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| Titel |
Dendrochronology and lakes: using tree-rings of alder to reconstruct lake levels |
| VerfasserIn |
Ernst van der Maaten, Allan Buras, Tobias Scharnweber, Sonia Simard, Knut Kaiser, Sebastian Lorenz, Marieke van der Maaten-Theunissen, Martin Wilmking |
| 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 |
250088445
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| Publikation (Nr.) |
 EGU/EGU2014-2549.pdf |
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| Zusammenfassung |
| Climate change is considered a major threat for ecosystems around the world. Assessing its
effects is challenging, amongst others, as we are unsure how ecosystems may respond to
climate conditions they were not exposed to before. However, increased insight may be
obtained by analyzing responses of ecosystems to past climate variability. In this respect, lake
ecosystems appear as valuable sentinels, because they provide direct and indirect
indicators of change through effects of climate. Lake-level fluctuations of closed
catchments, for example, reflect a dynamic water balance, provide detailed insight in past
moisture variations, and thereby allow for assessments of effects of anticipated climate
change.
Up to now, lake-level data are mostly obtained from gauging records and reconstructions
from sediments and landforms. However, these records are in many cases only available over
relatively short time periods, and, since geoscientific work is highly demanding,
lake-level reconstructions are lacking for many regions. Here, we present and discuss an
alternative method to reconstruct lake levels, which is based on tree-ring data of black
alder (Alnus glutinosa L.). This tree species tolerates permanently waterlogged and
temporally flooded conditions (i.e. riparian vegetation), and is often found along
lakeshores. As the yearly growth of trees varies depending upon the experienced
environmental conditions, annual rings of black alder from lakeshore vegetation
likely capture information on variations in water table, and may therefore be used
to reconstruct lake levels. Although alder is a relatively short-lived tree species,
the frequent use of its’ decay-resistant wood in foundations of historical buildings
offers the possibility of extending living tree-chronologies back in time for several
centuries.
In this study, the potential to reconstruct lake-level fluctuations from tree-ring
chronologies of black alder is explored for three lake ecosystems in the Mecklenburg Lake
District, northeastern Germany. Tree-ring data were collected from black alder forests
surrounding the lakes ‘Tiefer See’, ‘Drewitzer See’ and ‘Großer Fürstenseer See’. At all
research sites, increment cores were extracted from at least 15 trees (2 cores per
tree) using an increment borer. In the tree-ring lab DendroGreif, these cores were
prepared and annual tree-ring widths were measured. Thereafter, site-specific tree-ring
chronologies were built using established detrending and standardization procedures.
Preliminary results show that the growth of alder reacts upon water level fluctuations.
We visually and statistically compare the developed tree-ring chronologies with
historical lake-level records, and retrospectively model lake levels. Findings will
be presented while critically reflecting upon the quality of these reconstructions. |
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