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| Titel |
Multicentury Reconstruction of Precipitations (1300-2014) in Eastern Canada
from Tree-Ring Width and Carbon and Oxygen Isotopes |
| VerfasserIn |
Claudie Giguère, Etienne Boucher, Yves Bergeron |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250125552
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| Publikation (Nr.) |
 EGU/EGU2016-5141.pdf |
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| Zusammenfassung |
| Tree ring series enabling long hydroclimatic reconstructions are scarce in Northeastern
America, mostly because most boreal species are rather thermo-dependant. Here we
propose a new multi-proxy analysis (tree-ring, δ13C and δ18O) from one of the oldest
Thuja occidentalis population in NE America (lake Duparquet, Quebec). These rare
precipitation-sensitive, long-living trees (> 800 years) grow on xeric rocky shores and their
potential for paleo-hydroclimatic reconstructions (based on ring widths solely) was
previously assessed. The objectives of this study are twofold i) to strengthen the
hydroclimatic signal of this long tree-ring chronology by adding analysis of stable
isotope ratios (δ13C and δ18O) and ii) to reconstruct summer precipitation back to
1300 AD, which will represent, by far, the longest high-resolution hydroclimatic
reconstruction in this region. A tree-ring chronology was constructed from 61 trees
sampled in standing position. Eleven trees were also sampled to produce pooled
carbon and oxygen isotope chronologies (annually resolved) with a replication of
five to six trees per year. Signal analysis (correlation between climatic data and
proxy values) confirms that growth is positively influenced by spring precipitations
(May-June), while δ13C is negatively correlated to summer precipitation (June to
August) and positively to June temperature. Adding δ18O analysis will strengthen
the signal even more, since wood cellulose should be enriched in δ18O when high
evapotranspiration conditions prevail. Based on a multi-proxy approach, a summer
precipitation reconstruction was developed and compared to other temperature
reconstructions from this region as well as to southernmost hydroclimatic reconstructions
(e.g. Cook et al). A preliminary analysis of external and internal forcing is proposed in
conclusion. |
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