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27. Paleolimnology

Author

Davis, Margaret B., primary, Ford, M. S., additional, Moeller, Robert E., additional, Sherman, John W., additional, Goulden, Clyde, additional, Vostreys, Gay, additional, Davis, Margaret B., additional, and Ford, M S., additional

Published
1985
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31. Paleoecology of range limits: beech in the upper peninsula of Michigan

Author

Woods, Kerry D. and Davis, Margaret B.

Subjects
Michigan -- Environmental aspects, Seeds -- Dispersal, Beech -- Environmental aspects, Paleoecology -- Michigan, Biological sciences, Environmental issues
Abstract

Fossil pollen was used to map American beech (Fagus grandifolia) populations in Wisconsin and Michigan during the last 8000 yr. Among questions addressed were: (1) What were routes and rates of range expansion? (2) Did range expansion follow a 'wave-front' model or occur by coalescence of outliers? (3) Has the range of beech been determined by environmental tolerance or by dispersal rate? Presettlement distributions were mapped from survey records. Range expansion was reconstructed using pollen diagrams from 34 sites, most in a 30-50 km grid. We show beech moving through southern Michigan into Wisconsin and Michigan's Upper Peninsula. During much of the last 8000 yr the range of beech was relatively stable and presumably environmentally controlled. Brief delays may have been occasioned by dispersal barriers. Range expansions occurred during the last millennium, as well as 3000-2500 yr ago and 8000-5000 yr ago. Several separate colonizations across Lake Michigan formed temporary outliers. No other pas outliers were detected, although modern outliers are known; however, even with closely spaced sites, outliers may have been undetected.

Published
1989

32. Ozone depletion, greenhouse gases, and climate change

Author

Mooney, Harold A, Baker, D. James, Jr, Bretherton, Francis P, Burke, Kevin C, Clark, William C, Davis, Margaret B, Dickinson, Robert E, Imbrie, John, Malone, Thomas F, and Mcelroy, Michael B

Subjects
Environment Pollution
Abstract

This symposium was organized to study the unusual convergence of a number of observations, both short and long term that defy an integrated explanation. Of particular importance are surface temperature observations and observations of upper atmospheric temperatures, which have declined significantly in parts of the stratosphere. There has also been a dramatic decline in ozone concentration over Antarctica that was not predicted. Significant changes in precipitation that seem to be latitude dependent have occurred. There has been a threefold increase in methane in the last 100 years; this is a problem because a source does not appear to exist for methane of the right isotopic composition to explain the increase. These and other meteorological global climate changes are examined in detail.

Published
1989

39. Holocene climate of New England

Author

Davis, Margaret B., Spear, Ray W., and Shane, Linda C.K.

Abstract

Stratigraphic studies of pollen and macrofossils from six sites at different elevations in the White Mountains of New Hampshire demonstrate changes in the distributions of four coniferous tree species during the Holocene. Two species presently confined to low elevations extended farther up the mountain slopes during the early Holocene: white pine grew 350 m above its present limit beginning 9000 yr B.P., while hemlock grew 300–400 m above its present limit soon after the species immigrated to the region 7000 yr. B.P. Hemlock disappeared from the highest sites about 5000 yr B.P., but both species persisted at sites 50–350 m above their present limits until the Little Ice Age began a few centuries ago. The history of the two main high-elevation conifers is more difficult to interpret. Spruce and fir first occur near their present upper limits 9000 or 10,000 yr B.P. Fir persisted in abundance at elevations similar to those where it occurs today throughout the Holocene, while spruce became infrequent at all elevations from the beginning of the Holocene until 2000 yr B.P. These facts suggest a more complex series of changes than a mere upward shift of the modern environmental gradient. Nevertheless, we conclude that the minimum climatic change which would explain the upward extensions of hemlock and white pine is a rise in temperature, perhaps as much as 2°C. The interval of maximum warmth started 9000 yr B.P. and lasted at least until 5000 yr B.P., correlative with the Prairie Period in Minnesota.

Published
1980
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43. A Study of East Tennessee Regional Phonology: Its Influence on Reading Performance

Author

Davis, Margaret B.

Subjects
Curriculum and Instruction
Abstract

The purposes of this study were to analyze the pronunciation of pupils and teachers to determine the deviation from the expected pronunciation for each group, and to determine the influence of dialect on reading performance of pupils. A random selection of twenty first grade, third-generation pupils and twenty elementary, second-generation teachers from four small, rural, all-white elementary schools in Sevier County, Tennessee were interviewed with the use of an instrument which the investigator developed from an arbitrary selection of one-hundred-sixty-two pictorial words. These words were teaching examples for the eighteen vowels and diphthongs that are taught as phoneme-grapheme correspondences in three leading basal reading programs. Each interview was conducted individually and taped on a reel-to-reel recorder. An informant (pupil or teacher) had only to look at a picture and say what it was. The material was transcribed from the tapes using the revised International Phonetic Alphabet and later compared with the teaching examples taken from the three basal reading programs. Any deviation from the expected pronunciation was counted as a "divergence" and the score for each informant became the number of such divergences. The divergence scores for both pupils and teachers were analyzed statistically, and the results indicated that neither the pupils nor the teachers pronounced the teaching examples according to the expected pronunciations to which they were compared, and that there is a difference between the speech of the pupils and the teachers. While the teachers tend to more closely approach the expected pronunciations, there is as much variation among teachers as among pupils. The pupils were administered a standard reading test (vocabulary part), and these raw scores compared to their individual divergence scores. The results showed a correlation coefficient of only -0.29. The lack of significant correlation between pupils' pronunciation and reading scores is taken to indicate that dialect differences in their phonological aspect are not related to reading performance.

Published
1975

45. Life of Abby Hopper Gibbons: Told Chiefly through Her Correspondence, vol. 2

Author

Gibbons, Abigail Hopper, 1801-1893 Author, Alcott, Louisa May, 1832-1888 Author, Sedgwick, Catharine Maria, 1789-1867 Author, Willard, Frances Elizabeth, 1839-1898 Author, Sedgwick, Elizabeth Buckminster Dwight, 1801-1864 Author, Morse, Lucy Gibbons, 1839-1936 Author, Hopper, Anna, fl. 1863-1874 Author, Gibbons, Julia, fl. 1862-1874 Author, Gay, Elizabeth, 1819-1907 Author, Rackemann, Elizabeth Dwight Sedgwick, 1826-1891 Author, Parkman, Sue Author, Watson, R. L. Author, Perlee, Mrs. Author, Townsend, Elizabeth G. Author, Palmer, Sarah A. Hopper Author, Parsons, Mrs. T. W. Author, Lowell, Josephine Shaw, 1843-1905 Author, Hunt, Elizabeth Author, Hepworth, Adaline A. Author, Barnard, Mrs. James M. Author, Sedgwick, Deborah W. Gannett, 1825-1901 Author, Davis, Margaret B. Author, White, Josephine B. Author, Emerson, Sarah Hopper Gibbons, 1835-1918 Author, and Gibbons, Abigail Hopper, 1801-1893 Author

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