Date of this Version
A dissertation submitted to the Faculty of the Graduate College of Oklahoma State University in partial fulfillment of the requirements for the Degree of Doctor of Philosophy, December 2010.
I. FIRE-RESILIENCY OF A NORTH AMERICAN ARTEMISIA (ASTERACEAE) SHRUB: IMPLICATIONS FOR RESTORATION OF A CRITICAL ECOSYSTEM PROCESS. Conclusions: Unlike most North American Artemisia shrub species, our research suggests that A. filifolia is highly resilient to the effects of fire. Therefore, use of prescribed fires for the restoration and maintenance of ecosystem processes and properties is appropriate in A. filifolia shrublands of the southern Great Plains in North America.
II. RESTORATION OF THE FIRE-GRAZING INTERACTION IN ARTEMISIA FILIFOLIA SHRUBLAND OF THE SOUTHERN GREAT PLAINS, NORTH AMERICA. Synthesis and applications. Vegetation structure in Artemisia filifolia shrublands of our study were readily altered by the fire-grazing interaction, but they also demonstrated substantial resilience to these effects. The fire-grazing interaction also changed the total amount of heterogeneity characterizing this system, the scale at which heterogeneity in this system was expressed and the amount of heterogeneity expressed through time. Restoration of the fire-grazing interaction resulted in a shifting mosaic of habitat conditions that is likely important to the conservation of biodiversity within this ecosystem.
III. TOPOEDAPHIC VARIABILITY AND PYRIC-HERBIVORY: EFFECTS OF INHERENT VS. IMPOSED HETEROGENEITY ON VEGETATION STRUCTURE. Pyric-herbivory is the interaction of fire and grazing across multiple spatial and temporal scales resulting in a shifting landscape mosaic of patches that differ in the amount and intensity of disturbance. We examined effects of pyric-herbivory on vegetation structure and animal distribution across contrasting topographical sites in Artemisia filifolia shrubland of the southern Great Plains in North America. Our results indicate that landscapes at our study site were characterized by an inherent amount of heterogeneity in vegetation structure due to variability in topoedaphic sites while the pyric-herbivory treatment superimposed an additional layer of heterogeneity that was constrained by topoedaphic characteristics. We were unable to detect an effect of topoedaphic site or the pyric-herbivory treatment on animal distribution, but our results suggest this was due to insufficient replication of study sites.