The separation of the influence of nutrients and climate on the varve time-series of baldeggersee, Switzerland |
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| Authors: | A F Lotter H J B Birks |
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| Institution: | (1) Geobotanical Institute, University of Bern, Altenbergrain 21, CH-3013 Bern, Switzerland;(2) Swiss Federal Institute for Environmental Science and Technology (EAWAG), CH-8600 Dübendorf, Switzerland;(3) Botanical Institute, University of Bergen, Allégaten 41, N-5007 Bergen, Norway;(4) Environmental Change Research Centre, Dept. of Geography, University College London, 26 Bedford Way, WC1H 0AP London, UK |
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| Abstract: | The varve data-set from a freeze-core taken in the deepest part of Baldeggersee was subjected to different multivariate statistical
analyses in order to estimate the amount of variance in the varve thickness measures explicable by past climate and by the
trophic state of the lake. A comparison of two different time-periods (1902 to1992 versus 1920 to 1980) revealed that the
lake restoration programme since 1982 has had a significant impact on the formation of the seasonal layers. Results of the
partitioning of the variance in the varve thickness measures showed that about two thirds of the variance are unexplained
by a climate and trophic state model and that trophic state explains 6%, whereas climate accounts for about 28% of the variance
before the effect of lake restoration had a strong impact on the varves. Among the climate parameters the amount of annual
precipitation is a strong predictor for explaining the thickness of both dark layer and total couplet thickness, whereas summer
precipitation is important for the thickness of the light layer. |
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| Keywords: | Variance partitioning redundancy analysis multiple linear regression eutrophication varves |
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