Date of Award:

5-1-1985

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Biology

Department name when degree awarded

Biology Ecology

Committee Chair(s)

James A. MacMahon

Committee

James A. MacMahon

Committee

Michael Allen

Committee

Gene Wooldridge

Abstract

An evaluation of wind, small mammals and grasshoppers as dispersal agents of vesicular-arbuscular mycorrhizal (VAM) fungi was conducted in a shrub-steppe community disturbed by strip-mining in southwestern Wyoming. The capacity of each type of dispersal agent to move spores was assessed through survey and experimental sampling techniques. The collection of air samples, grasshoppers and rodent and grasshopper feces revealed that all agents studied carry VAM spores, especially in late summer. This pattern correlates well with the sporulation phenology of VAM fungi. While some spores recovered from rodent feces were germinable, those obtained from grasshoppers were not under the conditions tested. Spore dispersal agents were further assessed by excluding one or more of them from plots of ground and monitoring the change in spore density over the 1982 and 1983 field seasons. Plots where either mammals, or grasshoppers and mammals, were excluded did not have significantly different VAM spore densities in either year of the study. Generally, spore density decreased on the recontoured and topsoiled strip-mine during 1982, subsequent to the decomposition of residual spores, but began to increase in 1983. It is concluded that although some animal mediated spore dispersal occurs, the dispersal of VAM spores on a mesoscale basis is largely due to wind action in the ecosystem studied. An experiment to determine the source of the spores blown onto the study site was performed wherein deposition patterns of spore mimics released from two potential source areas were assessed.

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