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Chironomids, temperature and numerical models: a reply to SeppäläDepartment of Ecology and Systematics, Division of Hydrobiology, University of Helsinki, PO Box 17 (Arkadiankatu 7), FIN-00014 Helsinki, Finland
Botanical Institute, University of Bergen, Allégaten 41, N-5007 Bergen, Norway, and Environmental Change Research Centre, University College London, 26 Bedford Way, London WC1H 0AP, UK
Geological Survey of Finland, PO Box 96, FIN-02151 Espoo, Finland
Department of Geography, PO Box 64, FIN-00014 University of Helsinki, Finland We reply to comments by Seppälä (2001) concerning the suitability of the surface-water temperature measurements and mean July air temperature estimates used by Olanderet al. (1999) to derive quantitative chironomid-temperature transfer functions. We use new data for water temperatures based on two-hourly recordings from thermistors installed in 32 lakes and air-temperature data from an automatic weather station at one lake to refute Seppäläs accusations that our field data are unsatisfactory. We also respond to Seppäläs suggestions about factors influencing chironomid distribution and abundance and suggest that there is a serious confusion of temporal and spatial scales between Seppäläs ideas and the Olanderet al. study. We attempt to explain the underlying logic behind empirical transfer functions that form a major part of Holocene quantitative environmental reconstructions and the major assumptions behind such transfer functions as Seppälä appears not to understand the basis or the assumptions of such widely used numerical models in palaeolimnology. We respond to Seppäläs comments that lakewater pH and distance beyond tree-line have been inadequately measured and answer his erroneous understanding that a helicopter was used to facilitate lake sampling. We briefly consider Seppäläs suggestion that a helicopter can totally mix the surface water of a lake for many hours.
Key Words: Chironomidae calibration modelling transfer functions summer temperature palaeotemperatures field measurements northern Fennoscandia
The Holocene, Vol. 11, No. 5,
615-622 (2001) This article has been cited by other articles:
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