Date of Award:

5-1-1982

Document Type:

Dissertation

Degree Name:

Doctor of Philosophy (PhD)

Department:

Biology

Department name when degree awarded

Life Sciences:Biology

Committee Chair(s)

James A. MacMahon

Committee

James A. MacMahon

Committee

D. R. Anderson

Committee

G. Bohart

Committee

K. Dixon

Committee

I. Palmblad

Abstract

This study addressed the relative importances of shrub "resources" on a rodent community in a sagebrush dominated shrub-steppe ecosystem in southwestern Wyoming. Direct effects of shrubs (i.e., providing rodents with "food and cover") were assessed by removing shrubs from a 1.25 ha study plot and monitoring both rodent populations and their food resources. Shrub-related "food and cover" was found to be unimportant to deermice (Peromyscus maniculatus), Great Basin pocket mice (Perognathus parvus), northern grasshopper mice (Onychomys leucogaster) and Uinta ground squirrels (Speromphilus armatus), as shrub removal caused no significant changes in population sizes, sex ratios or age structure. Least chipmunks (Eutamias minimus) responded to shrub removal by leaving the plot and moving into adjacent shrubland. The montane vole (Microtus montanus) population showed a slight increase following shrub removal. Shrub removal did not alter the abundance of major rodent food resources on the plot (percent cover of herbaceous vegetation, soil seed reserves and ground-dwelling arthropods). Micrometeorological data suggested that shrubs did not significantly ameliorate a nocturnal rodent's micro-climate. Therefore, the presence or absence of shrubs did not appear to directly effect most resident rodent species in this shrub-steppe ecosystem. Rather, shrubs may be important to rodents in a long-term time frame, by providing "safe sites" for growth of herbaceous vegetation, thereby enhancing the diversity of the potential rodent food resources.

Download

Share

COinS

Copyright for this work is retained by the student. If you have any questions regarding the inclusion of this work in the Digital Commons, please email us at .