Transcript Brownfield or Open Mosaic Habitat On Previously Developed Land

The
BROWNFIELD SITES
Approach
Key elements
•Shelter
•Bare ground and
early-succession habitats
•Flower-rich habitats
108 priority species are associated with brownfield sites. The
previous land use plays an important role in determining the
species composition of these sites. Some brownfield habitats will
qualify as the priority habitat Open mosaic habitats on previously
developed land. This is characterised by a mosaic of earlysuccession communities, friable bare ground and scattered scrub.
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•Scrub and scattered trees
•Sward structure
•Ecotones
•Large-scale mosaic
Management guides for this habitat
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Shelter
Shelter can be a difficult element to assess. However,
sheltered areas are generally those that are open to
direct sunlight but protected from excess wind by the
topography, vegetation, or buildings
Shelter provided by vegetation tends to occur in bays
of scrub and along site boundaries on ‘better’ soils,
or as areas of ruderal vegetation and scattered scrub.
South-facing slopes, and semi-circular bays of
vegetation open to the south, can be especially
important. Waste products and rubble can also
provide important shelter for heat-loving species.
Key determining factors:
•Topography
•Succession - scrub development
•Disturbance – scrub and tree management.
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Photograph: Tony Robinson
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Shelter – associated priority species
Many species on brownfield sites requires some
form of shelter. Examples, with their
requirements, are:
- heat at ground level; dense low
vegetation; humidity - soft-bodied prey; structural
variation.
•Grizzled skipper - nectar; foodplant (varied); bare
ground; sheltered locations (uneven topography or
within scrub).
•Long-horned mining bee – flower-rich areas;
stands of legumes; bare sand in sheltered locations
(uneven topography or within scrub).
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Bare ground and early-succession habitats
These are important components of brownfield sites of high ecological value, and are key features for
a site to meet priority habitat status.
Disturbance that removes vegetation creates areas of bare and sparsely-vegetated ground. Bare
ground includes industrial substrates, sand, exposed rock, and even small carpets of lichen and moss.
It invariably includes a scatter of early colonisers, many of which are food plants or provide other
critical resources such as nectar and pollen.
Soil that is over-compacted or churned is not
as good as well-drained loosely friable soil.
Bare or sparsely-vegetated ground adjoining
taller vegetation is often important.
Key determining factors:
•Disturbance – rabbits; erosion on tracks and
paths; operational disturbance.
•Substrate – hostile conditions may slow plant
succession.
Photograph: Samantha Davenport
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Bare ground and early-succession habitats
– associated priority species
Over 60% of priority species on brownfield sites are
associated with bare ground and early-succession habitats.
Examples, with their requirements, are:
- sparse sward and bare ground in a
mosaic; bird's-foot-trefoil (foodplant); nectar; sheltered
locations (uneven topography or within scrub).
•Streaked bombardier beetle – restricted to a couple of
sites - bare ground; rubble.
•Entire threadwort - metallophyte; bare ground; thin open
soils; dry conditions; old spoil - copper mines.
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Flower-rich habitats
Patches of tall flower-rich grasslands that are able to flower throughout the growing season can
provide a source of nectar and seeds. They are often best represented by sheets of common
flowering-plants, such as yellow composites and umbellifers. In brownfield sites there can also be
large areas of ruderal habitat dominated by herbs associated with disturbance.
The diversity of species and the nature of
management can also result in a complex
structure that includes tussocks and
sheltered bays within a matrix of other
vegetation.
Key determining factors:
•Disturbance - often found in areas such as
disused excavation or industrial sites. Best
managed by infrequent cutting that retains
some flower heads.
•Water/soil/air quality - substrate
Photograph: Dave Mitchell
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Herb-rich habitats – associated priority species
Around a half of all priority species on brownfield sites are associated with grassland. Of these about
a quarter require herb-rich foraging areas. Examples, with their requirements, are:
•Shrill carder bee - scrub edge and tussocks (nesting); tall-sward grassland; large-scale flower-rich
areas present spring-late summer.
•Large garden bumblebee – tall-sward grassland; large flower-rich areas in spring-late summer;
flowers with long corolla.
•Chalk carpet moth - calcareous soils; sparse thinly-vegetated ground or short turf; flower-rich areas;
disturbance.
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Scrub and scattered trees
Scrub is vegetation dominated by low, woody plants that typically forms an intermediate community
between open ground and woodland. Scrub that contains gaps and shrubs of different sizes is of much
greater value than scrub in large, homogenous blocks.
Occasional trees are beneficial as they
provide further structural diversity and
food sources. Species can use scrub and
scattered trees for shelter, feeding,
roosting and nesting.
In some brownfield sites scrub can be
plentiful, and it will be more important to
control it than to encourage it. Levels of
around 10% cover are appropriate for
priority habitat sites.
Key determining factors:
•Succession
•Disturbance - tree and scrub
management.
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Photograph: Tony Robinson
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Scrub and scattered trees – associated priority species
40% of priority species on brownfield sites are associated with scrub and scattered trees. Examples,
with their requirements, are:
•House sparrow - scattered scrub and grassland; garden/arable and hedgerow; colonial hole-nesting
species; close association with human settlements/farms; invertebrate food (for young in first week of
life).
•Dingy skipper - sparse sward and bare ground in a mosaic; bird's-foot-trefoil (foodplant); nectar;
sheltered locations (uneven topography or within scrub).
•Shrill carder bee - scrub edge, leaf litter and tussocks (nesting); tall-sward grassland; large-scale
flower-rich resource present throughout the year.
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Sward structure
Grassland swards on brownfield sites have a range of structures, each of which is important for
different species. Many species require more than one structure within a mosaic.
Short swards
Tall swards and tussocks
Open swards
Key determining factors:
•Soil/Air/Water Quality
•Disturbance
•Succession
Photograph: Tony Robinson
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Short swards
Short swards are those that are only a few centimetres high. On brownfield land they are often
found in a mosaic with bare ground. Extensive short swards are particularly favoured by vascular
plants, some invertebrates and by birds. In contrast, many invertebrates often require smaller areas of
short sward set within a mosaic of taller vegetation.
Key determining factors:
•Soil/Air/Water Quality - low soil
nutrient and/or extreme pH can
restrict plant diversity and growth.
•Disturbance – rabbits; erosion on
tracks and paths.
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Photograph: Tony Robinson
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Short swards – associated priority species
Over 55% of priority species in brownfield grassland are associated with short swards.
Examples, with their requirements, are:
• Lapwing - spring tilled arable land; extensive open short grassland; invertebrate abundance; wet
areas, pools with surface water and winter flooding.
•Wall butterfly - short grassland; bare ground; nectar; sheltered locations (uneven topography or
within scrub).
•Deptford pink - short grassland; herb-rich; unimproved; bare ground; well-drained.
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Tall swards and tussocks
These swards are particularly favoured by invertebrates and certain bird species. Tall swards are often
required all year round to provide a plentiful supply of nectar, pollen, food-plants, seeds, dead seed
heads and prey items.
Swards of common species in
herb-rich habitats can also provide
a very useful for resource for many
species.
Tussocks provide further structural
diversity and a microclimate very
different from their surroundings.
These, and tussocky areas within a
wider mosaic, should be
considered as very beneficial.
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Photograph: Samantha Davenport
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Tall swards and tussocks – associated priority species
Over 10% of priority species in brownfield grassland are associated with tall swards or tussocks.
Examples, with their requirements, are:
•Harvest mouse - tall grass throughout the year; bramble; rank swards.
•Large garden bumblebee – tall-sward grassland; large flower-rich areas in spring-late summer;
flowers with long corolla.
•Rampion bellflower – tall sward; rough grassland; waste ground.
Retun to Tall swards and tussocks
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Open swards
Open swards can be short or tall, but are characterised by open spaces between plants (as opposed to
a thick carpet of grass and other vegetation). These conditions are necessary for invertebrates and
some shorter-growing plant species.
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Photograph: Mike Lush
Photograph: Samantha Davenport
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Open swards – associated priority species
Over 55% of priority species on brownfield grassland are associated with open swards.
Examples, with their requirements, are:
– mosaic of vegetation with open
swards and bare ground; heat; invertebrates;
open habitats.
•Striped lychnis moth – tall and short open
sward; dark mullein (foodplant); rough downland
and roadsides, sometimes also in woodlands,
churchyards etc; disturbed bare ground.
•Caraway – open grassland; bare ground.
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Ecotones
These are the gradation between
two adjoining habitats, for
example grassland and
woodland. Ecotones should not
be severe; there should be a
gradual change from one habitat
to the other.
Key determining factors:
•Succession
•Disturbance - various types of
management that encourage a
transition from one habitat to
another.
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Photograph: Samantha Davenport
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Ecotones – associated priority species
Many priority species on brownfield sites are associated with ecotones. Examples, with their
requirements, are:
•Song thrush - gardens; field boundaries; woodland edge; scrub and adjacent open grassland;
invertebrate-rich damp areas (feeding).
•Red-shanked carder bee - scrub edge and tussocks to nest in; tall-sward grassland; large flower-rich
areas present from spring to late summer.
•Man orchid - herb-rich calcareous grassland; abandoned quarries; unimproved; scrub edge; well
drained.
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Large-scale mosaic
This refers to the juxtaposition of different habitats within a landscape. For example, wetland and
parkland or other green space adjacent to brownfield sites.
Such mosaics are largely required by
highly-mobile terrestrial species,
and can include both priority and
non-priority habitats.
Key determining factors:
•Scale
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Photograph: Tony Robinson
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Large-scale mosaic – associated priority species
Many priority species on brownfield sites are associated
with large-scale mosaics. Examples, with their
requirements, are:
•Brown banded carder bee – flower-rich habitat
(foraging); tussocky, undisturbed grasslands (nesting); well
connected landscape with high density of foraging habitat
(population survival).
- mature trees with holes or buildings (nesting);
short grasslands with invertebrates (feeding); cultivated
land/pastures/gardens (foraging in winter); woods and
reedbeds (roosting).
•Great crested newt - open fish-free, well-vegetated
ponds; high density of ponds in landscape; terrestrial
cover e.g. rough grassland, scrub and woodland; extensive
terrestrial habitat required.
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Management guides
Habitat creation handbook for the minerals industry
Managing brownfield and industrial land for bumblebees
Brownfields for butterflies
Buglife guides
Planning for brownfield biodiversity – a best practice guide
Managing aggregates sites for invertebrates – a best practice guide
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