Change detection and landscape metrics for inferring anthropogenic processes in the greater EFMO area

摘要

Remote sensing offers an important means of detecting and analyzing temporal changes occurring in our landscape, This research used remote sensing to quantify land use/land cover changes, and landscape metrics to track ecological impacts of such changes at the Effigy Mounds National Monument (EFMO), Iowa, USA. Aerial photography spanning a period of six decades, IKONOS pan-sharpened (1 × 1 m) data, and input from the US National Park Service were used to develop land cover classification maps for the 1940s, 1960s, and 1990s. A post-classification algorithm was applied to derive land cover changes, and landscape metrics were used to analyze specific habitat classes. Overall changes in natural vegetation between 1940s and 1990s at EFMO showed interchangeable shifts whereby the canopies of some areas of deciduous forests and bottomland woodlands thinned out, whereas others transited from croplands in the 1940s to full growth forest in the 1990s. Similar patterns were observed for cropland and pasture, where the total area of cropland declined while that of pasture increased, albeit with a decline in the number of patches. Land cover changes around EFMO reflect the impacts of management decisions made in response to shifts in agricultural and economic policy while, within EFMO, the areas of "natural" vegetation are well maintained and devoid of any significant human activity.