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Titel |
Longer growing seasons and warm summers boost Rhododendron ferrugineum L. growth in the Taillefer massif (French Alps) |
VerfasserIn |
Loïc Francon, Christophe Corona, Erwan Roussel, Jérôme Lopez Saez, Markus Stoffel |
Konferenz |
EGU General Assembly 2017
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Medientyp |
Artikel
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Sprache |
en
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Digitales Dokument |
PDF |
Erschienen |
In: GRA - Volume 19 (2017) |
Datensatznummer |
250137719
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Publikation (Nr.) |
EGU/EGU2017-523.pdf |
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Zusammenfassung |
Rhododendron ferrugineum L. is an important and widespread dwarf shrub species
growing in high-elevation, alpine environments of the Western European Alps. As
such, it is likely to offer unique opportunities which would allow pushing current
dendrochronological networks into extreme environments and way beyond the
upper survival limit of trees. Given that different species of the same genus have
been successfully used in tree-ring investigations, notably in the Himalayas where
Rhododendron sp. has proven to be a reliable climate proxy, this study aims at (i) evaluating
the dendroclimatological potential of the widely distributed R. ferrugineum and
at (ii) determining the major limiting climate factor driving species growth and
the formation of rings. To this end, 154 cross-sections from 36 R. ferrugineum
individuals have been sampled above local treelines and at elevations comprised
between 1800 and 2100 m asl on NW-facing slopes of the Taillefer massif (French
Alps). We illustrate a 195-year-long standard chronology based on growth-ring
records selected from 24 individuals, and document that the series is well-replicated
for almost one century (1920-2015) with an Expressed Population Signal (EPS)
>0.85. Analysis using partial and seasonal correlation functions further highlight that
growth of Rhododendron is governed by temperatures during the growing season
(May-July), with increasingly higher air temperatures favoring larger ring widths, a
phenomenon which is well known from dwarf shrubs growing in circum-arctic tundra
ecosystems. Similarly, the negative effect of January-February precipitation on radial
growth of R. ferrugineum, rarely observed in the Arctic, is interpreted as a result of
reduced growing seasons following snowy winters. We conclude that the strong and
unequivocal signals recorded in the fairly long R. ferrugineum chronologies presented here
can indeed be used for climate–growth studies as well as for the reconstruction of
climatic fluctuations in Alpine regions beyond the upper limits of present-day forests. |
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