Guidance note: biodiversity enhancements

Planting and Habitat Creation

Species-Specific

Water Habitats

§    The creation of wildlife corridors/linear features for wildlife movement.

§    Planting a new or enhancing an existing native species hedgerow.

§    Establishment of a wildflower meadow area.

§    Planting a new or enhancing an existing native woodland area or copse.

§    Using native plants in the landscaping design.

§    The addition of urban green infrastructure interventions (green roofs and/or green walls) to provide habitat for plants and animals.

§    Birds: provision of bird boxes or bricks for protected or priority species.

§    Bats: provisions such as open soffit boxes or access to loft spaces or installation of bat boxes or bricks.

§    Herptiles & small mammals: provision of refugia/hibernacula for reptiles and amphibian and small mammals.

§    Otters: creation of artificial otter holts.

§    Hedgehogs: hedgehog-friendly fencing, installation of hedgehog homes.

§    Invertebrates: Provision of insect hotels, pollinator-friendly planting and retention of deadwood.

§    INNS: Removal of invasive non-native species such as Himalayan balsam & Japanese knotweed.

§    Creation of a wildlife pond or wetland features.

§    Improving a waterway and its bank; creation of buffer zones along watercourses planted with native species of local provenance.

§    Naturalising/restoring watercourses and opening up culverts.

§    Providing biodiverse sustainable urban drainage systems which function as wildlife habitats, for example, swales and balancing ponds.

§    Marine enhancementssuch as increasing roughness of surfaces to support growth of marine communities.

Key Principles

Landscape design plans should (where possible and appropriate):

§    Recognise that habitat creation and planting are not acceptable substitutes for protecting existing sites of high wildlife value.

§    Consider the potential for natural regeneration - in some cases planting will be necessary to mitigate what may be perceived as unkempt.

§    Design your project well so that it can contribute to objectives laid down in the Swansea Local Biodiversity Action Plan/Nature Recovery Plan.

§    Plan ahead to allow contractors sufficient time to obtain plants and prepare the site.

§    Incorporate existing habitats and features into 'green spaces'.

§    Retain mature and veteran trees and hedgerows for their high biodiversity value - these will need to be monitored annually for safety.

§    Use 'public space' to demonstrate biodiversity benefits by using local provenance native species for wildflower meadows, woodlands, shrub borders and creating ponds, woodpiles etc. Access should be limited to one side of the habitat so as not to disturb wildlife.

§    Complement, rather than distract from, the localities natural countryside character and distinctiveness.

§    Promote 'Gardening for Wildlife' - choose plants that flower to encourage bees and butterflies; berries to encourage birds and different types of bark to encourage a wide variety of insects.

§    Use species-rich seed mixes for grassed areas.

§    Include additional biodiversity features, such as nest boxes, green infrastructure and wildlife-friendly boundary treatments.

Hedgerows and Woodlands

Hedgerows, treelines and woodlands are a valuable resource for wildlife and are a Section 7 priority habitat for conservation in Wales. Therefore, these habitats must be maintained on at least a like-for-like basis.

When replanting is required, native species should always be used, ideally of local provenance. Where translocation or creation is being used, consideration should be given to using the soil bank from the base of the existing trees/hedges that will be lost.

Existing hedgerows and woodlands can be enhanced by "gapping up" with extra planting or by employing an ecologically sensitive management regime.

The planting of new trees on a site, especially when connected to existing hedgerows/woodlands, can greatly increase the biodiversity value. At least 5 woody native species should be planted in order for it to be species-rich. Species could include: oak, hazel, hawthorn, blackthorn, holly, honeysuckle, guelder rose and wayfaring tree.

Hedgerows and tree-lines provide resting/breeding/foraging habitat for birds, dormice, amphibiansand reptiles and also commuting habitat for bats, badgers and otters.

These corridors should be kept dark in order to avoid disturbance to nocturnal animals using them.

Wildflowers

The creation of wildflower meadows provides an important resource for invertebrate pollinators, which then provide a food source for birds, reptiles, amphibians and small mammals.

Wherever grass seeding is proposed on a development site, a diverse mix, including wildflower species, should be considered, along with an appropriate cutting regime in order to maintain the diversity.

Nutrient levels in the soil will need to be kept low to encourage wildflowers, by using techniques such as cutting and collecting and minimal topsoil.

Green Infrastructure

Ecological solutions to engineering problems can provide opportunities for the enhancement of biodiversity. For example, Green Infrastructure solutions such as planting with native tree species to stabilise river banks, or using ponds as flood attenuation and reed beds for water filtration.

Green roofs and green walls can also benefit biodiversity, whilst providing other functions such as building cooling.

See the Swansea Council Green Infrastructure Strategy for further information: https://www.swansea.gov.uk/greeninfrastructurestrategy

Birds

Bird boxes are an effective means of biodiversity enhancement as bird boxes are inexpensive, easily installed and readily inhabited by a range of species. Target species within Swansea include: swift, starling, swallow, house sparrow, house martin and barn owl.

Allnew build developments will be expected to include integral bird boxes/bricks as an enhancement measure and a ratio of at least 1:1 nest bricks/boxes per dwelling is good practice. The inclusion of swift nest boxes/swift bricks are encouraged as these are known as the "universal" nest box/brick due to being readily used by other species, including house sparrows, starlings, house martins, blue tits, great tits and nuthatches.

Conversions/extensions/refurbishments:

Many bird species rely on cracks and crevices on houses to nest in. The more refurbishment works are undertaken, the less opportunities these birds have to nest. Therefore, bird boxes should also be included as enhancements for householder applications on existing buildings and especially barns and other agricultural buildings.

Bird boxes can also be installed on suitable trees, if no buildings are suitable.

Woodstone or woodcrete bird boxes are preferable over wooden ones because they are much more durable.

The location for a bird box will depend on the species it is targeting, but will generally need to be facing between north and east to avoid strong sunlight and the wettest winds, have a clear flight path and be away from disturbance such as lights, doors and windows.

The location and type of bird boxes must be shown on an architectural drawing and submitted to the LPA for approval. 

Bats

Like birds, many bat species rely on buildings for roosting in and so opportunities decrease as buildings are refurbished or demolished. Therefore, bat boxes or other provisions (such as access into loft spaces/soffits) should be included on all building developments, where possible.

Bat boxes can be fitted onto the outside of existing buildings or onto retained trees. Allnew build developments will be expected to include integral bat boxes/bricks as an enhancement measure.

Woodstone or woodcrete bat boxes are preferable over wooden ones because they are much more durable.

Bat boxes should be installed at least 4m aboveground, on a south-easterly to south-westerly aspect, have a clear flight path and be away from disturbance such as lights, doors and windows.

The location and type of bat boxes must be shown on an architectural drawing and submitted to the LPA for approval. 

If bats are present, a sensitive lighting strategy will also be required. This should follow recommendations in the 'Bats and Artificial lighting in the UK' Guidance Note, produced by the Bat Conservation Trust and Institution of Lighting Professionals: https://www.bats.org.uk/our-work/buildings-planning-and-development/lighting

Reptiles, Amphibians,  Small Mammals & Invertebrates

The inclusion of 'habitat piles' can enhance the biodiversity value of a site. This could be a purpose-built refugia using rubble and turf, a pile of brash from tree clearance or a pile of grass cuttings. Retaining deadwood on site is important as it provides habitat for many species of invertebrates and fungi.

Otters & Badgers

The creation of underpasses under new roads or green bridges over new roads can help to prevent wildlife casualties and also prevent fragmentation of habitats.

Underpasses/culverts are often targeted for otters and badgers, but can be targeted at smaller species such as amphibians and hedgehogs.

If there is a watercourse on or near the development site, then the inclusion of an artificial otter holt can be included as an enhancement. This can be as simple as constructing a refuge out of logs.

Hedgerow and woodland planting will enhance a site for both otters and badgers.

Hedgehogs

Hedgehog numbers have declined massively in recent years and it is thought that population numbers are still decreasing. The species is included on the Section 7 list as a Priority Species for Conservation in Wales. In July 2020, hedgehogs were added to the IUCN Red List for British Mammals, and are now classified as Vulnerable to extinction.

Domestic gardens are a valuable resource for hedgehogs, but garden fences act as a permanent obstruction to hedgehogs. To help address this habitat connectivity issue, all new development must incorporate hedgehog-sized gaps at the bottom of all new garden fences.

This can either be:

·         a continuous gap of 100 mm; or

·         squares of 130 mm x 130 mm at intervals which permit continued access and movement between adjacent gardens for foraging. More details provided in the specification drawings at the end of this note.

The Council require hedgehog highways and boundary treatments to be specified on an architectural plot drawing.

Invasive Non-Native Species (INNS)

INNS are capable of spreading rapidly and are a problem due to their ability to disrupt native habitats and ecosystems. INNS can outcompete native species, spread disease and interrupt the genetic integrity of native species.

If INNS plants, for example Japanese knotweed or Himalayan balsam, are identified on/near an application site then a condition will be placed on the planning permission for an INNS management plan to be submitted, detailing the avoidance/treatment/removal of such species.

The removal of INNS from a site will benefit the native biodiversity and can therefore be an ecological enhancement.

Creation of Wildlife Ponds

The creation of a wildlife pond benefits biodiversity as well as having other benefits such as flood attenuation and as an amenity feature. Pond edges can be planted or seeded with native species such as yellow flag iris, purple loosestrife, water mint and brooklime. The leaves of submerged aquatic plants are used by newts to lay their eggs in.

Wildlife ponds can also be created on a small-scale in a residential garden and will provide habitat forinvertebrates and amphibians and water for birds and small mammals.

Improving Waterways

Existing waterways can be improved for biodiversity in a number of ways, including INNS removal, litter removal, native flowering species planting and improving water quality by implementing pollution prevention measures or SuDS on the land that drains into the watercourse.

Wildlife-friendly SuDS

Drainage can be wildlife-friendly by including simple measures such as amphibian ladders to allow animals to climb out of gulley pots.

SuDS can be used to enhance a site for biodiversity by using native-species planting, for example. Further information on biodiversity and SuDS can be found in a separate Guidance Note[2].