Landscape change in an agricultural watershed in the US Midwest

Opportunities to improve the ecological functioning of agricultural landscapes in the U.S. Midwest exist, and could include the restoration of native plant communities to improve biodiversity or the modification of agricultural production systems to enhance the provisioning of ecosystem services to society. To be most effective in achieving these goals, restoration efforts require knowledge of past conditions and drivers of change. We assessed landscape change in the Clear Creek, Iowa watershed from 1940 to 2002 using five metrics derived from aerial photos: land cover composition and configuration, housing density and spatial pattern, and stream sinuosity. Major cover changes in the watershed included increases in urban (+1743.0 ha) and dense forest cover (+618.9 ha), coupled with a decline in the total area (-2773.4 ha) and mean patch area (-4.9 ha) of crops. Mean forest patch area increased (+3.7 ha), while patch number declined by 21.1% as reforestation linked small, previously isolated patches. Housing density increased dramatically, and houses were increasingly clustered across the study period. Most new houses were added in urban areas. Main stream channel sinuosity ranged between 1.49 and 1.27; mean sinuosity decreased by 0.22 from 1940 to 1963, a decline that persisted until 2002. In combination, changes in these five metrics document shifts in landscape composition and configuration that have important implications for people and the landscape. Our results indicate the dynamics of land use in the watershed, and may be used to parametrize hydrological models, in the development of future land use scenarios, and as a basis for restoration planning. (C) 2009 Elsevier B.V. All rights reserved.