Greening the city : habitat evaluation in Wolverhampton.
Traditional evaluations of habitat quality fail in their spatial incompleteness, their lack
of contextual information and their poor consideration of urban environments. These
issues are addressed here through the derivation and application of an urban-specific
multi-criteria Habitat Value Index (HVI), providing relevant data in a straightforward,
rapid and replicable manner. Both the current distribution and projected changes in
landscape HVI are shown using the IDRISI Geographical Information System,
providing quantitative information to land-management decision-makers.
Using an urban-specific habitat classification in combination with aerial photographic
interpretation habitat patches were identified in study areas in the West and South of
Wolverhampton. The classification and location of the habitat patches were fieldchecked
then each patch was evaluated using four criteria: structural elements, indicator
species, general habitat structure and aesthetics. Using a tick-list approach the total
number of structural elements and indicator species from pre-determined lists was
noted in the field. General habitat structure and aesthetics were also evaluated in the
field with each patch assigned to a single category for each.
The criteria details for each patch were then transferred onto a GIS and for each
criterion a map was generated showing its spatial distribution over the study area. The
structural elements and indicator species totals were converted to scores based on scoreclasses,
while the categories for general structure, aesthetics and the specific habitat
type classification were used as weights by determining each to be either quality
(weight = 2) or non-quality (weight = 1). For each habitat patch the structural elements
and indicator species scores were then combined with the total weights to produce an
HVI. All the habitat patch values for the study area were displayed in map form to give
a contextual view of the distribution of ecological 'value' within the area. An
additional, simple measure was also devised for measuring the status and quality of
connectivity and contiguity within the study area. Sample criteria totals were then used
predictively to quantitatively demonstrate the effects of landscape alteration on both the
spatial distribution of the HVI and the connectivity and contiguity measures.