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| Titel |
Integrating the EMPD with an Alpine altitudinal training set to reconstruct climate variables in Holocene pollen records from high-altitude peat bogs |
| VerfasserIn |
Giulia Furlanetto, Federica Badino, Michele Brunetti, Elena Champvillair, Mattia De Amicis, Valter Maggi, Roberta Pini, Cesare Ravazzi, Francesca Vallé |
| 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 |
250131388
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| Publikation (Nr.) |
 EGU/EGU2016-11793.pdf |
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| Zusammenfassung |
| Temperatures and precipitation are the main environmental factors influencing vegetation and
pollen production. Knowing the modern climate optima and tolerances of those plants
represented in fossil assemblages and assuming that the relationships between plants and
climate in the past are not dissimilar from the modern ones, fossil pollen records offer
many descriptors to reconstruct past climate variables. The aim of our work is to
investigate the potential of high-altitude pollen records from an Alpine peat bog
(TBValter, close to the Ruitor Glacier, Western Italian Alps) for quantitative paleoclimate
estimates. The idea behind is that high-altitude ecosystems are more sensitive to
climate changes, especially to changes in July temperatures that severely affect the
timberline ecotone. Meantime, we met with difficulties when considering the factors
involved in pollen dispersal over a complex altitudinal mountain pattern, such as the
Alps.
We used the EMPD-European Modern Pollen Database (Davis et al., 2013) as modern
training set to be compared with our high-altitude fossil site. The EMPD dataset is
valuable in that it provides a large geographic coverage of main ecological and climate
gradients (at sub-continental scale) but lacks in sampling of altitudinal gradients and
high-altitude sites in the Alps. We therefore designed an independent altitudinal training
set for the alpine valley hosting our fossil site. 27 sampling plots were selected
along a 1700m-elevational transect. In a first step, each plot was provided with (i) 3
moss polsters collected following the guidelines provided by Cañellas-Boltà et al.
(2009) and analyzed separately to account for differences in pollen deposition at
small scale, (ii) morphometrical parameters obtained through a high-resolution
DEM, and (iii) temperature and precipitation were estimated by means of weighted
linear regression of the meteorological variable versus elevation, locally evaluated
for each site (Brunetti et al., 2014), starting from a dense and quality-controlled
observational dataset. In the most advanced step, we designed calibration functions using
modern pollen and climate data stored in the EMPD and integrated with the 27
samples from the altitudinal training set. Regression and calibration method (LWWA)
and MAT (Modern Analogue Technique) were used to reconstruct temperatures
and precipitation. We applied the models to our fossil site to infer temperatures of
the coldest (Tjan) and warmest (Tjul) months and the mean annual precipitation
(Pann). Finally we compared our results with established climate proxy records
(oxygen isotope records from ice cores, records of Alpine Glaciers fluctuations,
stalagmites).
This research is promoted by the CNR-DTA NextData Project.
Brunetti et al., 2014. International Journal of Climatology 34, 1278-1296.
Cañellas-Boltà et al., 2009. The Holocene 19(8), 1185-1200.
Davis et al., 2013. Vegetation History and Archaeobotany 22, 521-530. |
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