PARENT SESSION
Contributed Oral Session 1: Landscape History
Monday, August 8, 8:00 AM - 11:30 AM, Meeting Room 513 A, Level 5, Palais des congrès de Montréal

Landscape fragmentation due to housing growth in northern Wisconsin, USA from 1938 to 1998.

Gonzalez-Abraham, Charlotte^*,1, Radeloff, Volker¹, Hawbaker, Todd¹, Hammer, Roger¹, Stewart, Susan ², ¹ University of Wisconsin-Madison, Madison, Wisconsin, USA² USDA, Forest Service, Evanston, Illinois, USA

ABSTRACT- Houses exert a strong influence on ecological processes and landscape patterns. At the local scale, houses directly alter habitat, soil disturbance, introduction of exotic species and create barriers to animal movement, and at the landscape scale, houses fragment habitat. The amount of fragmentation depends on both the density and spatial pattern of the housing locations. Clustered patterns of houses creates overlapping disturbance zones and less fragmentation, while dispersed development affects a greater amount of area and has a greater affect on fragmentation. Few studies have quantified the spatial pattern of houses, how they change over time and what the effect that they have on landscape fragmentation. This study addresses two questions: a) how does the spatial pattern of houses affect landscape fragmentation; and b) how do houses and landscape fragmentation change through time? We mapped houses from historical aerial photographs for 5 time periods in northern Wisconsin. Patch level landscape metrics were calculated over the terrestrial area remaining after buffering each house with 100 and 500 meters disturbance zones. Using Ripley's K test we tracked in the change in the spatial pattern of houses over time. Our results showed a strong increase in the number of houses since 1938 and that the majority of growth was concentrated within 50 meters of lakeshores (up to 40 percent of the houses). In 1998, houses were not as strongly clustered (up to 35 percent of the houses) because development has shifted to areas farther away from lakeshores. Landscape fragmentation over time did not increase much, largely due to the clustering effect on lakeshores (< 0.1 percent loss of undisturbed area 1938 to 1998). However, the concentration of development in riparian areas affects sensitive habitats that are critical for many terrestrial and aquatic species. Our results suggest that zoning policies should promote clustering of new housing development and focus on protecting ecosystems most sensitive to development.

Key words: Landscape fragmentation, Housing growth, Spatial pattern, Northern Wisconsin