Ecology

Definition
Ecology is the scientific study of different relationships with each other and with their non-living environment which supports them.
Levels of Organisation of Ecology
Starting with individual organism, there are several levels at which interactions between the organism and their environment can be studied. These levels of study are
1. Population
2. Community
3. Ecosystem
4. Biomes
5. Biosphere
1. Population
A group of organisms of same species living and interacting in the same area is known as population. In other words members of the same species in an ecosystem constitutes a population. Population ecology mainly deals with factors that affect population size and composition.
2. Community
The next level of ecological organization is a community. It consists of a group of organisms (plants and animals) belonging to different species which interact in a particular area. In other words members of different species in an ecosystem form a community. Community ecology studies various interaction such as predation and competition among different species.
3. Ecosystem
It is higher level of ecological study and includes both abiotic factors and community of species of a particular area. Ecosystem is the basic structural and functional unit of ecology. It consists of a community of living organisms which interact with each other and also with their non-living environment to maintain equilibrium of life. Ecosystem ecology deals with study of the flow of energy and cycling of material between biotic and abiotic components of a particular area. The ultimate source of energy for any ecosystem is the sun. Examples of a ecosystem are a pond, a lake, ocean, forests, desert etc.
4. Biomes
Biomes are assemblage of large and similar ecosystem which cover vast geographical areas of the earth. For example coniferous forest biome includes all the comferous forest ecosystems which extend across the Europe, Asia and North American continents. The desert biome includes an extensive desert area scattered over many regions of the earth. Biome can also be described as a large easily recognisable community unit which is spread over vast geographical areas. Although a biome includes many species of plants and animals, it is primarily identified by its plant life and is named after a predominant vegetation, known as the population. For example forest biome or grass land biome. A biome is also named after some environmental factor. For example ram forest or temperate grass land.
5. Biosphere
All the ecosystem and biomes collectively form the biosphere. In other words, the entire portion of planet earth where life is present is called biosphere. Biosphere consists of the earth from its surface to about few meter depth, all the water and the gaseous capsule surrounding the earth. The surrounding air envelop extends to about two mile above the surface of earth. Beyond the biosphere, no living organism can survive.