Carrie Read
Friday, October 17, 2008 - 4:30-5:00
This study documents changes in the spatial patterns of prairie remnants from 1937 - 2005 within the Military Ridge Prairie Heritage Area (MRPHA), a 50,000 acre agricultural landscape in southcentral Wisconsin. The MRPHA has been identified as one opportunity to protect Midwest prairie remnants and the open landscape structure important to grassland-dependant bird and insect species. To quantify the spatial patterns of remnant prairies within the MRPHA, five regions and five time periods (1937, 1962, 1980, 1995/2000, and 2005) were selected to represent change over time. ArcGIS 9.1 software was used to digitize interpreted prairie from orthophotos. FRAGSTATS software was used to derive landscape metrics of prairie remnants for each region at each time period and these results were compared for each region as well as between regions to determine the temporal changes in spatial patterns. Between 1937 and 2005, all regions experienced a loss of prairie habitat which ranged from 44.7% to 86.7%. Increases in the number of prairie patches and decreases in the average patch size also occurred. All regions experienced decreases in mean the shape index, the cohesion index, and the clumpiness index. Changes in the spatial patterns of prairies have led to changes in the underlying heterogeneity of these remnants. Data from the regions examined indicate that prairie habitat in the MRPHA is occurring more often on steep slopes (>12%) and is more common on soils with moderate to low fertility and less common on soils with high fertility.
Keywords: Spatial dynamics, spatial patterns, land cover change, aerial photographs, geographic information system.