THE NATURAL ENVIRONMENT

Earth hosts a huge life force. A vast, swarming, creeping, eating, breeding profusion that is so complex and vibrant that we still aren't even sure what defines it, let alone how to understand it. Through the complexity, however, certain patterns emerge, patterns that can be shown on maps.

If I ask you to imagine a desert scene, what comes to mind? Cactus? Camels? Bare sand and few plants? How about rainforests? Tall, wide-topped trees covering a shadowy forest floor? Hanging vines? Monkeys? These associations are rooted in environmental fact. Different climates support different kinds of plant and animal life. Vegetation, in particular, depends on the prevailing climate, and thus, climate and vegetation zones occupy similar locations on maps.

Animal life is less dependent on climate than on the history of dispersion, adaptation, and competition. That history has produced some amazing distinctions between the fauna of different places that can be broadly mapped.