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| Titel |
North Patagonia climate over the last millennium inferred from variations in tree-ring width and isotopic composition |
| VerfasserIn |
Aliénor Lavergne, Ricardo Villalba, Valérie Daux |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250086401
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| Publikation (Nr.) |
 EGU/EGU2014-258.pdf |
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| Zusammenfassung |
| To disentangle natural variability from man-induced climate changes, current climatic
trends should be placed in a longer perspective. Tree-rings provide a wealth of
information on past climates with high-resolution records covering up to thousands years.
Recent tree-ring studies have highlighted the divergence phenomenon in Northern
Hemisphere forests. At some temperature-limited northern sites, tree growth responses to
climate during recent decades have changed, raising concerns about the quality
of historical climate reconstructions based on tree-ring widths. This shift in the
eco-physiological response of trees to climate has not yet been documented in the
Southern Hemisphere. The aim of this study is to present the tree-ring evolution over
the last centuries in northern Patagonia (southern South America; 41°10’S-71Ë
50’W) in order to assess 1) divergence in tree-growth response to climate in recent
decades, and 2) the potential of tree-ring parameters (width and δ18O) to reconstruct
temperature and atmospheric circulation patterns such as the Southern Annular Mode
(SAM).
Based on quality and extent, instrumental temperature records across North Patagonia
(39°-41°S) were selected for comparison with tree-ring records. Detection and correction of
series inhomogeneities were conducted using HOMER software. A set of homogenized
temperature data was developed for the period 1901-2013. Increment-borer samples from
Fitzroya cupressoides and Nothofagus pumilio were collected along the regional precipitation
gradient from the wet Valdivian rainforest to the mesic Patagonian forests during the austral
summer of 2013. Six sampling sites (2 for Fitzroya, 4 for Nothofagus) along the gradient
were established to maximize differences in tree-growth responses to climate and
to assess the effect of precipitation on the responses. More than 500 cores were
cross-dated, detrended and indexed. Composite tree-ring index (TRI) chronologies of
F. cupressoides and N. pumilio extending from the late 9thcentury to 2011 were
developed. Variations in ring widths were compared between species and sites and
correlated with climate parameters. The two Fitzroya chronologies show a long-term
period of common variations in tree growth (r = 0.7-0.9, p |
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