The role of riparian vegetation is assessed quantitatively by using a five-decade record of valley bottom vegetation and channel dynamics developed from historical aerial photography. A 12-kilometer reach of a typical Ozarks stream was mapped using aerial photographs from 1938, 1948, 1955, 1965, 1976, and 1989; maps were then analyzed in a digital geographic information system. Analysis of sequential pairs of maps provides transition frequencies for assessing the relative areal rates at which riparian woodland, grassland, and cropland have been eroded or subjected to gravel aggradation. Results indicate that cropland and grassland have been no more likely to erode than woodland; cropland and grassland are slightly more susceptible to gravel deposition than woodland. These findings underscore the potential for complex responses of streams to a cumulative history of riparian and drainage-basin disturbances.