Editorial Articles

volume-9, 1 - 7 June 2019


Shreya Bhattacharya

Environment is defined as the physical surrounding of organisms including human beings of which they are a part and on which they are dependent for their activities like physiological functioning, production and consumption. In other words, everything that surrounds or affects an organism during its life time is collectively known as its environment. It is the source of oxygen, food, habitat, energy, water and other needs for all organisms. It comprises of living (biotic) as well as non-living (abiotic) components.

Abiotic Components

Abiotic environment includes inorganic and non-living parts of the world. This part consists of chemicals like oxygen and nitrogen, soil, water, atmosphere, light and energy. The abiotic environment is made-up of many objects and forces that influence one another and the surrounding community of living things. The weather is an important group of abiotic components. Temperature, evaporation of water, humidity, rain, wind and numerous other weather conditions influence both living and nonliving things on the earth. Physical processes like earthquakes, floods, volcanoes, etc. are also part of abiotic parts.

Biotic components

The word 'biotic' means living. Biotic components are those that have life. They include living organisms including plants, animals, microbes, etc. A biotic factor is any living component that includes a number of interrelated populations of different species in a common environment. A biotic factor can be any organism that affects any other organism including animals that consume other organism and food the organism consumes. Biotic factors in an environment require food and energy to survive. They are further classified as per their functional attributes.

  1. Autotrophs or Producers:

The word 'autotroph' comes from the root words 'auto' for self and 'troph' for food. Thus, autotrophs are those organisms that can produce their own food. They prepare their food using materials from inorganic sources (abiotic components). However, they feed themselves without the assistance of any other organisms. Autotrophs are also called as 'producers'. They form the base of energy pyramid in an ecosystem and provide food tat all the heterotrophs need to exist.

Types of Autotrophs:

Autotrophs are classifieds according to the way they obtain their energy: a) Photoautotrophs, and b) Chemoautotrophs.

  1. a) Photoautotrophs: These organisms get the energy from sunlight to make organic materials. This set of organisms perform a process called photosynthesis in which photons from the Sun are captured and used to perform food. Photoautotrophs include plants, green algaes, and bacteria. They make organic compounds and fuels that give support to heterotrophs including human beings. During the process of photosynthesis, these organisms take carbon from the atmosphere, mainly from CO2, and use it to make sugars and other molecules that store the Sun's energy in their molecular bonds. This process releases molecules of oxygen that is vital for our survival. It is believed that free oxygen was not present in Earth's atmosphere until after photoautotrophs became common in Earth's seas. The release of large amounts of free oxygen into Earth's atmosphere by photoautotrophs paved the way for large animals, like ourselves. Photoautotrophs are also credited for the Earth's Ozone layer as some of the oxygen produced by them created the ozone layer, which protects life on the planet from the Sun's UV light.
  2. b) Chemoautotrophs: These are the organisms that obtain energy from inorganic chemical processes. They use volatile chemicals such as molecular hydrogen, hydrogen sulfide, elemental sulfur, ferrous iron, and ammonia as their energy sources. They are most commonly found in deep water environments which receive no sunlight. They are usually bacteria or archaebacteria as their metabolisms are usually not efficient enough to support multicellularity.
  3. Heterotrops or phagotrophs:

Heterotrophs consists of two words, hetero meaning other and troph for food. Heterotrophs are organisms that obtain their energy by feeding on others (or on organic compounds). These organisms cannot make their own food, so they must eat or absorb it. They depend on organic food derived from autotrophs or other heterotrophs. Heterotrophs are also known as consumers.Any heterotrophic organism that feeds by ingesting organisms or organic particles, which are digested within its body is knows as phagotroph (macroconsumer). Herbivores are primary consumers which feed mainly on plants, e.g. deer, cow; whereas, secondary consumers or Carnivores feed on primary consumers, e.g. wolves. There is another set of heterotrophs that consume both plants and animals and is termed as Omnivores. Human Beings fall in this category. Besides macroconsumers or phagotrophs, there are organisms that survive on dead organic substances or detritus of plants and animals. They are mostly decomposers and are called Saprotrophs. They are microconsumers. Earthworms and other soil organisms like millipedes and woodlice are called detrivores and they play an important role in the cycling of nutrients and are an essential part of most biogeochemical cycles, such as the carbon cycle, nitrogen cycle and the phosphorous cycle.

After knowing the abiotic and biotic components of environment, we should now discuss another important concept and that is Ecology.


Ecology is the scientific study of the relations that living organisms have with respect to each other and their natural/physical environment.It deals with the ways in which organisms are shaped by their environment, how they make use of environmental resources. It helps us understand how the world works. It provides useful evidence on the interdependence between people and the natural world and, as well the consequences of human activity on the environment. There are seven specific levels in the ecology that exist, sometimes discretely and sometimes with overlap. These levels are organism, population, community, ecosystem, biome and biosphere.At each level, these units have a specific structure and function.


They make the basic unit of study in ecology. Organisms are living beings that have the ability to act or function independently, e.g. plant, animal, etc. The organisms of the similar type have the potential for interbreeding, and produce fertile offspring, which are called species.An organism is fully adapted to its environment.


A population is a group of individuals of the same species, inhabiting a geographical area, and functioning as a unit of biotic community.A population's geographic range has limits, or bounds, established by the physical limits that the species can tolerate, such as temperature or aridity, and by the encroachment of other species. Population density is the relation between the number of individuals of a population and the area they occupy.


A community is the set of all populations that inhabit a certain area.  It is not a rigid or fixed structure. Communities can have different sizes and boundaries. These are often identified with some difficulty.For example, a forest of trees and undergrowth plants, inhabited by animals and rooted in soil containing bacteria and fungi, constitutes a community.


Ecosystem is  a community of plants and animals interacting with each other in a given area, and also with their non-living environments.An ecosystem is a complex set of relationship among the living resources, habitats and residents of an area. It includes plants, trees, animals, fish, birds, micro-organism, water, soil and people. Ecosystem vary greatly in size and elements that make them but each is a functioning unit of nature. Everything that lives in an ecosystem is dependent on the other species and elements that are also part of that ecological community. If one part of an ecosystem is damaged or disappears, it has an impact on everything else.There are essentially two kinds of ecosystems; Aquatic and Terrestrial. These two can be further divided into various sub-categories like desert ecosystem, forest ecosystem, grassland ecosystem, mountain ecosystem, marine ecosystem, freshwater ecosystem.


A Biome is a large ecological area on the earth's surface, with flora (plants)and fauna (animals) adapting to their environment. Biomes are often defined by abiotic factors such as temperature, climate, relief, geology, soils and vegetation. A biome,in a way, may look like a massive ecosystem but they are not. A biome may be home to many units of ecosystems. There are some major categories of biomes on earth.


The term biosphere is derived from two greek words, bios meaning life and sphaira meaning sphere is the layer of the planet Earth where life exists. This layer ranges from heights of up to ten kilometres above sea levelto depths of the ocean. The biosphere is one of the four layers that surround the Earth along with the lithosphere (rock), hydrosphere (water) and atmosphere (air) and it is the sum of all the ecosystems.The biosphere is unique. So far there has been no existence of life elsewhere in the universe. Life on Earth depends on the sun. Energy, provided as sun light, is captured by plants, some bacteria and protists, in the marvellous phenomenon of photosynthesis. The captured energy transforms carbon dioxide into organic compounds such as sugars and produces oxygen. The vast majority of species of animals, fungi, parasitic plants and many bacteria depend directly or indirectly on photosynthesis.

While discussing Biosphere, it is important to discuss Biosphere Reserves.

Biosphere Reserve

Biosphere reserves is an area of terrestrial or coastal ecosystems promoting solutions to reconcile the conservation of biodiversity with its sustainable use. They are internationally recognized, nominated by national governments and remain under sovereign jurisdiction of the states where they are located. In 1968, UNESCO organized the Biosphere Conference, which saw the beginning of the concept of a "Biosphere Reserve". This was the first intergovernmental conference examining how to reconcile conservation and use of natural resources, thus foreshadowing the present-day notion of sustainable development. This conference resulted in the launching of the Man and the Biosphere Programme in 1970. One of the original MAB projects consisted in establishing a coordinated World Network of sites representing the main ecosystems of the planet in which genetic resources would be protected, and where research on ecosystems as well as monitoring and training work could be carried out. These sites were named as "Biosphere Reserves". These are large areas of bio diversity where flora and fauna are protected. These regions of environmental protection roughly correspond to IUCN Category V Protected areas. Biosphere reserves have three interrelated zones that aim to fulfil three complementary and mutually reinforcing functions:

  1. a) The core area(s) comprises a strictly protected ecosystem that contributes to the conservation of landscapes, ecosystems, species and genetic variation.
  2. b) The buffer zone surrounds or adjoins the core areas, and is used for activities compatible with sound ecological practices that can reinforce scientific research, monitoring, training and education.
  3. c) The transition area is the part of the reserve where the greatest activity is allowed, fostering economic and human development that is socio-culturally and ecologically sustainable.

There are 686 biosphere reserves in 122  countries, including 20 transboundary sites. In India, the government has established 18 Biosphere Reserves to protect larger areas of natural habitat. List of Biosphere Reserves, their area, date of designation, and location


Name of the Biosphere Reserve & total geographical area (Km2)

Date of Design-action

Location in the State(s)/Union Territory


Nilgiri (5520)


Part of Wynad, Nagarhole, Bandipur and Madumalai, Nilambur, Silent Valley and Siruvanihillsin Tamil Nadu, Kerala and Karnataka.


Nanda Devi (5860.69)


Part of Chamoli, Pithoragarh and Almora districts in Uttarakhand.


Nokrek (820)


Part of East, West and South Garo Hill districts in Meghalaya.


Manas (2837) Part of


Part of Kokrajhar, Bongaigaon, Barpeta, Nalbari, Kamprup and Darang districts in Assam.


Sunderban (9630)


Part of delta of Ganges & Brahamaputra river system in West Bengal


Gulf of Mannar (10500)


India part of Gulf of Mannar extending from Rameswaramisland in the North to Kanyakumari in the South of Tamil Nadu


 Great Nicobar (885)


Southern most island of Andaman and (885) Nicobar Islands.


Similipal (4374)


Part of Mayurbhanj district in Orissa


Dibru-Saikhova (765)


Part of Dibrugarh and Tinsukia districts in Assam


Dehang-Dibang (5111.5)


Part of Upper Siang, West Siang and Dibang Valley districts in Arunachal Pradesh.


Pachmarhi (4981.72)


Part of Betul, Hoshangabad and Chhindwara districts in Madhya Pradesh.


Khangchendzonga (2931.12)


Part of North and West districts in Sikkim.


Agasthyamalai (3500.36)


Part of Thirunelveli and Kanyakumari districts in Tamil Nadu and Thiruvanthapuram, Kollam and Pathanmthitta districts in Kerala.


Achanakmar- Amarkantak (3,835.51)


Part of Anuppur and Dindori districts of   Amarkantak Madhya Pradesh and Bilaspur district of Chattisgarh.


Kachchh (12,454)


Part of Kachchh, Rajkot, Surendranagar and Patan districts in Gujarat.


Cold Desert (7,770)


Pin Valley National  Park  and surroundings; Chandratal & Sarchu; and Kibber Wild life sanctuary in Himachal Pradesh


Seshachalam (4755.997)


Seshachalam hill ranges in Eastern  Ghatsen compassing part of Chittoor


Panna (2998.98)


Part of Panna and Chhattarpur districts in Madhya Pradesh


(Source: www.moef.gov.in)

*The author is a Mumbai based journalist. Her email is shreyabh.journo@ gmail.com

 Views expressed are personal.

 (Image Courtesy : Google)