The Conservation of Variety

Abstract

'And the vessel that he made of clay was marred in the hands of the potter; so he made it again another vessel, as seemed good to the potter to make it.' Jeremiah xviii. 4 E xcept in most of the ocean, the wildernesss is in retreat, or is" being changed in character. In another thousand years most of the world's surface and much of its fresh water will have been altered and fashioned by man ., or at any rate covered with living communities of plants and animals profoundly different from what they were even a few hundred years ago. Even where the outer form of vegetation has preserved a semblance of primitive character (as so often in forest after it recovers from fire or shifting cultivation), we must grow accustomed to the idea that its plant and animal populations (the latter mostly hidden from casual sight) will have changed their composition and their intricate struc­ ture and relationships. And all the time these communities will continue to be invaded by the species arriving from other parts of the world. So far the brunt of these invasions has been borne by the communities much changed and simplified by man. But some invaders are also penetrating the more stable and mature communities of ocean and natural forest. On the exploited lands of the world we see a decrease in richness and variety of species: monocultures with rigid spraying programmes ., pastures of pure grass populations, pure stands of trees, the replacement of strati­ fied and mature deciduous woods by quick-growing conifers with their relatively barren structure and poor inhabitants, the cleaning up of waste. patches ., the hormone spraying of roadsides ., and the planting of exotic species many of which may literally be quite sterile of animal life-at first. We ·might sum up this stream of events in the words of Isaiah: 1 5 4