Speakers

Mary Edwards (University of Southampton, Southampton)
Adrian Lister (Natural History Museum, London)
Kathy Willis (University of Oxford, Oxford)

 

Why is palaeoecology important?

Palaeoecology is the study of past flora and fauna dynamics. The study of these long-term biosphere changes is now more important than ever, in the face of current climate change projections, to help us tackle issues in:

  • Biodiversity
  • Natural v human disturbance
  • Ecosystem change

 

What have been the major developments in palaeecology?

Iversen was a key figure in the initial developments of palaeoecology, and its application to our understanding of biospheric change. Early work using palaecological approaches largely focused on the large scale changes in the biosphere over glacial-interglacial cycles.

In the 1970s Davis developed this field by highlighting that individual species respond very differently to climate change. There has been an increasing emphasis on the role of small populations and ‘refugia’ in sustaining species diversity in the face of climate changes.

Refugia represent isolated communities of species, which have been marginalised due to climate change in their original habitat range. For example, during the cold stages of the Quaternary, when much of the Eurasian land mass was covered by ice, many of the temperate tree species (such as oaks; beech; and hazel) were driven southwards to the Mediterranean, where they were able to sustain small populations, often in isolated enclaves, until the climate became more favourable at higher latitudes during the next interglacial. Using palaeoecological records (such as pollen and macrofossils from lake sediments and peatlands for example) we can now construct detailed maps of past species migration during the Quaternary.

We can also apply these techniques to the study of Quaternary megafauna. In INSERT YEAR William Boyd Dawkins published on the types of species present during the Quaternary and their habitat range. By the 1960s we had a good handle on the dynamics of Pleistocene fauna. In particular, there have been major advances in the use of biostratigraphy and the use of the ‘mutual climatic range’ (MCR) approach. This was pioneered by the work of Russell Coope and his work on beetle species distribution. This works on the principle that individual species will occupy a particular environmental ‘envelope’ due to their preferred temperature, precipitation, or vegetation tolerances, for example. In a sedimentary sequence, the presence of two beetle species, with overlapping climatic range, will provide an indication of the prevailing environmental conditions at the time of deposition.

In a similar way, there have also been developments in the use of ‘niche models’ where we can establish the known environmental preference of a species, and use this as an indicator of where it is likely to live. We can also do this for palaeoecological records, using fossil assemblages. It is important here to remember that changes in faunal distribution represent a response to environmental change. Using faunal distribution to indicate climate change, and subsequently rationalise faunal response to this change is a circular argument that must be avoided.

We can also use palaeocological records to investigate leads and lags in the earth system. For example, following several decades of work mapping the distribution of mammoth remains across Europe, we now have detailed insights into their migratory patterns since the last glacial maximum, until their final demise in the Holocene when they became extinct. In combination with wider terrestrial records, including detailed pollen records, we can place their population dynamics into a wider context of Quaternary environmental change. It is now thought that a major eastward shift in their distribution across Europe coincided with the onset of vegetation change and the arrival of trees in Western Europe. The migrational lag in vegetation response to climate change indicates that mammoths responded to the vegetation driver, and not climate change per se. The final extinction of mammoths occurred at the end of the last ice age, as mammoths were driven into isolated refugial populations in Siberia. It is thought that these small populations were then placed under pressure from human hunting activity.

In addition to the major advances in mapping the range of species, there have also been significant advances in establishing the genetic transformation of species through the Quaternary. Willerslev played an important role in the ‘molecular revolution’ and the use of ancient DNA to reconstruct species diversity, diet, and physical characteristics during the Quaternary.

 

What are the major challenges?

Following the major advances that have been made over the last few decades, a series of key questions remain:

  • We know that interglacial phases were highly variable through the Quaternary; what were the implications of this for species dynamics?
  • Where were refugia located during the cold stages of the Pleistocene?
  • How did they impact on which plants survived and/or migrated during the intervening interglacials?

 

How can palaeoecology be applied to present and future biodiversity issues?

Many ecological studies do not use palaeocological evidence to reconstruct species dynamics beyond timescales of around 50 years. At present, the fields of conservation and palaeocology are essentially disconnected. This is due to the misconception that palaeoecology is spatially and taxonomically imprecise (due to its reliance on the fragmentary fossil record); and that long-term dynamics are irrelevant for present and future conservation issues.

 

Developments in palaeoecology over the last 50 years, in terms of precision and multi-proxy approaches, means that we now have more reliable records of long-term biodiversity change. The importance of palaeoecology for establishing ‘natural’ baseline conditions (i.e. prior to human influences) is now being recognised. Without palaeoecology, we do not know what the baseline is.