INVESTIGADORES
SUAREZ Maria Laura
congresos y reuniones científicas
Título:
Climate-induced widespread dieback of dominant tree species may lead to rapid large-scale vegetation shifts
Autor/es:
KITZBERGER, THOMAS; SUAREZ, MARIA LAURA
Lugar:
San Jose, California. USA
Reunión:
Congreso; ESA/SER Joint Meeting: Ecological Restoration in a Changing World; 2007
Institución organizadora:
Ecological Society of America & Society for Ecological Restoration International
Resumen:
We analyzed mechanisms of
potential forest composition shift related to a mass mortality event triggered
by an ENSO-related warm drought occurred in 1998-99 in mixed Nothofagus-Austrocedrus
forests of northern Patagonia. Extensive sampling of these transitional
forests showed that mortality of adult trees during the 1998-99 drought was an
order of magnitude higher in the angiosperm Nothofagus dombeyi (11-57%
of trees killed) than in the conifer Austrocedrus chilensis (0-5% of
trees killed). Composition of the forest changed from being N. dombeyi-dominated
(65%) to a nearly equally represented mixed N. dombeyi-A. chilensis forest.
Likewise, 7-30% of N. dombeyi saplings were killed compared to 1-1.2% of
A. chilensis saplings. N. dombeyi reduced its density of live
trees from 243 to 105 trees ha-1 resulting
in numerous drought-gaps. Drought gaps had lower diffuse radiation levels and
100% lower summer soil moisture contents compared to nearby tree fall gaps. Two-year
monitoring natural seedling establishment within drought gaps indicates that A.
chilensis seedlings survived 4 times more than N. dombeyi seedlings.
Likewise, 2-year survival of transplanted seedlings was 3 times higher in
conifer vs. angiosperm seedlings. Five years after the event, A. chilensis seedlings
established in drought gaps were 5 times more abundant than N. dombeyi seedlings,
contrasting with similar densities under undisturbed canopies. Our results
document important angiosperm-to-conifer shifts mediated by drought and suggest
that dieback-induced compositional shifts of forests may not only be driven by
differential adult and sapling mortality but also by post-drought biotic and
abiotic changes affecting tree seedling recruitment performance.