| Title | Modern diatom, cladocera, chironomid, and chrysophyte cyst assemblages as quantitative indicators for the reconstruction of past environmental conditions in the Alps .1. Climate |
| Abstract | Diatom, chrysophyte cyst, benthic cladocera, planktonic cladocera, and chironomid assemblages were studied in the surface sediments of 68 small lakes along an altitudinal gradient from 300 to 2350 m in Switzerland. In addition, 43 environmental variables relating to the physical limnology, geography, catchment characteristics, climate, and water chemistry were recorded or measured for each lake. The explanatory power of each of these predictor variables for the different biological data-sets was estimated by a series of canonical correspondence analyses (CCA) and the statistical significance of each model was assessed by Monte Carlo permutation tests. A minimal set of environmental variables was found for each biological data-set by a forward-selection procedure within CCA. The unique, independent explanatory power of each set of environmental variables was estimated by a series of CCAs and partial CCAs. Inference models or transfer functions for mean summer (June, July, August) air temperature were developed for each biological data-set using weighted-averaging partial least squares or partial least squares. The final transfer functions, after data screening, have root mean squared errors of prediction, as assessed by leave-one-out cross-validation, of 1.37 degrees C (chironomids), 1.60 degrees C (benthic cladocera), 1.62 degrees C (diatoms), 1.77 degrees C (planktonic cladocera), and 2.23 degrees C (chrysophyte cysts). |
| Source | Journal of paleolimnology 18 (4), pp. 395–420 |
| Keywords | transfer functionsweighted-averaging partial-least-squaressummer temperaturessurface sedimentsmodern training-setsSwitzerland |
| Journal | Journal of paleolimnology |
| Editor | Kluwer Academic, Boston, Paesi Bassi |
| Year | 1997 |
| Type | Articolo in rivista |
| DOI | 10.1023/A:1007982008956 |
| Authors | Lotter, AF; Birks, HJB; Hofmann, W; Marchetto, A |
| Text | 481092 1997 10.1023/A 1007982008956 ISI Web of Science WOS 000071606800005 transfer functions weighted averaging partial least squares summer temperatures surface sediments modern training sets Switzerland Modern diatom, cladocera, chironomid, and chrysophyte cyst assemblages as quantitative indicators for the reconstruction of past environmental conditions in the Alps .1. Climate Lotter, AF; Birks, HJB; Hofmann, W; Marchetto, A Univ Bern; Swiss Fed Inst Environm Sci Technol; Univ Bergen; UCL; Max Planck Inst Limnol; CNR Diatom, chrysophyte cyst, benthic cladocera, planktonic cladocera, and chironomid assemblages were studied in the surface sediments of 68 small lakes along an altitudinal gradient from 300 to 2350 m in Switzerland. In addition, 43 environmental variables relating to the physical limnology, geography, catchment characteristics, climate, and water chemistry were recorded or measured for each lake. The explanatory power of each of these predictor variables for the different biological data sets was estimated by a series of canonical correspondence analyses CCA and the statistical significance of each model was assessed by Monte Carlo permutation tests. A minimal set of environmental variables was found for each biological data set by a forward selection procedure within CCA. The unique, independent explanatory power of each set of environmental variables was estimated by a series of CCAs and partial CCAs. Inference models or transfer functions for mean summer June, July, August air temperature were developed for each biological data set using weighted averaging partial least squares or partial least squares. The final transfer functions, after data screening, have root mean squared errors of prediction, as assessed by leave one out cross validation, of 1.37 degrees C chironomids , 1.60 degrees C benthic cladocera , 1.62 degrees C diatoms , 1.77 degrees C planktonic cladocera , and 2.23 degrees C chrysophyte cysts . 18 Published version Articolo in rivista Kluwer Academic 0921 2728 Journal of paleolimnology Journal of paleolimnology J. paleolimnol. aldo.marchetto MARCHETTO ALDO |
