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.”

Understanding pollen and spore diversity

November 2, 2012
WDG

Linnean Society Palynology Specialist Group meeting
Linnean Society of London
Burlington House
1st November 2012

Linnean Society (November 2012)

PCRG members at the Linnean Society 1st November
Left-Right: Hayley Keen, William Gosling, Alice Kennedy and Encarni Montoya

Yesterday four members of the Palaeoenvironmental Change Research Group (PCRG) visited the Linnean Society of London to attended the annual palynology meeting. The talks were excellent and covered a wide range of issues in palaynology  from the configuration of Late Triassic Cassopollis grains (Wolfram Kurschner, University of Oslo), through how pollen and spores are built (Stephen Blackmore, Royal Botanic Garderns, Edinburgh) to understanding global patterns of mass-extinctions with particular focus on the Cretaceous-Paleogene (Vivi Vajda, University of Lund). For further information on the days program click here to visit the meeting web site.

The PCRG contribution to the meeting was made by Hayley Keen who presented the first paper related to her doctoral research to an exteral audience entitled “Pollen counting for diverse tropical ecosystems”. The paper presented:  

  1. A statistical model (developed by co-author Felix Hanke) which simulaltes pollen counting in order to estimate the size of pollen count required to develop a robust ecological insight from the fossil pollen record, and
  2. compared model predictions with empirical data from a diverse tropopical ecosystem (Mera, Ecuador) to assess the reliablity of the model.

It is hoped the application of the model to fossil pollen counting will allow more efficient and effective use of palynologists time. The paper was very well recieved despite the audible intake of breath when Hayley recommened that to characterize pollen richness (diversity) in some settings pollen counts in excess of 2000 grains might be required!

Number crunching in palynology

May 10, 2012
HayleyKeen

Simulated pollen counts

Simulated pollen counts

HOW DO WE UNDERSTANT PAST VEGETATION CHANGE?
Our understating of vegetation in the past, and how it has changed through time, comes mainly from the examination of macrofossils (e.g. wood and leaves) and microfossils (e.g. pollen and spores) found in the sedimentary record. The potential for microscopic fossils to provide an insight into past vegetation change on a landscape scale was pioneered by von Post (Von Post, 1916, reprinted 1967) and has been subsequently used to understand changes in regional floras (Godwin, 1956), and address conservation issues (Willis et al., 2007). Analysis of fossil pollen and spores (palynology) is now widely used on late Quaternary timescales to answer ecological questions linking vegetation and wider environmental/climatic change; these include:

  • Has there been a change in major vegetation type (biome)? For example a change between woodlands and grassland vegetation.
  • How have the ecosystem dynamics altered? For example the presence or absence of fire.
  • How has the diversity within the ecosystem changed? For example increase or decrease in sample richness.

Palynological analysis relies on obtaining a sub-sample of the pollen contained within the sediment at a specific depth (time) which allows the vegetation at that time to be reconstructed. This sub-sample is known as a pollen count. To build up a picture of vegetation change through time it is necessary to generate a sequence of pollen counts. The size of the sub-sample (pollen count) required from any particular depth (time period) is dependent on the nature of the vegetation association being investigated and the ecological question being addressed . For example, the amount of pollen analysed to determine if the vegetation was predominantly wooded or grassland is different to that required to provide information on the biological diversity within the vegetation assemblage.

Discussed below are some of the conventions related to choosing an appropriate pollen count size within palynology, with particular reference to the challenges of dealing with diverse tropical floras.

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