Air Photos and GIS |
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Air photos provide useful information about land undergoing restoration. In our area of Wisconsin we are fortunate in having a large array of air photos, both historical and current. The first air photos of Dane County, Wisconsin were taken by the U.S. Soil Conservation Service in 1937, as part of major efforts in soil erosion arising from the "dust bowl" period of the 1930s. Subsequently, air photos were taken in 1940, 1949, 1955, 1962, and with increasing frequency thereafter. At present high quality air photos are available from many sources. Georectified air photos of Wisconsin counties are available free of charge from Wisconsinview.org. Downloads of all available 1937 air photos are available gratis from the State Cartography Office. Geographic Information Systems (GIS) GIS is a broad term that deals with high-level mapping of spatial or geographical information. Pleasant Valley Conservancy uses industry-standard software from ESRI (Environmental Systems Research Institute) to display our air photos, maps, and field data.
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The 1990 air photo: changes wrought by time and neglect The air photograph shown below, taken by the Dane County Regional Planning Commission in 1990, provides a stark contrast to the 1937 photo.The original photo has been cropped so that only the prairie remnants and oak savannas are seen, to emphasize the differences. In 1990 the south-facing slope was almost completely wooded, except for a few small areas of prairie remnants. |
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After Restoration: A 2007 Air Photo The final photo in this sequence, taken September 1, 2007, shows what restoration can do. Using the 1937 air photo as a guide, we have returned Pleasant Valley Conservancy to a semblance of its original state. Of course, we have not been able to bring back "all" of the ecosystem. Many species of plants are difficult to establish, and may require many years of work. But most of the trees seen in the 1937 photo are still present today. Thus, in the 11 years of restoration work, dramatic changes have taken place. This should provide encouragement for others who might be interested in oak savanna restoration. |
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