Transcript Slide 1

Urban Green Network Mapping
in Brighton and Hove
Policy Base
PPS 9 paragraph 12:
“ Networks of natural habitats provide a valuable resource. They can
link sites of biodiversity importance and provide routes or stepping
stones for the migration, dispersal and genetic exchange of species
in the wider environment. Local authorities should aim to maintain
networks by avoiding or repairing the fragmentation and isolation of
natural habitats through policies in plans. Such networks should be
protected from development, and, where possible, strengthened by
or integrated within it. This may be done as part of a wider strategy
for the protection and extension of open space . . .”
Policy Base
PPG 17 paragraph 3:
“Local authorities should also recognise that most areas of open space
can perform multiple functions. . . . These include:
iii. promoting health and well-being: providing opportunities to people
of all ages for informal recreation, or to walk, cycle or ride within
parks and open spaces or along paths . . .
iv. havens and habitats for flora and fauna: sites may also have
potential to be corridors or stepping stones from one habitat to
another and may contribute towards achieving objectives set out in
local biodiversity action plans;
Wider context
SE Regional Biodiversity Strategy:
‘Biodiversity
Opportunity
Areas’
- rural areas only
Work on the Brighton and Hove network
began in Spring 2007
• Partnership between:
Sussex Wildlife Trust
Brighton & Hove Council
Geospec (GIS consultancy based
at Brighton University)
The study was divided into four tasks:
A) Define the functions of the network
B) Define the existing baseline of information for the network
C) Identify the additional
areas required to
complete the network
D) Peer review
The Functions of the Network
1. People-orientated function
- To take account of access to natural green space by people.
2. Species-orientated function
- To improve connectivity between habitats
3. Ecological services function
To promote air quality and
ameliorate the effects of
Climate Change (reduce
storm water runoff, urban
heat island effect, etc.)
- 3. Could not be progressed
Existing Baseline
1. People-orientated function
NE: “no-one should be further than
300m (in a straight line) from their
nearest natural green space.”
“Natural green space should be
provided at a ratio of not less than
2 ha per thousand people.”
Ordnance Survey’s Address
Point dataset was used to define
population density across the city.
Projected changes in population
to 2020 (LDF) were also taken
into account.
Existing Baseline
1. People-orientated function (cont/d)
- Brighton & Hove Open Space Audit 2007:
Existing Baseline
2. Species-orientated function
Designated Sites
- Sites of Special Scientific Interest,
- Local Nature Reserves,
- Sites of Nature Conservation Importance
Brighton & Hove Biodiversity Audit 2007
all areas of natural habitat in the urban
area and surrounding downland
- 25m2 or greater.
Additional areas
1. People-orientated function: Assumes land within 300m of natural green
space is the most appropriate for connecting spaces. Did not take account of
‘areas of deficiency’
Additional areas
Projected OS address point data then used to calculate future ‘population pressure’.
-300m buffer areas reduced to meet 2 ha /thousand people standard.
Additional areas
2. Species-orientated function:
Assumptions: Expert opinion used to define hypothetical ‘generic species’.
‘Generic reptile’:
maximum dispersal distance of 1km
‘Generic butterfly’:
maximum dispersal distance of 3km.
These generic species were designed to move progressively less easily
through increasingly urbanised habitats and features.
The species were not able to move through private gardens or over wholly
urban features (such as buildings and roads)
Additional areas
Generic butterfly
(used a logarithmic series ranging from 10 to 10,000,000 to assign permeability
values to different urban features)
The ‘final potential network’ was
defined by overlaying:
- All areas of natural habitat identified
by the Biodiversity Audit 2008
(the ‘Accessible Natural Greenspace’
layer)
+ ‘population pressure’ buffer areas
+ areas where the generic species maps
overlapped with the buffer areas
Overlays of NSN + population pressure buffer + ‘Generic species’ networks
‘Final potential network’ (red – light green areas from previous slide)
- overlaid onto a Brighton & Hove Open Spaces base map
Some interpretation required, using aerial photography and local knowledge,
to create ‘hard line boundaries’
Interpreted map – draft 1 (with thanks to the SBRC + Andrew Motley)
Map Detail
Green
Purple
Brown
Turquoise
= protected wildlife sites + existing natural habitat (‘core areas’)
= ‘potential core areas’
= ‘connection zones’
= other open space where biodiversity enhancement possible
Brown
= ‘connection zones’
Purple
= ‘potential core areas’
• Account for an additional 543.22 ha
• Amount of ‘NSN’ required by PMP study: 119 ha
- 4.5x as much!
– BUT:
• Most of the purple is beyond 15 minutes walk time
from the urban area
• Doesn’t address ‘areas of deficiency’ in NSN
• Hasn’t taken account of other potential land uses
Does address:
- Biosphere Reserve aspirations
- BAP habitat creation targets
Peer Review: Ongoing:
- BOA definition in Sussex
- WAG
- SEEBF & Regional Biodiversity Strategy
- LDF consultation