The temporal dynamics of riparian forest stands in the American Midwest are examined for different conditions of climate, river flow, and soil type. Spectral analysis is performed on tree densities, and changes in the basal area of species are also analyzed. Different spectral densities are found. The dynamic behavior of forest stands can be attributed primarily to the life history traits of the dominant species; in different environmental conditions, different dominant species result in different cyclic responses of stand-level variables. In the simulation, warmer and/or drier conditions would result in a more diverse forest with less distinct cyclic behavior than in cooler and/or wetter conditions dominated by one or two species. Within the more diverse community of warmer conditions, differences in the competitive abilities of species at different stages of asynchronous life histories may explain the dynamic behavior of stand-level variables.