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 establisment and mortality in Patagonia.
Autor/es:
AMOROSO, M.; SUAREZ, M. L.; SRUR A. M.; MORALES M.; VILLALBA R.
Lugar:
Valdivia
Reunión:
Simposio; II International Symposium "Reconstructing Climate Variations in South America and the Antarctic Peninsula over the last 2000 years".; 2010
Institución organizadora:
Centro de Ingenieria de la InnovaciĆ³n y Facultad de Ciencias Forestales y Recursos Naturales
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 deficit 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.
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