The variety of living organisms living on the earth is referred as biodiversity or biomes.
Bio-diversity is the presence of a number of different interacting life forms in an eco-system. There are pressures to reduce bio-diversity in the modern world. As examples, many agricultural areas have become mono-cultures of a specific crop (e.g. corn) to the exclusion of all others to allow ease of cultivation and harvesting, and people tend to want to limit the species in the areas they live to "favorable" types e.g. they would eliminate mosquitoes from recreational areas.
This creates a problem as a diversity of species is essential to maintain predator prey relationships, degrade waste materials, pollinate crops, prevent the rapid spread of disease and maintain a genetic diversity in individual species. terms like web of life or food chain are often used to describe this relationship.