It is widely accepted that many previously developed sites can significantly contribute to local and regional biodiversity. Previously developed land (PDL) can enhance existing biodiversity by providing habitats and linkages within urban environments. Specifically, PDL has a key role in urban habitat networks of open space, providing buffers for other, perhaps more sensitive habitats. It also has a role in increasing connectivity and supporting a diverse range of species, often including internationally and nationally protected species such as great crested newts and slow worms.

Typical PDL sites can include a range and variation of habitats to support biodiversity, such as bare ground, wetlands and open water, heathland, scrub, woodland, and grassland. The potential of PDL to support wildlife in urban areas can help achieve wider ecosystem resilience to withstand development pressures and the impacts of climate change.

Fact File – Ideal grassland environments

Mining spoil, slag, smelting and refining products can provide ideal environments for grasslands including calcareous (alkaline) and calamarian (metal-rich, typical of lead mining) which are valuable because of their botanical communities. Animals, or fauna, commonly found on PDL include insect (invertebrate) species and assemblages, reptiles and amphibians (herpetofauna), birds (ornithology) and mammal species.

PDL is often particularly valuable where disturbance and abandonment combine with other environmental (abiotic) factors, such as low levels of soil acidity (alkaline), supporting many diverse plant and animal species.


If open space is visually pleasing, comfortable and feels safe, it will be perceived as a quieter place to be (Environmental Protection UK). In an ICM survey in 2009, 9 out of 10 (91%) people interviewed believed that quiet areas need to be protected. Open spaces can provide refuge from busy urban environments where, even though noise levels may be high, the space will provide a more tranquil environment than surrounding built up areas.

 Air quality

Selective planting of trees and other vegetation can make a particular contribution to absorbing air pollutants helping to improve the urban environment and can provide buffering to help manage the visual intrusion of traffic.

Fact File – Open space and air quality

Tree planting appears to be an effective method for removing particulates inhaled by humans (PM10) from urban air. If a quarter of the urban land available was planted with trees, then average PM10 could be cut by between two and ten per cent. (Nolan, 2008)

One hectare of woodland would remove 50 kg of dust each year through deposition on tree leaves. (National Urban Forestry Unit, 1999)

In Glasgow, a 6% reduction in PM10 could be achieved by increasing tree cover from 3.6%to 8% . It is estimated that trees currently remove 4.9 ton (4.99 metric tonnes) of PM10 from the air in Glasgow.

In the West Midlands, trees currently remove 7% of the particulate pollution arising from human activity, or 39 ton (39.63 metric tonnes) of PM10 removed from the atmosphere. This is equivalent to a four per cent reduction in PM10 levels.

A toolkit is available from the forestry commission which measures the health benefits of urban trees. This toolkit assists in predicting the particulate matter concentrations before and after open space establishment. The tool uses air dispersion and particulate interception models (ADMS-Urban and UFORE) to predict the PM10 concentrations both before and after open space establishment. This has been demonstrated using a 10 x 10 km area of the proposed East London Green Grid.

(Powe and Willis, 2002)