We know that a-diversity is less on remote islands and increases as we move towards the equator. However, there are exceptions to this general trend as illustrated by the following: (i) α-diversity peaks along gradient of productivity and declines in the most .productive systems; (ii) some taxa are more diverse in the north than towards the equator; (iii) some deserts have unusually diverse plant communities. We know relatively less about β-diversity to predict its current patterns or its future when the natural areas will be surrounded by highly modified habitats. β diversity depends on how large are species ranges and following two scenarios may be found: (i) If the range is large, α-diversity is independent of the area sampled, so that a national park to protect diversity can be placed anywhere. (ii) If α diversity is low, with species ranges being small (despite high total diversity) and non-overlapping, many parks will be needed to protect diversity.