PCRG October

October 31, 2012
WDG

The back end of September and October has been very busy as I have tried to catch up with the teaching, administration and research activity which somewhat accumulated whilst on field work!

Major tasks have been:
1) the marking and coordination for level 3 Geological Record of Environmental Change (S369) module examination,
2) getting used to my new role as Post Graduate Tutor looking after all things related to a doctoral students in the Department of Environment, Earth & Ecosystems, and
3) trying to find time to finish off three manuscripts for submission!

Other members of the lab have also been busy:
* Encarni has arrived from Valenti Rull‘s lab at the Botanical Institute in Barcelona as a NERC Fellow and is settling in to life in Milton Keynes, more details soon…
* Lottie is getting into data analysis and writing up of the Lake Bosumtwi pollen an N isotope data,
* Natalie is writing, crunching numbers and waiting for a machine to be fixed…
* Bryan is working on gelling biogeographic data together in GIS

Imagae of a Toarcian foraminifera taken by Alice Kennedy facilitated by the new cable which allows our microscope camera to talk to a computer – hooray!

* Hayley has been preparing for talking at the Linnean Society palynology meeting on 1st November “Understanding pollen and spore diversity”, and helping “steal” a microtome for sectoning her wood macrofossils,
* Frazer has started to plot Andean and Amazonian midge distributions against temperature, and
* Alice has been taking photos…

In the midst of all this fun I was sent this great video which brightened my day. I hope you enjoy it as well…

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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