Appendix II
Urbanization models evaluating
18 attributes in 38 regions
Four alternative spatial models (Figure 8.2) were superimposed on the 38 urban region
maps (Color Figures) to evaluate the effect of urbanization on 18 attributes measuring
natural systems and their human uses. Attributes covered by urbanization were counted or
estimated at each of the three time stages in a model. Amount recorded is an index of
effect or degradation due to urbanization. The four models were ranked accordingly
from best to worst (1 to 4) for each attribute in each region. See Table 8.2 for a summary
of Appendix II.
The models (see Chapter 8) are: C=Concentric-zones model; S=Satellite-cities model;
T=Transportation-corridors model; D=Dispersed-sites model. For Chicago, Philadelphia,
and Atlanta, the dispersed-sites model is ranked based on the first time stage only; see text.
A dash indicates that the attribute is absent or not mapped in the urban-region ring of
that city.
Asterisks indicate the following.Forest/woodland: overall estimate based primarily on forest/
woodland area covered, and secondarily on proximity to or fragmenting of forest/woodland.
Grassland/pastureland: same approach as for preceding.Desert/desertified area: same approach as
for preceding.Rivers/major streams: includes canals.Marine coast: along sea or bay.Reservoirs/lakes:
an estimate based equally on the percentage of reservoirs/lakes affected and the total length
of shoreline affected.Drainage area for water: refers to the area around a water-supply source
expected to be especially important for protection, rather than to a particular or complete
drainage basin/watershed/catchment.Average distance to major highway: interpreted as the
further development is from a major highway the more land is impacted by roads and
vehicles.Degree of subdividing region: overall estimate of disruption of connectivity for wildlife
movement across a region due to strip development and development in other locations.Edge
density: average length of built-area edge or border per unit area in the urban-region ring.City
center to metro area border: average distance from a point with in the metro area to its border
(the greater the distance, the less accessible surrounding countryside is to urban residents
and the less likely outside species will reach city greenspaces).Other attributes combined: letters
refer to the attribute present in a region; (a)=greenbelt; (b)=urban growth boundary;
(c)=Native Peoples’ land; (d)=aquaculture area; (e)=fire hazard area.