IANIGLA   20881
INSTITUTO ARGENTINO DE NIVOLOGIA, GLACIOLOGIA Y CIENCIAS AMBIENTALES
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Influences of past climate variations on tree establishment and mortality in Patagonia
Autor/es:
AMOROSO, M; SUAREZ, M.L; SRUR, A; MORALES, M; VILLALBA, R
Lugar:
Valdivia
Reunión:
Conferencia; II International Symposium Reconstructing Climate Variations in South America and the Antartic Peninsula over the last 2000 years; 2010
Institución organizadora:
PAGES Past Global changes
Resumen:
Instrumental and proxy records indicate that some regions in
Patagonia are
likely experiencing the warmest interval of the past millennium.
Concurrent
with warmer conditions, precipitation has experience a reduction
during the
past decades. Present climatic conditions could be affecting the
structure of
the Patagonian forests through direct effects on tree
demography. We evaluated
the effect of climate variations on the establishment and
mortality of tree
species along the Argentinean Patagonian Andes using
dendrochronological
techniques. The dynamics of Austrocedrus chilensis in the
forest-steppe ecotone
responds to dry-wet climatic events. Decades with a predominance
of
cool-wet summers favor the establishment of the Austrocedrus
while mortality
events are associated with extreme drought events during one or
two
consecutive dry-warm summers. Similarly, periodic mortality in
mesic and
dense A. chilensis forests is related to particularly dry and warm climatic
conditions
in northern Patagonia. For the Nothofagus dombeyi populations at
the
eastern sector of its distribution range, tree mortality follows
droughts. After
mortality, resources released by dead trees concurrent with wet
periods favor
tree establishment, showing the dependence of successful tree
recruitment
on favorable wet periods for growth and survival of seedlings.
Based on the
negative impact of recent extreme droughts on N. dombeyi populations at its
eastern range, changes in this species distribution as a
consequence of future
climate change are expected. The recent increase in temperatures
in southern
Patagonia, in combination with extended growing seasons, has
facilitated the
establishment of individuals of Nothofagus pumilio above the
present upper
treeline. Moreover, an increase in tree mortality rates has been
recorded during
the past three decades at the lower-elevation stands of this
species. The
increase in water deicit during the last decades has lead to
abundant tree
mortality from the forest-steppe ecotones to mid-elevation
forests, whereas
warmer summers have facilitated the forest expansion at the
upper, relatively-
humid treelines