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Intralake training set of fossil Cladocera for paleohydrological inferences: evidence for multicentennial drought during the Medieval Climate Anomaly

Authors


L. Nevalainen, Environmental Protection and Research, City of Helsinki Environment Centre, P.O. Box 500, FI-00099 Helsinki, Finland.

E-mail: liisa.nevalainen@helsinki.fi

ABSTRACT

We investigated an intralake surface sediment data set for fossil Cladocera from Lake Pieni-Kauro, eastern Finland, with an objective to develop a paleohydrological inference model for lake level reconstructions. The Cladocera assemblages showed high heterogeneity among the sampling sites according to the water depth gradient, thus enabling the construction of a quantitative inference model for water level reconstructions. The strongest model was developed using weighted averaging with classical deshrinking regression. This model had a jackknifed coefficient of determination of 0.79 and a root mean squared error of prediction of 0.79 m. We tested the performance of the model on previously available Cladocera stratigraphy and Cladocera-based and chironomid-based lake level reconstructions from Lake Iso Lehmälampi, southern Finland. The lake level reconstructions, based on different proxies and independent inference models, showed high levels of similarity, indicating a period of lower water table during the Medieval Climate Anomaly around 1000  ad. The results suggest that the applicability of intralake paleohydrological models may not be regionally restricted when applied to similar lake types and, therefore, provide an alternative perspective on paleolimnological training set design and paleoclimatological inferences. Copyright © 2011 John Wiley & Sons, Ltd.

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