On a colleague's blog, he has posted a video of his search for biodiversity in his church garden.

Reminds me of the project some years ago, a year or two after the first Earth Day, when there was a biodiversity search in London, England.

We found the most amazing plants growing in the grassy islands in the middle of major roads - some at traffic circles (roundabouts), some just traffic dividers. They were not native to Britain, many of them were African, tropical. What was going on? A search of nearby gardens revealed no such plants. Where had they come from?

Then, aha, there she was, an old lady, feeding the birds. One of many folks looking after the wild life that's trying to find a way to survive in our urban creations. Many of these plants would not, of course, survive the winter -- but even then their cousins might well be back next year as new birds were fed by new human neighbors.

Biodiversity is not always, however, a cause for celebration. The spread of biodiversity due to human actions is not always beneficial. Think of the fleas on the rats bringing plague to Europe.

Indeed, today London faces another "plague", this one precisely in the realm of plant biodiversity. It is Japanese knotweed, originally brought to England as a decorative plant by Victorian gardeners. We had a bit in our garden in London, and man, "hardy" doesn't begin to describe it. It grows so quickly you can almost see it. It's roots (actually rhizomes) quickly extend more than 20 feet in all directions, and nearly 10 feet down. And even if you pull it up as soon as it shoots, unless you get every little scrap of root, even if only about half a gram of root should remain down there somewhere, the whole thing will grow again.

It will happily invade your house (see above), and your drains. Worse, they have discovered an amazing mass of acres of the stuff just where the Olympic stadia etc. need to be built for the London Olympics in 2012. It will have to be dug out, and all the soil replaced. Herbicides are not an option, as it requires several years of herbicide application to eradicate this hardy import.

Cost overruns for the Olympics are legendary, but London's look to be stratospheric. Just eradicating the knotweed will cost millions of pounds, but if they don't do it, the stadia will just break up from underneath. Wow! Sometimes I have to love it when the earth fights back.