Designing Habitats in Urban Environments - Design with the Desert: Conservation and Sustainable Development - page 384

22.2 Design Approach
22.2.1 Site Analysis
A site analysis serves as an evaluation of the opportunities and constraints of an area in
relation to the objectives of a project. It is critical that the initial scope of an analysis for
attracting wildlife is performed at a larger scale than intended for most created wildlife
areas. This is due to potential flows and interactions between transient wildlife and the
regional resources surrounding the proposed wildlife habitat site. Using a landscape
ecology approach to the initial site analysis is appropriate. In this approach, the focus
starts with the spatial patterns of the land uses in the urban matrix and the expected
interactions associated with existing land uses. For example, developed land, created and
natural open spaces, wetlands, and watercourses are evaluated and prioritized relative
to their significance to the purpose (species attempting to attract), size, and location of
the proposed wildlife area. These land uses should then be further categorized and
evaluated for quality of wildlife habitats based on an assessment of resources such as plant
communities and natural water sources.
Initial analysis at this larger scale allows recommendations to be developed relating to
connectedness of the habitat site with existing patches of habitat, appropriateness of habitat
location, and compatibility with the existing plant communities of a large metropolitan
area. For example, an analysis of Tucson at this larger scale would indicate various plant
communities associated with the Sonoran Desert scrub such as Arizona Upland and
Lower Colorado River Valley subdivisions. 4 These plant communities provide different
habitat benefits for a variety of wildlife. In urban areas, where such habitats are limited, it
is important to seek out opportunities where these plant communities can be preserved, or
perhaps recreated in a series of adjacent wildlife-friendly backyards. The habitat patches
that result from this type of connectedness can provide a significant respite for migratory
birds and support populations of native birds. 5
Further site analysis is also done at a local scale where evaluation of potential edge effects
between the wildlife areas and adjacent land uses are considered. Various studies have
shown the significance of edge effects on species diversity and population size. 6 At this
scale, the designer evaluates and prioritizes various locations in relation to these edge effects
such as natural watercourse and created park buffers adjacent to other land uses. Other
site-specific elements such as nearby water, roads, buildings, and existing vegetation are
considered for their microclimatic effects. For example, water from a natural source such as
a seep may provide water for wildlife and nearby plants whereas a swimming pool would
ameliorate site temperatures and provide a milder microclimate for frost-tender plants.
22.2.2 Vegetation Analysis
A more detailed analysis of vegetation is done following general plant community
assessment as described in the previous section (Table 22.1).
Ideally, species identification, structure (height), and density should be evaluated prior
to choosing a site for creating a wildlife habitat. This evaluation of existing vegetation
indicates its appropriateness for the wildlife species being targeted. For example, large,
existing, nonnative trees in Tucson such as eucalyptus ( Eucalyptus spp.) are considered
useful perches for raptors such as hawks and owls whereas Gambel's quail prefer the
cover provided by low-branching shrubs. 7 Therefore, depending on your goal, it might