Is wasteland a waste?

Recently surveyed an old allotment site in relation to a housing development that is proposed to go on it. As housing development goes, it's not too bad - apparently, they're willing to maintain the same proportion of the site in active allotment use as there is currently, albeit different plots, which they will clean up and make suitable for use as part of the overall works on site.

However, it raised a bigger issue in my mind. Which is - when is a site wasteland, in need of development as it is just underused, and when is it nature reclaiming what it had lost years before?

It was certainly an interesting place to wander and wonder in. About a third of the site was still in cultivation, with the rest having been left to go to waste about 20 or more years ago. Apart from the fact that I thought allotments were in short supply (and, admittedly, the selfish annoyance that people don't use them when many people, including myself, would love one), it was also an interesting slideshow into what happens to land left for twenty-odd years.

A scrub woodland was forming, with plenty of ash, birch, sycamore, hawthorn and the like spreading in from trees already present on the site and well as adjacent to it. There were scattered large poplars, willows and huge old hawthorns, in varying states of collapsing - yet in no way useless because of it. Brambles were choking every bit of ground they could cover (note to self: must get a billhook for such survey jobs). But most exciting were the remnants of what grew before - mature apple trees, once pruned into a neat and fruitful state but now going feral; branches going wherever they pleased, and yet still laden with fruit. Plum and cherry trees growing side-by-side with their thorny wild relative. A pioneer woodland coincidentally involving the growing trend for woodland gardening. And hidden away here and there - the remains of old huts, now with leaking rusted roofs and rotting timber. How long ago were they in use, busy with people sowing seeds in trays in early spring, warmed by a small fire in the corner?

Which makes me think - is this land truly abandoned, wasted, ripe for development because other the plots are just empty, useless space? Or is it an ecological experiment, combining the cultivated with the untamed, a boost for biodiversity in the middle of urban areas? Imagine such an area becoming a wild park, the antidote to manicured lawns and lollipop trees; somewhere where children play hide-and-seek or capture the flag, and foragers climb fruit trees with pockets increasingly laden with apples or clamber through collapsed trunks collecting oyster mushrooms.

However, on such an overcrowded island can we afford the luxury of 'allowing' such land to revert back to some semblance of nature? (Is it 'allowing' - who gave us the right to dictate such terms?) Should we leave urban, ignored areas to re-wild whilst claiming greenbelt land to "develop"? Which is more important to conserve, which has more value ecologically, and which is socially, economically, politically a better option? As always, no easy answer - but worth some thinking about.