Publication Date


Document Type


First Advisor

Meserve, Peter L.

Degree Name

M.S. (Master of Science)

Legacy Department

Department of Biological Sciences


Grasses--Illinois; Grazing--Illinois; Prairie ecology--Illinois; Microtus


A study of the effects of grazing by Licrotus pennsvlvanicus on the structure of the plant community in a restored Illinois tail-grass prairie was conducted in the summers of 1977-1978. The main species present on the study area were Andropogon gerardi, Sorghastrum nutans, Solidago altissima, and Eupatorium serotinum. The voles were excluded from two 50 m by 50 m plots by means of a fence 72 cm tall. Two control plots of similar size were also established. Vegetation was sampled every two weeks by clipping 10-0.05 m2 quadrats from each plot. The clipped vegetation was sorted into individual species and litter components. Dry weight biomass was determined by oven drying the vegetation at 70°C for 48 h and reweighing. Population levels of small mammals on the study area were monitored throughout the study by mark and recapture techniques. Population estimates were made by a minimum number known alive method. Differences between treatment and control areas for the biomass of the grasses were tested statistically using analysis of covariance. Biomass of the forbs, number of forbs and number of flowering culms were tested using nested analysis of variance. To test for differences between the treatment and control plots with respect to diversity the nonparametric hann-whitney U-test was employed. Results of the study showed that all species of plants (except E. serotinum) exhibited a trend toward greater biomass in the ungrazed areas. The difference in biomass between grazed and ungrazed areas was greatest for A. gerardi and grasses as a whole. Analysis of covariance revealed that the forbs on the study site were having a confounding effect on the response of the grasses independent of the effect of reduction in grazing. Diversity (H') exhibited a trend toward being greater outside the exclosures. Literature concerning microtine grazing is reviewed and similarities and dissimilarities are discussed in light of the present study. The conclusion is drawn that temporal patterns of growth and availability of the plant species influence the effect reduction in grazing will have on the plant community.


63 pages




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