J Paleolimnol (2006) 36:295-314 DOl 1O.1007/s10933-006-0014-6 A northwest North American training set: distribution of freshwater midges in relation to air temperature and lake depth Erin M. Barley' Ian R. Walker' Joshua Kurek, Les C. Cwynar' Rolf W. Mathewes • Konrad Gajewski' Bruce P. Finney Received: 20 July 2005 I Accepted: 5 March 2006/Published online: 26 August 2006 © Springer Science+Business Media B.Y. 2006 Abstract Freshwater midges, consisting of Chiro- organic carbon, lichen woodland vegetation and sur- nomidae, Chaoboridae and Ceratopogonidae, were face area contributed significantly to explaining assessed as a biological proxy for palaeoclimate in midge distribution. Weighted averaging partial least eastern Beringia. The northwest North American squares (WA-PLS) was used to develop midge training set consists of midge assemblages and data inference models for mean July air temperature 2 for 17 environmental variables collected from 145 (R boot = 0.818, RMSEP = 1.46°C), and transformed 2 lakes in Alaska, British Columbia, Yukon, Northwest depth (1n (x+ l); R boot = 0.38, and RMSEP = 0.58). Territories, and the Canadian Arctic Islands. Canon- ical correspondence analyses (CCA) revealed that Key words Chironomidae : Transfer function . mean July air temperature, lake depth, arctic tundra Beringia' Air temperature . Lake depth' Canonical vegetation, alpine tundra vegetation, pH, dissolved correspondence analysis . Paleoclimate E. M. Barley· R. W. Mathewes Department of Biological Sciences, Simon Fraser University, Burnaby, British Columbia, Canada V5A IS6 Introduction I. R. Walker Departments of Biology, and Earth and Environmental Sciences, University of British Columbia Okanagan, Palaeoecologists seeking to quantify past environ- Kelowna, BC, Canada VIV IV7 mental changes rely increasingly on transfer func- e-mail:
[email protected] tions that make use of biological proxies (Battarbee J.