While it's true that the vast majority of the planet's surface is still unpopulated, by and large cities spring up where the living is easy: on the most ecologically fecund land. And as those cities sprawl out, they tend cover more and more of that land over with pavement and buildings.
More and more, but not all. A fairly high percentage of most urban areas remains open, but fragmented: gardens, yards, alleys, vacant lots, etc. If we want to green our cities, we need to find ways of making those fragmented pieces of land serve natural as well as human ends.
Here's a great example of how to do that: Wild About Gardens, a joint project of the Wildlife Trusts and Royal Horticultural Society, which aims to both promote wildlife gardening (or "backyard biodiversity") and build a broader base of knowledge about which practices work best and why:
Have you ever really looked at what's going on in your garden? How many wild creatures are there? What do they do? What do they feed off? What plants do they like best? Where do they nest? What wild plants make their way into your garden? Have you ever wondered where these wild creatures come from, and whether there are as many of them in the next town or county?
The UK has 15 million gardens covering 270,000 hectares. That's more than all the National Nature Reserves in the UK. This means that gardens are really important for local wildlife. A mosaic of friendly gardens provides a variety of habitats where creatures can find everything they need to feed, drink, shelter and breed. However small, every little patch counts. Even a window box or a container can provide a welcome stop on a long journey.
We'd like to build up a source of local knowledge about wildlife in gardens, and this is where we need YOU. You can provide us with valuable information about the wild creatures and plants in your garden.
The best thing we can to preserve wildlife is not to sprawl in the first place, of course, but cities -- and lots more of them -- are the 21st Century reality. Given that, learning how to garden responsibly across the entire landscape is a pretty vital skill. Every lawn a little meadow, every street a linear forest...
(Thanks, Garry, though I still can't hear the word "horticulture" without thinking of the Dorothy Parker line
NPR had a great story Florida County Seeks to Redefine the Wildlife Refuge a few weeks ago on this topic. In a nutshell, Broward County is working to get homeowners and municapilities all on board with creating true urban habitats — in their yards, easements, parks, etc. Great example of how people can work together to create a region more hospitable to biodiversity.
A good book (for people like me, with only tiny urban guerrilla plots to work with):
Gayla Trail's very new You Grow Girl, which beautifully illustrates gardening for urban dwellers. Covers organics, community gardens, plants and containers on fire escapes...
We practice "co-gardening." We've had a large (1/2 acre, 0.2 hectare) organic garden for 17 years. About 15 years ago, we began sharing it with friends. We now have 10 folks gardening together. It's not a "community garden" with individual plots; it's one large garden, planted to what we all agree to grow, worked on by all of us. Each of us is good at something: tilling, weeding, planting, harvesting, fixing tools and machines. We have "work days" that usually include a mid-day meal together. Folks are also free to come and go according to their schedules. We organize by phone and email; people know what's expected of them, and we rarely have slackers. It works well for us, and I think at least half the folks in our group wouldn't have gardens otherwise. It's fun exercise and socializing, and it sure beats mowing the lawn.