Abstract:
During the Quaternary, in particular during
glacial times, different grassland ecosystems played a
much larger role and had a significantly larger distribution.
Little is known yet about past development, biodiversity
and dynamics of grassland ecosystems. In this innovative
study, we attempt to distinguish between different South
American grassland types in space and time based on
morphological pollen grain characteristics of Poaceae. For
this purpose[60?80 Poaceae pollen grains of 20 grassland
samples were measured using their length, width and pore
diameter as well as annulus width. Samples were taken
from five sites in wet Pa´ramo vegetation from the Late
Pleistocene to the Late Holocene in South Ecuador and
from two sites in the south-eastern Brazilian highlands
(Campos do Altitude) of the same period. Additionally, we
investigated two samples from a Pampa site as well as six
samples from one Campos grassland site in southern Brazil
from the Late Pleistocene to the Late Holocene. Subsets of
samples of the Campos grasslands and of the Pa´ramo were
investigated in order to retrieve more detailed information
on patterns within these vegetation types. Multivariate data
analysis of the complete data set shows changes in taxonomic
composition along an elevational gradient in the
Pa´ramo grasslands. Our results reveal a highly dynamic
development of the individual grassland types; they also
provide interesting information on Poaceae taxa composition
patterns, development and possibly changes in
biodiversity within these ecosystems. Moreover, our data
provide an indication about the origin and dynamics of the
Campos ecosystems in the southern Brazilian highlands
during the Late Pleistocene and the Holocene before and
after the onset of human activities.
