The term "Ecology" is derived from the Greek words: Oikos (homee) and logos (the study). According to earnest Haeckel "Ecology is the scientific study of the relationship to their habits and habitats". According to Odum "Ecology is the study of structure and functions of nature and ecosystems". According to Colinvauk, "Ecology is the study of animals and plants in situations to their habits and habitats".
Sub-divisions of ecology:
Ecological studies are made from time to time based on three principal aspects such as - (1) taxonomic affinities (2) based on habitats (3) levels of organization. The taxonomic affinities include - plant ecology which means study of plants with the environment and animal ecology to study the animals with their environments. There are different types of habitats such as fresh water, marine forest etc. and such as habitat approach lead to habitats ecology. In community ecology there is group study belonging to different species - plants as well as animals. In ecosystem ecology there is interaction of biotic A-biotic components. There is interaction to from an integrated system of ecological complex or ecosystem.
Scope of ecology: by the help of ecology we can understand the following idea like:
(1) Species, vegetation, flora: A species is a natural biological unit tied together by the sharing of a common gene pool.
(2) We get knowledge of the sub-divisions of ecology.
(3) Auto-Ecology: It is ecology of individuals by which we can study the relations of individuals to its environment.
(4) Gynecology: Under natural conditions plants, animals, microbes live together as a natural group, known as community. Gynecology deals with population ecology. in population ecology individual study are done. The collective and continuous growth of plants in space is called vegetation.
(5) Population community: A community is a group of population of different species in a given area. They live together.
(6) Environmental habitat: A shows the particular set of environmental conditions suitable for its successful growth.
(7) Adaptations: The organisms to exist under the conditions of its habitats are called adaptations.
(8) Ecological succession: Succession is a natural process by which different groups or communities colonize the same area over a period of time in different sequence.
(9) Ecosystem biosphere: The planet earth along with the atmosphere that sustains life is known as biosphere.
(10) Biochemical cycles: the circular path ways through which the chemical elements circulate in the biosphere are known as biogeochemical cycles.
(11) Food chain, food-web, and productivity: The transfer of energy from the source s in plants through a series of organisms with repeated eating and being eaten is known as food chain. The interlocking of a number of food chain forms a web-like arrangement known as food web.
The rate of production of organic matter accumulated in the living component of an ecosystem in unit time is referred as productivity.