The full programme book (PDF) - Royal Geographical Society

THEME 9: PALAEOECOLOGY
The contribution of vegetation palaeoecology: from molecules to maps
Mary E. Edwards
Geography and Environment, University of Southampton, Highfield, Southampton
SO17 1BJ
Plant palaeoecological data are extraordinarily versatile, lending themselves to fine-scale,
detailed reconstructions of changing local landscapes, on the one hand, and the mapping
of global shifts in biome distributions on the other-and much else at scales in-between.
The limits to the spatial, temporal and taxonomic resolution of palaeodata have been
known to frustrate “neo” ecologists, yet the insights into ecological and biogeographical
processes that have been achieved are impressive. Concern over climate change has
brought the dramatic records found in palaeodata firmly into the mainstreams of ecology,
conservation biology and climate change science. The mapping of pollen data to show
biogeographic patterns extends back to the early years of palaeoecology and has
provided insights into a range of questions in ecology and biogeography, particularly as
the amount of data available has increased. The expansion patterns of northern tree
species recolonizing post-glacial landscapes highlighted the importance of long-distance
migration as a response to climate change. Mapping demonstrated the individualistic
nature of species migration and the ephemeral nature of plant community composition.
Recently, comparison of migration routes with contemporary genetic information has
contributed to the assessment of the evolutionary consequences of range changes, and
the identification of refugial (or relictual) populations raises questions as to the importance
of refugial populations as centres of expansion.
At smaller scales palaeoecology addresses the reconstruction of landscape-scale
community structure and composition. Palaeoecologists have long sought-and only
recently found-an effective way to compensate for the bias in pollen representation that
confounds attempts to describe, for example, proportions of open and forested land within
a landscape, or to provide land-cover maps that reflect patterns of past human influence
on landscapes. Plant macrofossils complement pollen data, providing unequivocal
evidence of plant presence and greatly enhancing the floristic information detail of past
plant assemblages. Now, biomolecules offer a complementary approach: the technical
revolution in molecular biology has made possible the extraction of a range of molecules
from Quaternary sediments that can indicate the presence of organisms from Archaea to
Artemisia. Molecular records furthermore provide insight into some key biogeochemical
processes. As with macrofossils, the molecular information is, typically, local and
taxonomically specific. There is great potential here for novel science-but as these data,
like almost all Quaternary data, derive from sediments, there is much work ahead to
establish exactly what they mean.
Keywords: pollen data; mapping; refugia; migration; landscape reconstruction; ancient
biomolecules.