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This study was designed to determine successional trends of soils and vegetation on Platte River islands in central Nebraska and to elucidate interactions between them through time.
Twenty study islands from five age-size classes were randomly selected in a 48 km stretch near Kearney, Nebraska. The age of islands wao determined by use of aerial photographs. Woody and herbaceous plant species were sampled systematically, and soil cores were analyzed for organic matter and texture at each island. Relative elevation at each sampling plot was determined.
There were 20 islands per linear kilometer in the study area larger than 0.04 ha (0.1 acre). Growth of islands was primarily due to merging of smaller islands and averaged 0.02 ha per year.
Tree stands were dominated by cottonwood and sandbar willow, and herbaccous stands by cocklebur. Stands were most often in a young successional stage regardless of island age. A trend toward more organic matter, finer-textured soils, and higher elevation occurred with older age. Species diversity and percentage of perennial herbaceous species also increased with age.
Flooding and drought seemed to account for the age structure of trees observed and probably for much of the soil structure and island growth.