Simulating the impact of human land use change on forest composition in the Great Plains agroecosystems with the Seedscape model

The expansion and contraction of marginal cropland in the Great Plains ofte n invoices small forested strips of land that provide important ecological benefits. The effect of human disturbance on these forests is not well know n. Because of their unique structure such forests are not well-represented by forest gap models. In this paper, the development, testing and applicati on of a new model known as Seedscape are described. Seedscape is a modifica tion of the JABOWA-II model, and it uses a spatially-explicit landscape to resolve small-scale features of highly fragmented forests in the eastern Gr eat Plains. It was tested and evaluated with observations from two sites, o ne in Nebraska and a second in eastern Iowa. Seedscape realistically simula tes succession at the Nebraska site, but is less successful at the Iowa sit e. Seedscape was also applied to the Nebraska site to simulate the effect t hat varying forest corridor widths, in response to the presumed expansion/c ontraction of adjacent agricultural land, has on succession properties. Res ults suggest that small differences in widths have negligible effects on fo rest composition, but large differences in widths may cause statistically-s ignificant changes in the relative importance of some species. We assert th at long-term ecological change in human dominated landscapes is not well un derstood, in part, because of inadequate modeling techniques. Seedscape pro vides a much-needed tool for assessing the ecological implications of land use change in forests of predominantly agricultural landscapes. (C) 2001 El sevier Science B.V. All rights reserved.