Master's Theses

Document Type

Thesis - campus only access

Date of Award

Spring 1969

Degree Name

Master of Science (MS)




Dr. Eugene Flaherty


Vegetational clipping remains, resulting from Sigmodon hispidus activity in a relict grassland area, were collected and analyzed for vegetational composition, dry weight, and caloric content. Monthly Sigmodon population densities were determined and correlated with monthly clipped vegetation. During the one year study period, Sigmodon clipped 315.05 kg of vegetation on the 4.85 hectare study area. This amounted to 136.4 x 104 kcal. Grasses (mainly Andropogon gerardi, A. scoparius, and Bouteloua curtipendula) accounted for 54% of the vegetation clipped, Ambrosia psilostachya and Kochia scoparia 40%, and Helianthus annuus 6%. Seventy-two percent of the clippings occurred in the fall (Sept-Nov.). The amount of clipped material/Sigmodon/month varied from zero in May to 1.303 kg in October. The amount of material clipped may not be solely dependent on a high Sigmodon density, but possibly with the condition of the vegetation and nest building activities of the rat. Of the net primary production in this area during the study period, 0.39% was clipped by Sigmodon.


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© 1969 Yaroslaw Petryszyn

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