In this article, we will discuss about the various branches of ecology and levels of ecological organisation (ecological hierarchy)
Branches of Ecology:
On the basis of study of organism individually or in group, ecology may be sub-divided into following types:
It involves the study of an individual animal or plant throughout its life in relation to the habitat factors. For autecological studies one must have the knowledge of nutrition, growth, reproduction and development of that individual.
If composition and behaviour of plant communities and their relationship to the environment are studied, the subject is called synecology. Synecology is often further subdivided into aquatic and terrestrial ecology.
(i) The aquatic ecology includes fresh water ecology, estuarine ecology and marine ecology.
(ii) Terrestrial ecology, subdivided further into areas such as forest ecology, grassland ecology, cropland ecology and desert ecology, is concerned with terrestrial (land) ecosystems — their microclimate, soil chemistry, nutrient, hydrological cycle and productivity.
Levels of Ecological Organisation (Ecological Hierarchy):
Ecology is basically concerned with various levels of biological organisation – organisms, populations, communities, ecosystems and biomes.
The hierarchy in the levels of organisation connected with ecological grouping of organisms is called ecological hierarchy or ecological levels of organisation.
(i) Individual (Organism) is distinct living entity or distinct package which carries out all life processes in its body, separate from those in other individuals.
Individual organism is the basic unit of ecological hierarchy as it continuously exchanges materials and information with its environment.
(ii) Population is a group of individuals of the same species living together in a common area at a particular time.
Organisms of the same kind may form several populations inhabiting different geographical areas:
1. The different populations of the same kind of organisms are often referred to as local population.
2. Members of a local population may be genetically adapted to their specific environment, such a population is called ecotype.
3. In a given geographical area, a population is further divisible into sub-groups called demes.
4. The interactions between individuals of the same species are more in the members of same deme than between members of different demes.
(iii) Biotic Community is an assemblage of population of different species of plants, animals, bacteria and fungi which live in a particular area and interact with one another through competition, predation, mutualism etc.
(iv) Ecosystem is a segment of nature consisting of a biological community and its physical environment both interacting and exchanging materials as well as energy.
(v) Landscape is a unit of land distinguished by a natural boundary and having patches of different ecosystems.
(vi) Biome is a large regional unit delimited by a specific climatic zone, having a particular major vegetation zone and its associated fauna, e.g., tundra desert, temperate deciduous forest, tropical rain forest, ocean.
(vii) Biosphere is biologically inhabited part of earth along with its physical environment consisting of lower atmosphere, land and water bodies.