Assistant Professor Palaeoecology

November 18, 2014
WDG

02_05_2007_AsteraceaeVacancy: Assistant Professor Palaeoecology
(5-year tenure track)

Palaeoecology & Landscape Ecology
Institute of Biodiversity & Ecosystem Dynamics
University of Amsterdam

Closing data: 14 December 2014
Interviews: January 2015

We are looking for an ecologist with experience and interest in long timescales specifically related to one, or more, of the following research areas:

  • the Quaternary (last 2.6 million years);
  • sedimentary archives;
  • application and interpretation of proxy indicators (physical, biological and/or geochemical);
  • novel proxy development;
  • numerical/statistical methods in ecology.

For full details on the position and how to apply click here.
For informal discussion of the position please contact William Gosling.

Current research within the P&L group focuses on examining past environmental change in lake sediments (Yanacocha, Peru)

Current research within the P&L group focuses on examining past environmental change in lake sediments (Photo: Yanacocha, Peru)

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…

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African ecology in context

May 14, 2014
WDG

afqua-logo-header-copy

I am delighted to be organizing a focus session at the first AfQUA meeting. The session seeks to bring together ecologists and palaeoecologists working in Africa. If you are interested in getting involved please contact me (William Gosling) directly. For further information on the conference visit the AfQUA website or twitter feed.

Focus session 1: African ecology in context
The African continent spans over 80 degrees of latitude, nearly 6000 m of altitude and around 30 million km2 consequently it contains a vast array of unique ecosystems. Many of the African ecosystems are under direct pressure from human activity and are threatened by on-going and projected climate change. However, management and conservation of the modern African ecosystems is hampered by a paucity of data on their natural history. Studies of observations of ecosystems spanning >30 years are rare so we are heavily reliant on examination of the fossil record to place modern ecology in a long-term (>50 year) context. Information on past ecosystems can be extracted through the examination of a range of biological indicators (e.g. pollen, carbon isotopes, charcoal) found within marine and lake sediments. However, interpretation of the sediments and the proxies they contain with the ecosystems observed today is challenging because of timescale and interpretation issues. The aim of this session is to bring together modern ecologists and paleo-ecologists working in Africa to present the state-of-the-art understanding of ecosystems past and present, and explore how we can improve understanding of timescales and proxy interpretation to place these threatened ecosystems in context.

The Mighty Midge

May 11, 2012
Fray

Fossil chironomid from the Andes

CHIRONOMIDAE AS A PALAEO-ECOLOGICAL TOOL
Chironomidae is a family of two-winged flies more commonly referred to as non biting midges. This diverse group of insects have been known for a long time to be sensitive environmental indicators. Early research in the field showed that the trophic status of lakes could be classified according to the characteristic chironomid assemblages found within them (Thienemann, 1922). Furthermore the head capsules of the larvae are well preserved within the sedimentary record. As a result palaeolimnological researchers became increasingly interested in the potential for using Chironomids to track the trophic development of a lake through time by examining the changing assemblages within the accumulated sediments. With geographically close lakes displaying significantly different midge faunas the potential for the insects being used as climatic indicators was dismissed and the following hypothesis became established: Chironomid assemblage composition reflects in-lake variables, e.g. lake depth, pH, dissolved oxygen, trophic status and substrate. However work by Walker and Matthews (1989) demonstrated that temperature was by far the most significant variable in controlling the broad scale distribution and abundance of midge fauna.

Walker and Matthews realised the potential for the non biting midge to be used as a palaeoclimatic indicator from two initial observations. Firstly within the fossil records, as climate began warming following the deglaciation of the northern hemisphere, the relative abundance of taxa associated with cold oligotrophic lakes (Heterotrissocladius) abruptly declined. Secondly they noticed the best analogues for late glacial assemblages were found in modern day arctic and alpine settings. Overall Walker and Matthews concluded that the northern limit of temperate taxon was controlled by cold summer air and/or water temperatures. The southern limit of Arctic species was instead driven by cold oxygenated refugia in the profundal zone of deep, temperate lakes. These temperatures were significant with respect to the insect’s life cycles as many species require critical temperature thresholds to complete pupation and emergence stages.

Since the pioneering work of Walker and Matthews (1989) and others the debate linking Chironomids to temperature has raged. Debate has centred upon what controls chironomid distribution and  how suitable, if at all, the insects are in the context of palaeoecological studies. Recently Velle et al. (2010) discussed some key factors which must be considered when working on chironomid based temperature resonstructions.

Below I present some of the debate around the midge-environment-temperature debate; focusing on both midge distribution and identification and the potential of this proxy as a indicator of past environmental and climatic change.

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Thinking about proxies

January 31, 2012
Fray

COMMENT ON DISCUSSION OF PROXIES IN HUNTLEY (2012)
All areas of research have strengths and limitations which are readily acknowledged by the scientists involved. The reconstruction of past climates (palaeoclimates) from biological indicators contained within the fossil record (proxies) presents some specific challenges; for example key limitations might be gaps in a sedimentary sequence or post-depositional degradation of samples. Understanding and interpreting data sets in the face of these challenges require the researcher to develop a wide range of skills. Huntley (2012) focuses upon the uncertainties within palaeoclimate reconstruction which he considers to be “frequently overlooked” (p. 2) by scientists making climate reconstructions from proxy records. Specifically Huntley urges researchers to consider carefully:

  • What a given proxy is actually capable of reconstructing, i.e. what climate variables controls its distribution?
  • What other variables might be influencing the proxy, i.e. could there be multiple influences, might these vary through time?
  • What is the spatial relevance of the proxy, i.e. macro versus micro scale?
  • Can multiple proxies be compared, either within or between sites?

In other words: which and how many climatic variables can be reconstructed form any one aspect of the fossil record?

Below I review and comment on some key arguments made by Huntley (2012) related to the use of proxies in reconstructing palaeoclimates.

REFERENCE
Huntley, B. (2012) Reconstructing palaeoclimates from biological proxies: Some often overlooked sources of uncertainty. Quaternary Science Reviews 31: 1-16.

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