I was reading 'Bee Quest' last night, a fantastic book by Dave Goulson, who started the Bumblebee Conservation Trust.
He was describing the brownfield sites on the Thames Estuary and how they are much more biodiverse than greenfield sites, being as greenfield sites are mostly farmland and so heavily fertilised, pesticide-treated and fairly sterile, whereas brownfield sites are the opposite.
The unfortunate thing about these places is this: brownfield sites are often only surveyed just before they're ready to be developed. On some of these sites, really rare species or even new species are discovered, then have to be relocated before the area is built on.
As Dave Goulson points out, relocated creatures rarely succeed, as often we do not know their full habitat requirements, especially with the different insects. If we do know the habitat requirement, the species is relocated to an area of suitable habitat, which is likely to have that species present already and that habitat cannot support an increase in number of the same species, so roughly the same amount of creatures that were relocated there, die.
When will the powers-that-be wake up and realise that once they build on everything, and turn the rest of any land that's left into high-production farmland, heavily dosed with every chemical they can think of, we will have lost many of our fascinating insects and other creatures - and once they're gone, the other wildlife will suffer.
Gardens and allotments, when managed in a nature-friendly way, are crucial for our wildlife - and they even want to take these away from us!