U.S. Department of Energy


Date of this Version



Published in THE PRAIRIE NATURALIST (June 1977) 9(2): 17-24


The study of seed dispersal between the widely separated forest patches (forest islands) of the eastern Great Plains can contribute to understanding effects of deforestation in the more complex forest island landscapes of the eastern United States. In the East, there is growing concern that the dissection of regional forests and the creation of small forest islands surrounded by non-forest uses (e.g., agriculture) may be affecting plant species richness and developmental patterns of vegetation (Levenson 1976), as has already been noted in the tropics (Gomezpompa et al. 1972). Curtis (1956) showed that the presettlement forest area in a portion of Green County, Wisconsin had been reduced by 70% as of 1882,90% by 1902,95% by 1935, and more than 96% by 1950.

The effect of distance in altering seed exchange between forest islands has not been directly tested. However, the use of forest islands as study sites has provided some clues about the effects of distance (isolation) on dispersal and forest composition. Scanlan (1975), Tramer and Suhrweir (1975), and Levenson (1976) all noted that the species richness of forest stands in Minnesota, Ohio, and Wisconsin, respectively, was inversely proportional to the degree of isolation from neighboring stands. It is not clearly understood whether the characteristics of deforested landscapes preferentially reduce the abundance of species with certain dispersal characteristics (e.g., heavy animal-dispersed and heavy wind-dispersed seeds).