Great Basin Naturalist


One hundred and twenty-eight mima mounds were studied relative to their vegetational relationships in a tall grass prairie area of central Iowa. Mound origins are thought to be due to several phenomena but are most likely initiated and maintained by the activity of pocket gophers. Seventy-five percent of the plant species common to the mounds are prairie species. When vegetative composition of the mounds was compared to the adjacent prairie vegetation, however, they were only 35 percent similar. The mounds were shown to alter the original structure and composition of the prairie vegetation. The mounds, once formed, created a new microenvironment. Many species were shown to respond to this new habitat. The factors deemed most influential in affecting the vegetational changes were disturbance and microrelief. Study observations indicate that the mounds represent microsuccession sites and cause changes in prairie vegetation to earlier stages in the sere.