Decreasing effectiveness of protected areas due to increasing development in the surroundings of U.S. National Park Service holdings after park establishment

Gimmi, Urs; Schmidt, Shelley; Gafvert, Ulf; Radeloff, Volker

Protected areas are cornerstones of biodiversity conservation, but protected areas are in danger of becoming islands in a sea of human dominated landscapes. It has been hypothesized that protected areas may even foster development in their surrounding area by providing specific amenities, thus partially causing the isolation that limits their functioning. The objective of our study was to assess road development and building growth within and around Indiana Dunes and Pictured Rocks National Lakeshores in the U.S. Great Lakes region before and since the establishment of these two parks in 1966 and estimate the effects of park creation on changes in landscape patterns. Roads and buildings were mapped for 1938, 1966 and 2005 from historic aerial photographs and topographical maps for both the park area and a 3.2 km buffer zone around each park. U.S. census housing density data from 1940 to 2000 were used as a baseline to compare observed changes with those in the broader landscape. Additionally, we applied morphological image processing to quantify the effects of building growth and road development on landscape fragmentation. Our results show that park establishment was effective in reducing and stopping the fragmenting impact of development within park boundaries. However, increased amenity levels following park establishment led to enhanced development in the 3.2 km buffer of both parks. In the extreme case of Indiana Dunes, building density outside the park increased from 45 to 200 buildings/km2 and road density almost doubled from 3.6 to 6.6 km/km2 from 1938 to 2005. The rates of change in this area were found to be much higher than in the broader landscape, particularly after park establishment. The potential amenity effect was up to 26,000 new buildings in the 3.2 km buffer zone around Indiana Dunes between 1966 and 2005. For Pictured Rocks the absolute effect was smaller but still half of the observed building growth was potentially due to amenity effects. Our findings highlight the need for conservation planning at broader scales, incorporating areas beyond the boundaries of protected areas.

Decreasing effectiveness of protected areas due to increasing development in the surroundings of U.S. National Park Service holdings after park establishment

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