Impacts of Residential Development and Amelioration of Biodiversity Impacts
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he purpose of this study was to demonstrate the value of urban areas to
protecting biodiversity. A common misconception is that urban areas and
biodiversity are mutually exclusive. The scope of this paper was to
identify what types of animals make use of residential areas and the
attributes that promote or discourage their survival. Twenty-seven diverse
residential sites in six different counties of the greater Chicago region
were selected to evaluate the features valuable to wildlife. A mix of
older and newer developments, some actively promoting the environment, was
chosen as part of the study. Residential housing densities ranged from 0.2
to 13.6 units per acre, and sites near Illinois Nature Preserves were
favored to increase the likelihood of observing animals.
The results of the study found that particular species of birds and
mammals are able to survive, and some to even thrive, within residential
areas. Field work and interviews identified 38 bird species, 35 of which
were native, within the study areas. A significant number of native
mammals also were sighted. Amphibians and reptiles did not fare as well in
residential areas and were only reported in ponds and retention basins.
Insects were found to have moderate levels of diversity. Regarding plant
life, 13 of the 27 sites had large oak trees that appeared to be native.
The results indicate that except for trees, native vegetation is much less
likely to survive in residential areas over one unit per acre.
Overall, the study finds that ponds, streams, and other natural or
naturalized water features are likely to increase the biodiversity in an
area and that many new developments, such as Prairie Crossing, have
included such features. Older residential areas tend to accumulate more
woody debris and have larger shrubs and trees than newer developments,
which also proves significant in promoting biodiversity. This is
apparently especially relevant to native mammals. The diversity of birds
is most directly related to the presence of wetlands and a diversity of
native vegetation. Reptiles, amphibians and invertebrates are most
dependent on the presence of wetlands.
These findings are significant in that they create the awareness that
urban areas are vital to the promotion of biodiversity, and that local
ordinances can encourage or discourage the prevalence of native vegetation
and open water features important to improved diversity. Developers can
actively plan and build in a way that enhances biodiversity by including
these features, while increased biodiversity in older residential areas
indicates the need to preserve these areas and maintain the
characteristics attractive to wildlife. Several new subdivisions studied,
including Prairie Crossing, Mill Creek, Hybernia and the Sanctuary,
increased the overall level of biodiversity by incorporating open water
into the development. In fact, the improved biodiversity of these
developments was used for marketing purposes. Overall, knowledge of the
features that preserve biodiversity in residential areas, combined with
adequate local regulations to preserve them, allows for those species most
suited to residential areas to reach optimal levels.
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