Posted By: Halpin Robbins 8th June 2016
However, brownfield sites present a unique challenge as they can be areas of rich biodiversity, in some cases richer than local greenfields, containing priority species and habitats that should be or are afforded protection under UK law.
The reasons behind the potential rich biodiversity potential of brownfield sites are mostly due to the sites neglect and the quick colonisation by animals and plants of undisturbed and unmanaged areas. In addition, brownfield sites often have varied topography, due to historic disturbance such as excavations or soil movement, creating ponds, ephemeral water bodies, log piles, rubble piles and bare ground, all of which can be habitats to protected and notable species such as invertebrates, reptiles, great crested newts and plants. Derelict buildings, particularly those which have been unused for several years, are also favoured by roosting bats and nesting birds.
All these factors can, and do, create a lot of confusion with regard to species conservation and development with legislation and public opinion (generally) preferring to develop on local brownfield sites instead of green fields and conservationists advising that some brownfield sites are best left alone due to the habitat and species presence.
An example of such confusion over the value of brownfield site and the drive for development has been played out with the Streaked bombardier beetle (Brachinus sclopeta), one of only two kinds of bombardier beetle found in the UK.
Favouring the eastern Thames area of London the beetle has a preference for brownfield sites with relatively warm, dry conditions and thin soils, rubble and bare ground and is so rare that it was actually believed to be extinct in Britain in for 78 years as none had been seen since 1928.
In 2006 a colony was discovered on a site near the Thames Barrier that was scheduled for development. As planning permission had already been granted and the developer allowed conservationists time to move the colony, over 60 beetles were translocated to a new site nearby, consisting of rubble, crushed brick and concrete. It is believed that this population died out shortly after translocation for unconfirmed reasons.
In 2011, a new colony was found in Silvertown on a large brownfield site. This site also had planning permission but the development continued without the colony being translocated.
In 2012 Buglife discovered a new population in Newham, on a site that was due to be developed for infrastructure associated with the London 2012 Olympics. Buglife negotiated and worked with the developers to re-design the project’s layout, to retain the colony in its current location. This site is now the only known intact colony of the species in the UK.
The most effective option for all parties (planners, developers and conservationists) is to ensure that all sites, greenfield or brownfield, have their ecological values determined through careful ecological evaluation and assessment specific to the site and environment as the suite of ecological factors will differ for each. This should start with a Preliminary Ecological Assessment, containing historic records searches, and lead on to more detailed species and habitat specific assessments, as required, for all sites regardless of status.
There is also some confusion over the ecological impacts of staged development on green and brownfield sites, particularly when the superficial soils and structures are cleared and then the sub-soils are left exposed for long periods of time.
As previously mentioned the increase in biodiversity potential of a site is often due to the sites neglect and the quick colonisation by animals and plants of undisturbed and unmanaged areas. In staged developments when ground is cleared and materials stockpiled for long periods of time this can lead to colonisation by rare plants and animals and, in some cases, germination of a rich and diverse historic seed bank in the exposed soils.
A current example of this is found in Taunton, Somerset where planning permission was granted, in 2012, on a brownfield site for industrial and residential development. Development commenced with the demolition of existing structures on site, stripping and stockpiling topsoil and rubble and levelling of the site. The site was then developed in stages, starting with the infrastructure and residential properties; industrial areas and stockpile area were left undeveloped.
In 2016 these undeveloped areas are now covered in a wide variety of common and notable plants, reptiles, mammals and invertebrates. Whilst it is possible that most of these plants and animals have taken up residence since the clearance works commenced there are some species present that must have been within the historic seed bank of the site, such as Bee orchid (Ophrys apifera).
The original ecology reports are now out of date and the site is very different from its previous condition but there is not requirement in planning to resurvey the site or put mitigation in place. It is up to the developer and associated staff/employees to observe the requirements under UK legislation to look for, protect and/or mitigate for the presence of protected species that may have moved on to the site since the planning permission was granted. However it is often conservationists that stumble across these species and have to inform the developer of their presence or the local wildlife crimes officer of the species destruction.
Perhaps is should be a condition for staged developments to be resurveyd each year until the projects are complete?
Relevant Links
HalpinRobbins - Preliminary Ecological Assessments
Turas - Streaked Bombardier Beetle
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