Various kinds of organism living together in any habitat exhibit different types of interactions. Favorable climatic conditions and availability of suitable nutrients enable them to breed and flourish. The example of tropical forests can be taken here. A variety of flora and fauna grows luxuriantly here. The fauna, or animals, include bats, rats, rabbits, bears, deer, monkeys, tigers, snakes, lizards, frogs, many kinds of birds, insects and other animals.
The floras, or plants, include Sal trees, bamboo trees, different types of shrubs and creepers. In the water reservoirs, there may be crocodiles and several varieties of fish such as murrel, rohu, trout, carp, etc. a large variety of aquatic plants and animals may be found in and around water bodies of the forest. Each of these species finds the conditions suitable for its life. The entire system is self sustained and properly managed. This organizational unit of the biosphere is called an ecosystem. The ecosystem maintains a balance at different levels. In this balance the population level of a species or different species is maintained through the food chain and food web.