What Good Is Biodiversity?
There are hundreds of different kinds of birds in the tropics but less than one hundred bird species in an equivalent area of North America. The same holds true for all kinds of life. If you count the number of species of insects or plants or snails, you will find a bigger number in the tropics than in higher latitudes. It is not known why this is so, but that doesn't stop ecologists from arguing about it.
One common explanation is that more productive places will support a larger number of species. In ecological parlance, primary productivity refers to the amount of plant growth; that is, an acre with twenty tons of plants is more productive than an acre with only ten tons. So the ideea goes that more productivity can support a greater variety of animals, plants, bugs and fungi. With the unpredenented growth of the human population there are few places left on the Earth, land or sea, that have their full complement of life forms. There are about 10 million different life forms on the Earth; half of them may well be extinct in 100 years, primarily because of human conversion of their habitat. What will be the consequences of this biological holocaust to people?
We rely on our ecosystems to provide clean air, water, food, shelter, and fuel. Clearly, ecosystems cannot perform these services as well as they can if half their life forms have disappeared. Thus what would be an academic, theoretical debate among scientists about the effects of biological diversity on ecosystem function has become an argument with serious implications for our future. In crude terms the question is, how much damage can inflict on ecosystems before they stop functioning? We spoke with Michael Huston about this somewhat arcane but very important debate.