DEFINITION AND SCOPE

The term ecology is derived from the Greek "oikos " meaning 'habitation' or 'house'. It refers to the living place of life.  Ecology is the study of organisms at home which is called as the environment. The terms life and environment are inseparable. The Science of Ecology involves: The study of the relation of organisms or a group of organisms to their environment and the study of the totality of man and his environment. Ecology is Environmental Biology. It is well known that Biology is the science of life. Since ecology also deals with the life and its surrounding conditions, it is also called as “ Environmental biology”. 

Ecology deals with:

1. the spatial distribution of an abundance of organisms

2. the temporal changes in the occurrence, abundance and activities of organisms

 3. the interrelations between organisms, communities and populations

4. the structural adaptation and functional adjustments of organisms to the change in environment,

5. the behaviour of organisms under natural environment, the productivity of organisms

6. energy and other natural resources to mankind and

7. the development of interactive models for analytical or predictive purposes.

ENVIRONMENTAL INTERACTIONS

 Ecology deals with organisms, populations, communities, ecosystems and the biosphere. A lot of interactions between the life and the surrounding conditions and among the organic world are expected to happen at all time. Several types of interactions may happen between 

a. an organism & its place of living,

b. an organism & its neighbor

c. an organism & its own community,

d. an organism & other communities,

e. a group of organisms & an organism and

f. a community to a community.

 MAJOR SUB-DIVISIONS

In general, ecology is classified into two major divisions:

Animal ecology : This branch deals with the animal population, its changes, their bahaviour, and their relationships with the environment.

Plant ecology : This branch deals with the relationships of plants to other plants and their environment.  It is known that all animals mostly depend on plants for both food and shelter. Hence, animal ecology deals with both animal and plant communities.

Due to these, the science of ecology is divided into

a) synecology 

b) autecology, based on the organism and habitats.

SYNECOLOGY:

This branch deals with the study of groups of organisms or the community. This is a habitat based study. A habitat is a place where an organism or species population or a community thrives. There are two major habitats as 1. terrestrial habitats and 2. aquatic habitats.

Examples:  Aquatic habitats( water related) - Marine, Fresh water, Estuarine life.

The branches related are: Marine ecology, Estuarine ecology, Limnology, etc

Terrestrial habitats(land based) - life in Forests, Grasslands, Deserts.

The branches related are: Forest ecology, Grassland ecology, etc.

The Synecology includes the study of 1. population characteristics, 2. position of an individual in a population and its relationship (intraspecific), 3. regulation of population, 4. impact of population on the environment, 5. community characteristics and their interrelationships (interspecific), 6. successional changes and 7. the impact of communities over an environment.

AUTECOLOGY

This branch deals with the study of species or the relationship of an organism to one or more environmental conditions. This is also called as species ecology.  It deals with the nutrition, growth, reproduction, development and life history of individual species in an environment.

OTHER BRANCHES OF ECOLOGY

1. Population Ecology : Study of a population, its growth, competition, means of dispersal etc.

2. Community Ecology : Study of distribution of animals in various environments.

3. Ecosystem Ecology : Relation and interaction of plant and animal communities with their total environment. It deals with the formation of soil, chemical cycles, food and feeding relationship, exchange of energy and productivity.

4. Evolution Ecology : Concerned with the manner in which all ecological structure and functions have evolved.

5. Geographical Ecology : Deals with the distribution of organisms over the world and the factors and forces brought out this distribution.

6. Palaeoecology : Deals with the organisms and their environment existed in the distant geological past.

7. Applied Ecology : Deals with wild life management, forest conservation, biological control, animal husbandary and pollution control.

8. Oceanography : Study of marine habitat and organisms.

9. Limnology : Study of life in freshwater bodies.

10. Terrestrial Ecology : This is a major field including a. Forest Ecology, b. Cropland Ecology and c. Grassland Ecology.