Date of Award
Doctor of Philosophy
Ecology and Evolutionary Biology
Kirk A. Moloney
Understanding the link between pattern and process is an important goal in ecology, and much research has focused on how small-scale disturbances act to produce spatial patterns in plant communities. In this research, I investigated the role of small-scale disturbances in structuring the plant communities of native and reconstructed prairies, with an explicit emphasis placed on understanding how spatial and temporal patterns in disturbance production affect seedling recruitment.;Two studies investigated the spatial and demographic effects of gopher mound production on four plant species in a native prairie. The spatial distributions of three species were positively related to the pattern of mound production, while the spatial distribution of one perennial grass species was unrelated. Seedling survivorship of all species was generally greater when growing directly on mounds than off mounds. Survivorship by seedlings growing on mounds was unrelated to the rate of neighborhood mound production, while survivorship by seedlings growing off mounds was negatively related. These studies provided evidence that mounds serve as sites for seedling recruitment into grasslands. Because mound production is spatially and temporally autocorrelated, these small-scale disturbances directly contribute to the formation of spatial patterns in native prairie plant communities.;Two additional studies were conducted as part of a large, landscape-level experiment to explicitly investigate how the spatial and temporal patterns in the production of small-scale disturbances affect seedling recruitment into reconstructed prairie. Seeds of forb species were planted on and off small-scale soil disturbances constructed to mimic gopher mounds. As predicted, seedling recruitment was greater on mounds than off mounds. However, there was no evidence that seedling recruitment was affected by the spatial or temporal patterns of mound production. In addition, there was some evidence that selective herbivory by small mammalian herbivores reduced the diversity of recruited seedlings, but herbivory pressure was approximately equal on and off mounds. The vegetation structure of the reconstructed prairies was different from that of native prairies, making it difficult to draw conclusions about the effects of disturbance production patterns on seedling recruitment into native prairies. Nevertheless, the studies provided important insights as to the similarities and differences in function of small-scale soil disturbances in native and reconstructed prairies.
Digital Repository @ Iowa State University, http://lib.dr.iastate.edu
Kelly S. Wolfe-Bellin
Wolfe-Bellin, Kelly S., "The role of small-scale disturbances in structuring the plant community of native and reconstructed prairies " (2001). Retrospective Theses and Dissertations. 463.