environment and ecology

Environment and Ecology:Important Definition

Environment and Ecology:Important Definition


It is the part of earth which supports life or the domain of living organisms, it comprises the hydrosphere (all seas, lakes and other water bodies), the atmosphere and lithosphere.

It has the following characteristics:

  • The sphere of life and organic activity extends from the ocean floor to about 8 kms (5 miles) in the atmosphere and on land surface to a depth of about 2 kms, where some micro-organisms are found.
  • Any disruption in any of these components can affect the quality of life in the biosphere.
  • The diversity of organisms is a response to the interaction of atmosphere, hydrosphere and lithosphere which produce a variety of conditions within which the biosphere exists.
  • The biosphere includes many ecosystems from simple to complex, each operating within general spatial boundaries.


It refers to function or occupation of a life form within a particular community. It has the following characteristics:

  • It is a phenomenon by which an organism obtains and sustains the physical chemical and biological factors it necessarily requires to survive.
  • An individual species must satisfy several aspects of its niche which are a habitat niche, a trophic (food niche) and a reproductive niche.
  • In a stable community, no niche is left unfilled. The competitive Exclusion Principle states that no two species can occupy the same niche (food or space) successfully in a stable community.
  • Thus, closely related species are separated spatially from one another. In order words, each species operates to reduce competition.


The net photosynthesis for an entire plan community is called its net primary productivity.

It is the amount of stored chemical energy that the community generates for the ecosystem.


It is the net dry weight of organic material, both, above ground and below ground and both, living and dead, such as trees, crops, grasses, tree litter and roots.

It is the biomass that feeds the food chain. It is a measure of life sustaining ability or the productivity of a environment, like a pond, a field or a forest.


It is a process in which oxygen is removed from the water by the decomposition of large amounts of organic matter. Lake Ene, lakes of trophical latitudes, Dal and Wular Lakes in Kashmir, lakes in Hyderabad such as Nizam Sagar, etc., have been adversely affected by this process.


It is a measure of organic pollution in the water bodies. It has the following charcateristics:

  • It is the amount of oxygen required by the aerobic microbes present in the water to break down the organic pollutants.
  • High biological demand means a higher level of pollution.
  • It is also termed as bio-chemical oxygen demand.
  • The amount of dissolved oxygen is measured by milligrams per litre.


It is the mixture of methane and carbon-dioxide generated by action of anaerobic bacteria in animal and human wastes enclosed in a digesting chamber. Animal dung human sewage or crop residue is fermented to produce this gas.


It is a boundary transition zone between adjoining ecosystems and it may vary in width.

It represents an area of tension, as similar species of plants and animals might complete for the resources.


Bio-accumulation has the following features:

  • It is termed as the increase in concentration of a chemical in organisms which reside in contaminated environments.
  • It also describes the progressive enhancement in the amount of a particular chemical in an organism resulting from rates of absorption of a substance in excess of its metabolism and excretion.


It is the capability of ecosystems to produce useful biological materials and to absorb waste material generated.

It has the following characteristics:

  • It is calculated by multiplying the actual physical area by the yield factor and the appropriate equivalence factor.
  • It is expressed in units of global hectares.


It is derived from the ancient Greek word ‘Phyto’ which means plant and Latin word ‘remedium’ which means restoring balance or remediation.

It has the following characteristics:

  • It is the method of treatment of environmental problems (bio-remediation) by the use of plants which can mitigate and environmental issues without the need to excavate the contaminant material and disposing it elsewhere.
  • It is considered a clean, cost-effective and non-disruptive technology, as compared to mechanical cleaning methods.


Phytoremediation refers to the natural ability to some plants known as hyperaccumulators, which bioaccumulate or render harmless contaminants in soil, water and air.

It has the following characteristics:

  • Contaminants such as metals, pesticides and crude oil can be mitigated successfully by phytoremediation projects.
  • Some plant species, such as mustard plants, alpine pennycresses, popular tree and pigweed have been successful at hyper accumulating contaminants at toxic waste sites.


It is a kind of fuel preparation from dry organic matter of combustible oils from plants, for example, alcohol from sugar, black liquor from paper manufacturing process, wood and soybean oil, etc.

Fossil Fuel

It has the following characteristics:

  • It is the fuel such as coal or oil that was formed over millions of years from the remains of animals or plants.
  • Fossil fuel burning generates carbon-dioxide in huge amounts which leads to air pollution.

The concept of carbon credit came into existence as part of an international agreement known as the Kyoto Protocol (1997).

It has the following key points:

  • These credits are certificates issued to countries which reduce their emissions of GHGs (Green House Gases).
  • One credit is equal to one tonne of carbon dioxide emission.


These are the areas of terrestrial and coastal ecosystems and are internationally recognized within the framework of UNESCO’s Man and Biosphere (MAB) programme.

There are 701 biosphere reserves in 124 countries, including 21 transboundary sites. They are distributed as follows:

  • 79 sites in 29 countries in Africa
  • 33 sites in 12 countries in the Arab States.
  • 157 sites in 24 countries in Asia and the Pacific.
  • 302 sites in 38 countries in Europe and North America.
  • 130 sites in 21 countries in Latin America and the Caribbean.

It has the following characteristics:

  • These reserves are required to meet a set of criteria before being inducted to the World Network of Biosphere designated by UNESCO.
  • These reserves are rich in biological and cultural diversity and include unique feature of exceptionally pristine nature.
  • Biosphere reserves are ecosystem-oriented.

The first international Congress convened by UNESCO and UNEP (United Nations Environment Programme) at Minsk Belarus, in co-operation with the Food and Agriculture Organization of the United Nations (FAO) and the World Conservation Union (IUCN). The Congress’s activities gave rise in 1984 to an ‘Action Plan for Biosphere Reserves’ which was formally endorsed by the UNESCO General Conference and by the Governing Council of UNEP, in 1983 and outlined the characteristics of the biosphere reserves.

According to it, each biosphere reserve should consist of:

Core Zone or natural zone

  • In this zone, human activity is completely restricted.
  • It is legally-protected and undisturbed ecosystem.

Buffer zone

  • The immediate surrounding area of core zone is known as the buffer zone. Here, limited human activities such as research, education and research strategies are allowed.

Manipulation zone or the transition zone

  • It is the outermost or peripheral region of biosphere reserve.
  • With the assistance of reserve management and local people, some human activities are carried out without harming the environment.

National Park

It is an area where more than that one ecosystem exists and which has not been physically- altered because of the anthropogenic activities.

It has the following characteristics:

  • Here, species of plants and animals, physiographical regions and natural habitats are protected for scientific research and sight-viewing.
  • Usually, a natural park is oriented towards a particular wild animal.

Wildlife Sanctuary

A wildlife sanctuary is established for the protection of animals and related species. It has the following characteristics:

  • Human activities are allowed in wildlife sanctuaries, whereas in a national park, it is not allowed.
  • Wildlife sanctuaries are usually species-oriented.


The varied range of flora and fauna is called biodiversity. The maintenance of biodiversity is seen to be of critical importance, both in environmental terms and a source for human survival.

It has five major aspects as mentioned below:

  • The distribution of different kinds of ecosystems which include communities of plant and animal species and the surrounding environment and which are valuable not only for the species they contain, but also in their own right.
  • The total number of species in a particular region of area.
  • The number of endemic species in an area.
  • The genetic diversity in individual species.
  • The sub-population of an individual species which embrace the genetic diversity.

Alpha and Beta Bio-Diversity

Alpha bio-diversity represents the number of species in a particular area and Beta bio-diversity is represented by the turnover of species across space.


As defined by the World Commission on Environment and Development (The Brundtland Commission, 1987), sustainable developments is the development that meets the needs of the present generation without compromising the ability of future generation to meet their own needs. The concept of sustainable development has its roots in utilitarian management to get sustained yields from the renewable resources like soil, forest and fisheries.

In Situ and Ex Situ Conservation

In Situ Conservation includes the conservation of plants and animals in the native ecosystems of even in man-made ecosystems, where they naturally occur, whereas, ex-situ conservation includes conservation of samples of genetic diversity, (particularly representing endangered species) away from their habitats.

Bio-Diversity Hotspot

Norman Myers gave the concept of Biodiversity hot spots in 1988 to designate priority areas for in situ conservation.

It has the following characteristics:

  • A bio-diversity hotspot is a bio-geographic region with a significant reservoir of bio-diversity which is under threat from humans.
  • To qualify as a biodiversity hotspot on Myers 2000 edition of the hotspot map, a region must meet two criteria- it must contain at least 0.5% or 1, 500 species of vascular plants as endemic an it should have lost at least 70% of its primary vegetation.
  • Around the world, 36 areas qualify as hotspots. They represents just 2.4% of Earth’s land surface, but they support found no place else- nearly 43% of bird, mammal, reptile and amphibian species as endemics.
  • These sites support nearly 60% of the world’s plant bird, mammal, reptile and amphibian species with a high share of endemic species.

The biodiversity hotspots related to India are:

  1. Western Ghats and Sri Lanka
  2. The Eastern Himalayas
  3. Indo-Burma
  4. Sundaland

Food Chain

It is a chronological pathway which shows the flow of energy from one organism to the other.

It has the following characteristics:

  • In a community which contains producers, consumers and decomposers, the energy flows in a particular pathway.
  • Energy is not created or destroyed; rather it flows from one level to the other, through different organisms.
  • It shows a single pathway from the producers to the consumers and how the energy flow in this pathway.

Food chain in Terrestrial Ecosystem

The sun is the prime source of energy and this energy is used by the producers or plants to prepare their food, by photosynthesis. Next up, in this chain are another organisms which are the consumers and eat this food.

The primary consumers are the organisms that consume the primary producers. In a terrestrial ecosystem, it could be an herbivore, such as cow or goat or a man. But, when a goat is eaten by man, he becomes the secondary consumer.

Example of food chain

Grass (Producer)- Goat (Primary Consumer)- Man (Secondary Consumer) When dead organic matter becomes the starting of a food chain, then it is known as the detritus food chain (DFC)

Food Web

Many inter-connected food chains are called food web. It reflects a real representation of the energy flow through different organism in an ecosystem.


It involves the continuous circulation of water in the earth-atmosphere system. Its main processes are- evaporation, transpiration, condensation, precipitation and runoff.

It has the following characteristics:

  • Although the total amount of water within the cycle remains the same, its distribution among the various processes in changes continuously.
  • The water cycle involves the exchange of energy, which results in temperature variations.
  • When water evaporates, it takes up energy from the surroundings and cools the environment.
  • When it condenses, it releases energy and heats the environment. These heat exchange have significant impact on the climate.

Environment and Ecology:Important Definitions

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