraceae, Celtis, Uapaca, Macaranga and Trema. Low d15N values correspond to forest expansion and these are driven by high lake levels. The timescale indicates that the six periods of forest expansion correspond to global interglacial periods. The record indicates that the wettest climate occurred during the Holocene, and the driest during Marine Isotope Stage 7.

The vegetation and d15N records show a strong response to glacial-interglacial variability between c. 520–320 kyr and 130–0 kyr. Between c. 320–130 kyr there is a weaker response to glacial-interglacial cycles probably related to high eccentricity during the peak of the 400-kyr component of eccentricity, with high eccentricity resulting in greater seasonality and ultimately drier conditions.

Supervisors: Dr. William Gosling, Dr. Angela Coe (both The Open University) and Dr. Tim Shanahan (University of Texas at Austin)

Examined by: Prof. Henry Lamb (University of Aberystwyth) and Dr. Pallavi Anand (The Open University).

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

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Pollen counting tool

March 21, 2014
WDG

Extracting data from tropical pollen records can be difficult, and time consuming, because of the high floristic diversity. Ecology of the past contributor and PhD researcher Bryan Valencia has developed a method for turning your computer into a tally counter. Bryan’s method allows the easy recording of diverse assemblages, and saves time on data entry. The tally counter can be used to count whatever you like…

Watch the video to find out how:

Use the R-project code below to make it happen.

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PCRG February

March 7, 2014
WDG

William on Bainbridge

My first fieldwork from the OU, in 2005, was pollen trapping on the Galapagos. Here I am looking beardy on Bainbridge.

February was an exciting month for me principally because of the finalization of my move to the University of Amsterdam (UvA) where I will become head of Paleo and Landscape Ecology in September. The decision to leave The Open University (OU) has been a difficult one. When I joined the OU as a RCUK Research Fellow in Ecosystem Science in 2005 I would not have believed that I would be in a position to take on a job such as the one in Amsterdam only nine years later. Building the group here during the last nine years has been a lot of fun and I have got to work with some great people. Stand out moments include:

  • Obtaining my first grant as Principle Investigator (c. US$20,000 from the National Geographic for field work in Bolivia),
  • Recruiting, and graduating, my first PhD research students (Joe Williams and Macarena Cardenas),
  • Being invited to participate in large international research efforts (notably the Lake Bosumtwi project),
  • Co-editing my first book (Bush et al., 2011), having my first student to publish a paper getting it in Science (Cardenas et al., 2011), and helping to write a popular science text co-published by the Natural History Museum (Silvertown et al., 2011)

There have been many more amazing things here but I don’t want to swamp this post with a retrospective of my OU career…

Ongoing excitement within the PCRG is happening on a number of fronts:

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PCRG January

February 12, 2014
WDG

January 2014 has been pretty mad for me but included presenting a poster at the Quaternary Research Association annual meeting, and taking on the role of chair of the British Ecological Society “Eduaction, Training and Careers Committee“.

Tardigrade egg found in Ghanaian pollen trap by Adele

Tardigrade egg found in Ghanaian pollen trap by Adele

Here is a summary of what other people have been up to:

  • Lottie Miller: submission and approval of thesis corrections (hooray), working on British Ecological Society grant application.
  • Hayley Keen: is finishing up lab work (macro charcoal – done, XRF – done, wood macrofossils – thin sectioned, awaiting identification, pollen – just 4 more samples!); and dealing with minor review revisions to first submitted paper (hooray).
  • Frazer Bird: finished the data collection for two Ecuadorian lakes (Banos and Pindo) and will hopefully begin to write up this data soon; attended the NERC stats course (very useful; would advise everyone to try and get on it).
  • Nick Loughlin: has split and logged the sediment cores recovered from Lake Huila (Ecuador) during recent fieldwork, and begun preparing the samples for pollen.
  • Adele Julier: has been preparing pollen trap samples from Ghana and  learning tropical pollen.
  • Emily Sear: has mostly been on holiday and we are still waiting for the post card! She has also been working at getting results that make sense from the MS2.
  • Phil Jardine:   has been oxidising spores to see what it does to the chemistry, generating FTIR data with the oxidised samples and starting the numerical analysis, and editing film footage from the 2013 Ghana trip.
  • Encarni Montoya: has been doing pollen lab and analysing pollen from Baños, and comparing the midges trends from Pindo and Baños with Frazer.
  • Wes Fraser: Reported back to Royal Society on finding from research grant – paper containing exciting results to follow in next couple of months.
Some pollen from Adele's pollen traps in Ghana

Some pollen from Adele’s pollen traps in Ghana

We have also had 4 papers published with 2014 dates on them:

  • Cárdenas, M.L., Gosling, W.D., Pennington, R.T., Poole, I., Sherlock, S.C. & Mothes, P. (2014) Forests of the tropical eastern Andean flank during the middle Pleistocene. Palaeogeography, Palaeoclimatology, Palaeoecology, 393: 76-89. doi: 10.1016/j.palaeo.2013.10.009
  • Fraser, W.T., Watson, J.S., Sephton, M.A., Lomax, B.H., Harrington, G., Gosling, W.D. & Self, S. (2014) Changes in spore chemistry and appearance with increasing maturity. Review of Palaeobotany and Palynology, 201, 41-46. doi:10.1016/j.revpalbo.2013.11.001
  • Miller, C.S. & Gosling, W.D. (2014) Quaternary forest associations in lowland tropical West Africa. Quaternary Science Reviews, 84, 7-25. doi: 10.1016/j.quascirev.2013.10.027
  • Sayer, E.J., Featherstone, H.C. & Gosling, W.D. (2014) Sex & Bugs & Rock n Roll: getting creative about public engagement. Trends in Ecology & Evolution, 29, 65-67. doi: 10.1016/j.tree.2013.12.008

Ecuador Fieldwork : Lake Huila

January 14, 2014
nicholasloughlin

Lake Huila

Lake Huila

So we’re back from a hot and humid Ecuador to the joys of a British winter. Ecuador is an amazing country and the diversity of the flora and fauna surpasses anything that I have experienced before. Continue Reading

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