Components of Environment
Components of Environments: All organisms are intimately dependent on the environment from which they derive their sustenance. Organisms from virus to man are obligatorily dependent on the environment for food, energy, oxygen, shelter and for other needs.
The environment is defined as ‘the sum total of living, non-living components; influences and events, surrounding an organism’. The relationship and interaction between organism and environment are highly complex.
For the convenience of study, environment is broadly classified into two components:
1) A biotic and 2) Biotic.
1) A biotic Components: Energy, Radiation, Temperature & heat flow, Water, Atmospheric gases and wind, Fire, Gravity, Topography, Geologic substratum, soil.
2) Biotic Components: Green plants, Non-green plants, Decomposers, Parasites, Symbionts, Animals, Man.
You should realize that the environment is not static. The biotic and a biotic factor are in a flux and keep charging continuously. The organisms can tolerate changes in environment within certain range called ‘range of tolerance’.
External and Internal Environment
Let us try to understand the concept of environment with some examples.
Its environment consists of biotic components such as light, temperature, water in which nutrients, oxygen, other gases and organic matter are dissolved. The biotic environment consists of microscopic plankton as well as higher plants and animals and decomposers. The plants are different kinds such as phytoplankton, partly submerged plants and plants and trees growing around the edge of the pond. The animals consist of zooplankton, insects, worms, mollusks, tadpoles, frogs, birds and various kinds of fishes. The decomposers are the saprotrophs.
The environment of the fish described above is its external environment. Living organisms also possess an internal environment, enclosed by the outer body surface. The body surface acts as an exchange barrier between the external environments.
The internal environment is relatively stable as compared to the external environment. However, it is not absolutely constant. Injury, illness or excessive stress upsets the internal environment .For example, if a marine fish a transferred to a fresh water environment; it will not be able to survive.
Natural versus Artificial Environment
The environment discussed so far are, natural environments. In several instances man has greatly altered the natural conditions and created new situations known as artificial or man-made environments. Examples of artificial environment are cultivated fields or cities. Let us see the difference between the natural and artificial environment by considering the city environment.
The city environment is product of man’s own design. The atmosphere of the city is generally polluted due to the emission of various gases from factories, motor vehicles and electric power plants. Water is obtained not from streams directly but after it has been filtered and disinfected in a water treatment plant. The metabolic wastes and garbage are not disposed of locally but have to be carried through sewer lines for treatment or for dumping in a remote place far away from the city. No food is grown in the city but is imported from rural areas for the city dwellers.
In a city people live in buildings made of bricks, stones and cement. Houses and offices of well off people are air-conditioned creating an atmosphere which remains free from the influence of outside environment. Furthermore, to make life comfortable modern amenities like fans, fridge, radio, television etc. are installed, requiring electricity which is generated by man artificially.
The man-made city environment consumes excessive amounts of energy and materials and needs constant care.
Attributes of Population
You must be familiar with the term ‘population’. It is one of the most talked about issues of this century. It is feared that the rapid growth of the world population if allowed to continue, might outstrip the food supply in the near future. The present high rate of population growth is a major concern of the governments, scientists and administrators.
In a technical sense ‘population’ is defined as a group of freely interbreeding individuals of the same species present in a specific area at a given time. For example, when we say that the population of a city is 50, 000, we mean that there are 50,000 individuals of Homo sapiens in that town. Other living organisms, for example cats and dogs present in the city are not included as they are populations of two different species.
In nature, population of a species is subdivided into a number of local breeding populations called dame. Demes are geographically separated populations of the same species. For example, the garden lizards of Qutub Miner, Delhi, form are separate dame from the garden lizard of Lodi Gardens, Delhi or the garden lizards of Swaraj Bhawan, Allahabad.
Consequently, in a deem each individual has an equal opportunity of mating with another individual of the opposite sex, but not with individuals in another dame. Because of frequent mating and similar environmental conditions members of a dame resemble each other more closely.
A population exhibits certain characteristics which can only be expressed at the population level and not shared by the individuals of the population. For example, individual organisms are born, grow and die but characteristics such as birth rate, death rate, density are only meaningful at the population level.
The attributes of a population are of two basic types: i) Numerical attributes such as density, nasality, mortality, dispersal and ii) structural attributes like age distribution, dispersion and growth form. Some of the basic attributes of population are briefly described below.
- Numerical attributes:
Density: number of individuals per unit area.
Natality: the rate at which new individuals are added to a population through reproduction.
Mortality: the rate at which individuals are lost from a population by death.
Dispersal: the rate at which individuals of a population emigrate from an area.
- Structural attributes:
Population growth form: refers to the pattern of population growth. There are two basis patterns of population growth represented by “J” and “S” shaped growth curves.
Dispersion: the pattern of distribution of individuals in space.
Age distribution: the proportion of individuals of different age group in a population.
The main attributes studied is the density of the population which depends on four parameters: i) Natality, ii) mortality, iii) immigration and, iv) emigration.
Thus whenever the density of a population falls or rises, we try to find out which of the four parameters have changed.
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