There are three basic levels of diversity of life:

This relates to the issue of the widespread practice of growing single crop varieties over a large area (monocultures), or intensively farming single varieties of animals. If disease strikes, it is more likely to decimate the whole population. We mostly use the term diversity to mean the diversity of species and the abundance of individuals present, and it can be used as a measure of biological health of a habitat. In general, a stable habitat has a wide range of different species, each with a fairly small number of individuals (e.g. an undisturbed meadow). A less stable habitat, i.e. one which is under stress from pollution or major disturbance, etc., has just a few species, but each with very large populations (e.g. a school playing field). Regular monitoring of species diversity in a habitat can be useful in assessing levels of damage or improvement, and identifying any causes of environmental stress.

The term biodiversity is used to describe the biological diversity or variety of life on Earth. Ecologists generally agree that it is important to maintain biodiversity and try to avoid extinction of species. Due to the close inter-dependency of organisms in a habitat, the disappearance of one species will affect the others in the food web. There are also ethical, aesthetic, medical, and industrial reasons proposed for conserving species. Extinction is a natural product of the evolutionary process, and many more species have disappeared than exist today, but the real concern is that rate of extinction has been greatly increased as a result of human activity (e.g. habitat destruction, pollution, hunting, war, and the effects of introducing species from other habitats).


Diversity of organisms
Ecosystems and habitats
Species interaction
Self assessment (1)
Self assessment (2)