An expanded surface-water palaeotemperature inference model for use with fossil midges from eastern Canada
Tóm tắt
Using an expanded surface sample data set, representing lakes distributed across a transect from southernmost Canada to the Canadian High Arctic, a revised midge-palaeotemperature inference model was developed for eastern Canada. Modelling trials with weighted averaging (with classical and inverse deshrinking; with and without tolerance downweighting) and weighted averaging partial least squares (WA-PLS) regression, with and without square-root transformation of the species data, were used to identify the best model. Comparison of measured and predicted temperatures revealed that a 2 component WA-PLS model for square-root transformed percentage species data provided the model with the highest explained variance (r
$$_{jack}^2 $$
= 0.88) and the lowest error estimate (RMSEP
jack
= 2.26 °C). Comparison of temperature inferences based on the new and old models indicates that the original model may have seriously under-estimated the magnitude of late-glacial temperature oscillations in Atlantic Canada. The new inferences suggest that summer surface water temperatures in Splan Pond, New Brunswick were approximately 10 to 12 °C immediately following deglaciation and during the Younger Dryas. During the Allerod and early Holocene, surface water temperatures of 20 to 24 °C were attained. The new model thus provides the basis for more accurate palaeotemperature reconstructions throughout easternmost Canada.
Tài liệu tham khảo
Birks, H. J. B., 1995. Quantitative palaeoenvironmental reconstructions. In D. Maddy & J. S. Brew (ed.), Statistical Modelling of Quaternary Science Data. Technical Guide 5, Quaternary Research Assoc., Cambridge: 161–254.
Birks, H. J. B., J. M. Line, S. Juggins, A. C. Stevenson & C. J. F. ter Braak, 1990. Diatoms and pH reconstruction. Phil. Trans. r. Soc. Lond. B 327: 263–278.
Bliss, L. C. (ed.), 1977. Truelove Lowland, Devon Island, Canada: A High Arctic Ecosystem. University of Alberta Press, Edmonton, 714 pp.
Cwynar, L. C. & A. J. Levesque, 1995. Chironomid evidence for late-glacial climatic reversals in Maine. Quat. Res. 43: 405–413.
Fritz, S. C., S. Juggins, R. W. Battarbee & D. R. Engstrom, 1991. Reconstruction of past changes in salinity and climate using a diatom-based transfer function. Nature 352: 706–708.
Hill, M. O., 1973. Diversity and evenness: a unifying notation and its consequences. Ecology 54: 427–432.
Levesque, A. J., 1995. Late-glacial climate and vegetation change in Atlantic Canada. Ph. D. thesis, University of New Brunswick, Fredericton, 167 pp.
Levesque, A. J., F. E. Mayle, I. R. Walker & L. C. Cwynar, 1993a. A previously unrecognized late-glacial cold event in eastern North America. Nature 361: 623–626.
Levesque, A. J., F. E. Mayle, I. R. Walker & L. C. Cwynar, 1993b. The Amphi-Atlantic Oscillation: a proposed late-glacial climatic event. Quat. Sci. Rev. 12: 629–643.
Levesque, A. J., L. C. Cwynar & I. R. Walker, 1994. A multi-proxy investigation of late-glacial climate and vegetation change at Pine Ridge Pond, southwest New Brunswick, Canada. Quat. Res. 42: 316–327.
Levesque, A. J., L. C. Cwynar & I. R. Walker, 1996. Richness, diversity and succession of late-glacial chironomid assemblages in New Brunswick, Canada. J. Paleolimnol. 16: 257–274.
Levesque, A. J., L. C. Cwynar & I. R. Walker, in press. Exceptionally strong north-south gradients in lake temperatures during the last deglaciation. Nature.
Lindegaard, C. & K. P. Brodersen, 1995. Distribution of Chironomidae (Diptera) in the river continuum. In P. Cranston (ed.), Chironomids: From Genes to Ecosystems. CSIRO Publications, Melbourne: 257–271.
Line, J. M., C. J. F. ter Braak & H. J. B. Birks, 1994. WACALIB version 3.3 — a computer program to reconstruct environmental variables from fossil assemblages by weighted averaging and to derive sample-specific errors of prediction. J. Paleolimnol. 10: 147–152.
Oliver, D. R. & M. E. Roussel, 1983. The insects and arachnids of Canada. Part 11: The genera of larval midges of Canada; Diptera: Chironomidae. Agric. Can. Publ. 1746: 1–263.
Prentice, I. C., 1980. Multidimensional scaling as a research tool in Quaternary palynology: a review of theory and methods. Rev. Paleobot. Palynol. 31: 71–104.
Rossaro, B., 1992. Chironomids and water temperature. Aquatic Insects 13: 87–98.
Sæther, O. A., 1977. Female genitalia in Chironomidae and other Nematocera: morphology, phylogenies, keys. Bull. Fish. Res. Bd Can. 197: 1–209.
ter Braak, C. J. F., 1987. Calibration. In R. H. G. Jongman, C. J. F. ter Braak & O. F. R. van Tongeren (ed.), Data analysis in community and landscape ecology. Centre for Agricultural Publishing and Documentation (Pudoc), Wageningen, The Netherlands: 78–90.
ter Braak, C. J. F., 1987–1992. CANOCO — a FORTRAN program for canonical community ordination. Microcomputer Power, Ithaca, N.Y., 95 pp.
ter Braak, C. J. F. & S. Juggins, 1993. Weighted averaging partial least squares regression (WA-PLS): an improved method for reconstructing environmental variables from species assemblages. Hydrobiologia 269/270: 485–502.
ter Braak, C. J. F., S. Juggins, H. J. B. Birks & H. van der Voet, 1993. Weighted avaraging partial least squares regression (WAPLS-: definition and comparison with other methods for species-environment calibration. In: G. P. Patil & C. R. Rao (ed.), Multivariate Environmental Statistics. Elsevier Science Publishers, Amsterdam: 525–560.
Walker, I. R., 1988. Late-Quaternary Palaeoecology of Chironomidae (Diptera: Insecta) from Lake Sediments in British Columbia. Ph. D. thesis, Simon Fraser University, Burnaby, British Columbia, Canada, 204 pp.
Walker, I. R. & R. W. Mathewes, 1989. Chironomidae (Diptera) remains in surficial lake sediments from the Canadian Cordillera: analysis of the fauna across an altitudinal gradient. J. Paleolimnol. 2: 61–80.
Walker, I. R., J. P. Smol, D. R. Engstrom & H. J. B. Birks, 1991a. An assessment of Chironomidae as quantitative indicators of past climatic change. Can. J. Fish. aquat. Sci. 48: 975–987.
Walker, I. R., R. J. Mott & J. P. Smol, 1991b. Allerød — Younger Dryas lake temperatures from midge fossils in Atlantic Canada. Science 253: 1010–1012.
Walker, I. R., S. E. Wilson & J. P. Smol, 1995. Chironomidae (Diptera): Quantitative palaeosalinity indicators for lakes of western Canada. Can. J. Fish. aquat. Sci. 52: 950–960.
Wiederholm, T. (ed.), 1983. Chironomidae of the Holarctic Region, Keys and diagnoses: Part 1 — Larvae. Entomologica scandinavica Supplement 19: 1–457.
Wilson, S. E., I. R. Walker, R. J. Mott & J. P. Smol, 1993. Climatic and limnological changes associated with the Younger Dryas in Atlantic Canada. Climate Dynamics 8: 177–187.