Date of Award

8-1984

Degree Type

Thesis

Degree Name

Master of Science

Major

Geology

Major Professor

Paul A. Delcourt

Committee Members

Hazel R. Delcourt, Thomas Broadhead, Steven G. Driese

Abstract

A 12 meter core of lacustrine sediments from Cupola Pond, Ripley County, Missouri, Provides the first continuous record in the Ozark Plateaus Region of ecologic changes from full-glacial time to the present. From 17,100 to 15,350 yr B.P., forest communities were dominated by jack and/or red pine (northern Diploxylon Pinus) and spruce (Picea). A late-glacial, transitional forest of oak (Quercus), ash (Fraxinus), pine and spruce characterized the upland vegetation that occurred during a period of climatic amelioration between 15,350 and 12,300 yr B.P. The early Holocene period from 12,300 to 9,100 yr B.P. was marked by the collapse of the northern Diploxylon pine, spruce, and ash populations, and the expansion of cool-temperate species of oak, hickory (Carya), and hornbeam (Carpinus/Ostrya type) as well as herbs of the family Compositae. Mid-Holocene warming between 9,100 and 6,700 yr B.P. brought about an apparent major decrease in the species richness of deciduous arboreal taxa. During a period of peak warming between 6,700 and 6,350 yr B.P., an oak park-land dominated the uplands (together, oak and grass (Gramineae) represented 92% of the upland-pollen assemblage). Buttonbush (Cephalanthus occidentalis) established around the shallow margin of Cupola Pond by 4,500 yr B.P. By 3,500 yr B. P., during the late-Holocene interval, the upland vegetation of oak parkland was replace by a forest dominated by shortleaf pine (southern Diploxylon Pinus). By 3,300 yr B.P., as temperate forested environments replaced the more xeric parkland environments in the uplands, populations of tupelogum (Nyssa aquatica) locally established in the bottomlands around Cupola Pond.

The sequential migration of tree taxa during the late-glacial and throughout the Holocene reflects both a biotic response to climatic change, and differences in rate and routes of migration from full-glacial refugial areas. However, taxon calibrations and modern analogues (using dissimilarity coefficients of Euclidian Distance, Standard Euclidian Distance, and Chord Distance), indicate that the Southeastern Ozark Plateaus provided a full-glacial refuge of cool-temperate deciduous taxa, including oak, maple (Acer), ash, elm and willow (Salix).

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