INVESTIGADORES
BAMONTE Florencia Paula
congresos y reuniones científicas
Título:
Vegetation and environmental changes in Extra-Andean Patagonia, Argentina
Autor/es:
MANCINI, MARÍA VIRGINIA; BAMONTE, F.P.; MARCOS, M.A.
Lugar:
Valle Uco
Reunión:
Conferencia; 4th Southern Deserts Conference; 2014
Institución organizadora:
Laboratorio de Paleo-Ecología Humana FCEN-UNCUYO
Resumen:
Extra-Andean Patagonia is a large region with
arid and semiarid climatic conditions. Mean
annual precipitation is lower than 200 mm due
to the rainshadow effect produced by the Andes.
Spatial variation of rainfall is one of the causes of
vegetation patchiness which is represented by
grass, shrub ,and dwarf-shrub steppes. Modern
pollen?vegetation?climate relationships from
different precipitation gradients were
established as analogs to understand Holocene
vegetation dynamics. According to the current
correlation between precipitation and wind
speed, changes revealed by the pollen records
are interpreted as indicative of variations in the
intensity and/or position of the westerlies; the
influence of Atlantic moist air is more
pronounced toward the east. These atmospheric
circulation changes led to drifts of the foreststeppe ecotone and in steppe composition.
Paleoenvironmental reconstructions are based
on pollen records comparison from different
depositional environments such as ?mallines,?
lakes and archaeological sites (caves and
rockshelters). Palynology of archaeological
contexts generates essential information that
properly combined and integrated can improve
the understanding of past landscapes. An
important consideration is the stratigraphic
resolution of archaeological sequences.
Comparison of fossil pollen records from
archaeological sites and those analyzed from
other deposits strengthen paleoclimatic
reconstructions, can be used to assess similarities
and differences in the distribution patterns of
vegetation and their relationship with regional
(climate) and/or local (topography, substrate,
disturbance) changes. Environmental
reconstruction presents similar trends during the
Pleistocene?Holocene transition. Human
occupation beginning in the Late Pleistocene
and early Holocene in the southern steppe
suggests that humans utilized the area during
times of increased moisture. Major human
impact on vegetation began around 150 years
ago with the European settlement; overgrazing
led to changes specially in the grass steppe. The
agreement between these trends and other
paleoenvironmental interpretations based on
pollen, charcoal, and sedimentological records
suggests that the reconstructed features reflect
large-scale climatological patterns over
Patagonia. However, stratigraphical and
chronological discontinuities, with
unrepresented processes, limit knowledge of
past environmental change. A few continuous
lacustrine records of the climatic and ecological
history are available for southernmost Patagonia.
Other paleoenvironmental reconstructions are
needed to achieve a better understanding of the
regional changes that make it possible to identify
climatic events and to contribute new insights to
the role of atmospheric circulation at these
latitudes. For these reasons, the following is
recommended for future studies: increasing high
resolution paleoecological records and analyzing
continuous sequences of the steppe to compare
with available reconstructions.