What is it?
Brownfield sites have been previously developed and then abandoned, or had the soil removed or changed by the addition of things such as slag, coal spoil or other products of industry. The resulting mix of exposed concrete, bare ground and rubble provides excellent habitat for a variety of species. Many of the species that will live on these sites are ones that have become rare in the wider landscape due to a lack of open, early successional habitat (the first stage in a habitat’s journey towards becoming a forest).
Sometimes referred to as “open mosaic habitat”, brownfield sites are generally made up from a mix of bare ground, short grassland, patches of ruderal (weedy) tall herbs, longer flower-rich grassland, scrub and temporary pools. Combined with derelict infrastructure and little intervention from people, these places are ideal for invertebrates. They provide nectar, sheltered warm areas, opportunities for burrowing and good foraging habitat. Brownfield sites can be good for reptiles, with plenty of basking areas and cover.
Why is it like this?
Exposed substrate, spoil heaps, broken bricks and concrete create drought-prone and nutrient poor soils – just the thing for species dependent on early successional habitats. Such habitats are increasingly rare elsewhere. The nature of the soil means that, although lush vegetation may develop in places, open bare areas can persist for a long time.
The varied history of brownfield sites means that there is much variation in the pH and chemical composition of the soils. This creates a great deal of variety across the range of the habitat.
Distribution in the UK
The area of brownfield in England is thought to be about 35,000ha; its extent is not known in Scotland, Wales and Northern Ireland.
What to look for
Bees, wasps and hoverflies can all be seen feeding on the nectar and pollen of flowering plants. Rare species such as the shrill carder bee now rely on brownfield sites. Slow worm, common lizard, adder and grass snake may all be present and pools can support newts and common frog. Butterflies may include dingy skipper and grayling. Orchids, such as bee orchid and fragrant orchid, can also be found.
Re-development is always a threat on brownfield sites. Few have legal protection and their diversity makes them hard to define and assess. Ways to ensure the long-term continuity of the habitat need to be explored. You can help by taking an interest in brownfield sites near you. If you notice particular or rare species in a local brownfield site report this to your local environmental records centre or Wildlife Trust.