The word ecology comes from the Greek Oikos, meaning “household” or “home” or “place of live”. Thus ecology deals with the organism and its place to live. Basically this is the organism’s environment slid so ecology might well be called environmental biology. For one thing the environment includes the surroundings of the animal, and the surroundings can be modified by the animal or plant itself. The environment also includes for the individual organism those of its own kind, as well as organisms of other kinds. There are relationships between individuals within a population and with individuals of different populations. Animals, react in a social sort of way, involving various patterns of behavior. Since all organisms have become adapted to the environment and are always adjusted to the changing environment natural selection and evolution become a part of ecology.
Ecology involves a reciprocal relationship between an organism and s environment. If we consider a pine tree in its natural forest setting, we see that the pine is subjected to environmental influences such as soil water, Wind, soil minerals, the amount of solid oxygen, atmospheric carbon dioxide, the amount of sunlight, the prevailing temperatures, and many other a biotic, or non-living, factors. In addition, there are the biotic, or living, elements of the environment such as bark beetles, birds, squirrels, soil bacteria and fungi, worms and parasites of various types, all of which may be directly or indirectly affect the tree.
The tree, in turn, will modify the surrounding Environment : the shade produced will alter temperatures; its limbs will prevent the free flow of air; transpiration, or water loss, from leaf surfaces will alter the humidity of the air; its root will penetrate the soil, opening up soil channels; and root hairs will extract water from solid spaces, so that the entire soil environment will be modified. We have used a plant to illustrate reciprocal activity. An animal will also exert an influence on the surrounding environment by grazing, predation, burrowing, trampling vegetation and so On. Even the non-living (abiotic) factors of the environment can cause mild or severe changes in an area as evidenced by continuous or abundant precipitation (floods), wind action hurricanes, tornados, typhoons), and gravitational activity (earthquakes, landslides) and so many other factors.
Scope of Ecology : Human being is a part of ecosystem as any other animal. Man has to face many ecological problems like production of grains, livestock, timber, control of pest species, conservation of wildlife etc. Ecology plays very important role in agriculture. Many problems related to agriculture, e.g. management of grasslands, forestry, wood control, crop rotation and biological surveys can be solved using basic concepts of ecology. Other related problems which a man has to face, can be solved through the assistance of trained ecologists. These problems are of varied nature, e.g., pollution, disposal of wastes, deterioration of habitat, knowledge of use of insecticides and fertilizers. Ecologists can also assist in town planning, public health and construction sites for industries. According to Taylor (1936), “Ecology is the sciences of all the relations of all living organisms to all their environment”
Significance of Ecology : It is an important branch of science which helps in understanding the following events:
(1) Interrelationship between living organisms and the environment.
(2) Geographical distribution of organisms.
(3) Interrelationship of populations and community of organisms.
(4) Interrelationship of evolutionary development.
(5) Structural and functional adaptations and ageing of organisms with their physical environment and communities.
(6) Better use of biological productivity of nature for human welfare.
(7) For population control.
(8) Environmental pollution and its control.
From the functional point of view each ecosystem has two main Component
1.Abiotic Component: It consists of nonliving environment which control biotic component. It can be divided into three parts from its structural point of view.
(a) Climatic or physical factors : In physical factors, various environment factors like water, temperature, air, light, rainfall, humidity, energy etc. are included. Number of producers and Consumers in a ecosystem are decided by the environmental factors of the ecosystem and it also decides circulation of nutrients in the system. Energy is transferred by green plants, which are consumed by heterotrophs. Solar energy is Converted into bioenergy by the green plants hence they are referred as autotrophs Amount of abiotic substances in any ecosystem can be referred as standing stage.
(b) Inorganic substance : They comprise essential minerals, for example calcium (Ca), potassium (K), magnesium (Mg), sulphur (S), phosphorus (P) and gases like nitrogen (N2) carbon-dioxide (C02) and Oxygen.
They are taken up by autotrophs producers (green plants) as a raw material and Converted into nutrients. These also participate activity in biogeochemical cycles. These substances are active in both abiotic and biotic components. Initially autotrophs use them and then they reach to heterotrophs through autotrophs. At the time of death of producers or consumers these substances return back into the environment.
(c) Organic Substance : They comprise proteins. Sugar, fats, amino acids etc. Which are synthesized by biotic components of ecosystem and released as wastes or dead remains in the ecosystem. They again enter into the living system through the soil.
2. Biotic components : The living components of the biosphere are called biotic components. The living components of the biosphere are (i) Producers, (ii) Consumers and (iii) Decomposers depending upon their mode of nutrition.
(I) Producers or Autotrophs : Green plants are called producers because they are able to synthesize their food in the presence of sun light and chlorophyll by taking carbon dioxide from the atmosphere and water from the soil. They are also called as autotrophs as they synthesize their own food. As green plants can convert solar energy into chemical energy of food. So according to E.J.Koromondy they can also be called converter.
(II) Consumers or Heterotrophs : Consumers or heterotrophs are
animals which eat food stuffs manufactured by green Consumers are of three types —
1. Primary Consumers: All the herbivores which feed on producers n plants) are called primary consumers. Some common examples of ary consumers are insects, goats, cows, rabbits, grass Shoppers, deer, rots etc.
- Secondary Consumers : The carnivores eat the herbivores or primary consumers and are called secondary consumers. Some common examples of secondary consumers are snakes, frogs, foxes, lizards etc. They are also primary carnivores.
- Tertiary Consumers : They are also called secondary carnivores. carnivores eat the secondary consumers and are called as tertiary consumers. Lions and tigers are common examples of tertiary consumers.
Omnivore: An animal which can eat plants as well as flesh of other animals is called omnivore. Man is omnivore.
(iii) Decomposers or Micro consumers or osmotrophs or protrophs : These are the microorganisms which feed on dead bodies of plants and animals and break down complex organic substance into simpler inorganic substances.