Earth is referred to as Biosphere – 1. Biosphere – 2 is a unique self-sustaining man-made artificial ecosystem, which has been constructed near Tucson in the Arizona desert (USA).
The building is airtight and encloses 3.15 acres area. It is totally independent except for sunlight.
It has a variety of natural living systems, which include a tropical rainforest, lakes, a desert, streams, freshwater and saltwater wetlands and even a small ocean with a coral reef. The structure has been designed to imitate the earth’s natural chemical recycling systems. Water that evaporated from its aquatic systems condensed as rainfall over the tropical rainforest. This water was supposed to provide freshwater for the living organisms before evaporating again.
Initially, in 1991, eight scientists (four women and four men) were completely sealed into Biosphere-2, for two years from the outside world. Besides, more than four thousand species of organisms were introduced. The scientists were supposed to grow their own food, breathe air generated by the plants and drink water produced by the natural recycling processes.
They succeeded in preparing 85% of their food. However, many problems were encountered from the very beginning. Large amount of oxygen disappeared inexplicably and additional oxygen had to be pumped from the outside. Many plant and animals species could not sustain themselves and became extinct.
Thus, an expenditure of 200 million dollar failed to maintain a life support system for only eight people. The earth i.e. Biosphere-1, on the other hand, supports billions of people, flora and fauna at no cost. So one can well imagine the value of different natural processes and the environment.
Species of plants and animals present in an ecosystem perform different functions. Role of each species is spoken of as its niche. In other words, the total role of a species in a community is the ecological niche. The ecological niche includes the species of organisms, environmental factors, the area in which the species live and the specialization of species population within a community. Every population has an ecological niche which determines the structure and adaptation of that population.
Ecological niche is not a simple concept but it relates the concepts of population and community. The niche is the property of the community which represents the place of the population in the community structure. Different communities in ecosystem characterised by similar environments are often similar in their structure and they may contain one or more niches that are essentially identical. The adaptations of population inhabiting these niches may also be similar, even though they are entirely unrelated.
Odum (1971) has classified the ecological niches into following types:
(i) Habitat niches:
These are concerned with habitats of the organisms.
(ii) Trophic niches:
These are related to physiological modifications.
(iii) Geographical niches:
These are related to geographical modifications.