Ecology is the study of interrelationship between living organisms and their environment. Life and environment are interdependent. The plant and animal life is effected by various environmental factors and in turn they modify their environment in various ways. The main theme of ecological studies is the relationship between organisms and environment, so ecology may well be called as "Environmental Biology." Growth, development and destruction of all organisms is determined by physical and biological conditions, their extremes and their interactions. Environment determines the destiny of a living organism. Plants growing in any particular place fully adapt themselves to that habitat.
The term ecology was first of all proposed by Reiter, a zoologist in 1865. In 1866 Haeckel another zoologist defined ecology as the study of reciprocal relations between organisms and environment.
Divisions of Ecology
Ecology is divided into the following main divisions:
1. Autecology : is concerned with the study of individual plants or the population of individual plant species in relation to environment.
2. Synecology : is the study of plant communities and their relationship with environment.
3. Ecosystemology : In nature, plants do not live by themselves. Always associated with them are small and large animals belonging to different levels of food habits and evolutionary scale. As in the case of plants we have animal populations and communities. The plant and animal communities of any region influence and interact with one another and together constitute a biotic community. There is interdependence between plants and animals of a biotic community and an interchange of materials takes place between them. Thus a tree provides food and oxygen to animals. The animals on the other hand supply CO? for photosynthesis to green plants.
Dead plant parts and dead animals and their excretions serve as food for saprophytic fungi and bacteria and in this process are converted into organic humus component of soil. Due to further decomposition of organic matter, elements like Calcium, Potassium, Carbon dioxide, Nitrogen, Phosphorous, are released and returned to soil and serve as nutrients to plants. The biological community and nonliving environment thus interact with each other and an exchange of materials between them takes place. Such a natural unit of living community and nonliving environment interacting and exchanging material between themselves is called an Ecological system or ecosystem. Ecosystem is the functional unit of ecology.