Document Type

Thesis - University Access Only

Award Date


Degree Name

Master of Science (MS)

Department / School

Biology and Microbiology

First Advisor

Gerald A. Myers


The boundary between tallgrass prairie and forest represents an enigma that has long interested investigators of plants and soils. As wild areas under pressure of intensive land use come under protection to maintain their native ecology, there arises a concommitant need to understand their natural history. Solidified silica cells, called opal phytoliths, are a persistent signal of past vegetation. The abundance of phytoliths produced by grasses compared to deciduous trees makes them a quantifiable and morphological marker. Phytoliths were extracted from surface soils of a tallgrass prairie remnant bounded by oak forests. The relative abundance of phytoliths from soils across plant community boundaries was coupled with surface and subsurface soil pH and organic matter measurements to gauge the stability of the prairie-forest boundary. Pearson's correlation coefficient showed the relationship of opal phytolith amount and pH in forest and prairie soils to be highly significant (p = 0.01). Both variables suggest that a boundary of these two plant communities has fluctuated in the past. Soil type appears to influence the extent of forest migration into the prairie. Percent soil organic matter did not reveal a significant correlation to plant commmunity [sic] type. Microscopic examination of opal phytoliths seen in plant tissue residue corroborated phytolith shapes removed from soil samples.

Library of Congress Subject Headings

Soils -- Silica content
Plant communities
Prairie ecology
Forest ecology




South Dakota State University



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