Definition of ecology:

• Ecology deals with the inter-relationship between biotic and abiotic components as well as the relationships among the individuals of the biotic components. (Cited from Shukla and Chandel, 1996)
• Ecology is a science of ecosystems or totality of reciprocal interactions between luring, organisms and their physical surroundings. (ME Clark, 1973)
• Ecology is the study of the reciprocal relationship between living organisms and their environments. Ernest Haeckel (1866)
• Ecology is the study of the structure and the function of nature (Odum).

Divisions of Ecology:

• Ecology is divided into two major divisions: autoecology and synecology.

A) Autoecology: Autoecology is the ecological study of individual species of plant and its environment or is the ecological study of individual animal or plant species or its population thought its life history in relation to the habitat in which it grows.

B) Synecology : Synecology is the ecological study of community of plants in the environment.

• When synecology of both plants and animals are considered together, it is called bio-synecology or bio-sociology.
• The study of the distribution and migration of plants in earth is called ptytogeography.

Different fields of Ecology

1. Habitat Ecology. Forest ecology, Grassland ecology, Fresh water ecology (Limnology), Wetland ecology, Terrestrial ecology, Rural ecology, Urban ecology, Global ecology, Marine ecology, Desert ecology, Mountain ecology, Space ecology.

2. Paleoecology
3. Radiation ecology
4. Cytoecology, Genecology
5. Ecosystem ecology
6. Conservation ecology/Resource ecology
7. Ecological energetic and production ecology. Mechanism and quantity energy conversion and flow of energy through organism, Energy production process, rate of increase in organism  weights of organism in relation to species in ueran.

8. Taxonomic group: Weed ecology, Insect ecology, Agroecology, Microbial ecology
9. Ethnoecology. Traditional knowledge of plant phonology, adaptations and implaitous with other organisms. Nature and environmental vegetation management.

10. Ethology: animal behavior with relation to its environment.