Shankar Ias Environment Part 1-4 Exam time Synopsis 2020


Shankar Ias Environment:

Serial No.



Functions of an Ecosystem
Terrestrial Ecosystem 
Aquatic Ecosystem
Environment Pollution
Renewable Energy
Environmental Issues
Environment Impact Assessment


Indian Biodiversity
Schedule Animals of WPA, 1972
Animal Diversity of India
Plant Diversity of India
Marine organisms
Protected Area Network
Conservation Efforts


Climate Change
Ocean Acidification
Ozone Depletion
Impact of Climate Change
Mitigation Strategies
India and Climate Change
Climate Change Organizations


Acts and Policies
Institution and Measures
Environmental Organizations
International Environmental Conventions
Environmental Issues and Health Effects

Ecology: Shankar Ias Environment


  • Defined as “ascientificstudyoftherelationshipofthelivingorganismswitheachotherand with their environment”.
  • The classical texts of the Vedic period such as the Vedas, the Samhitas, the Brahmanas and the Aranyakas-Upanishadscontainmanyreferencestoecologicalconcepts
  • The Indian treatise on medicine, the Caraka- Samhita and the surgical text Susruta-Samhitacontainclassification of animals on the basis of habit and habitat, land in terms of nature of soil, climate and vegetation; and description of plants typical to various localities.
  • Caraka-Samhitacontainsinformationwhereair, land,waterandseasonswereindispensable for life and that polluted air and water were injurious for health.
  • The environment is defined as “the sum total of living, non-living components; influences and events, surrounding an organism”.
Components of Environment 1. Abiotic – Energy, Radiation, Temperature, Water, etc.2. Biotic- plants, animals, man, Decomposer, etc.
L levels  of Organisation of Ecology Six main levels of organisation of ecology are: Shankar Ias Environment

  1. Individual- Organism is an individual living being that has the ability to act or function independently.
  2. Population-Population is a group of organisms usually of the same species, occupying a defined area during a specific time,
  3. Community- Communities in most instances are named after the dominant plant form (species). A community is not fixed or rigid; communities may be large or small.
  4. The ecosystem-An ecosystem is defined as a structural and functional unit of biosphere consisting of a community of living beings and the physical environment, both interacting and exchanging materials between them.
  • It includes plants, trees, animals, fish, birds, micro-organisms, water, soil, and people.
  • When an ecosystem is healthy (i.e. sustainable) it means that all the elements live in balance and are capable of reproducing themselves
      Types of Community- On the basis of size and degree of relative independence, communities may be divided into two types- Shankar Ias Environment

  1. Major Community

  • These are large-sized, well organised and relatively independent. They depend only on the sun’s energy from outside and are independent of the inputs and outputs from adjacent communities. ExampleTropical evergreen forest in the North-East
  1. MinorCommunities

  • These are dependent on neighbouring communities and are often called societies. They are secondary aggregations within a major community and are not therefore completely independent units as far as energy and nutrient dynamics are concerned. Example A mat of lichen on a cow dung pad.
  • The environmental factors determine the characteristic of the community as well as the pattern of organisation of the members in the community
  • The characteristic pattern of the community is termed as a structure which is reflected in the roles played by various population, their range, the type of area they inhabit, the diversity of species in the community and the spectrum of interactions between them.
Components of Ecosystem
  • The components of the ecosystem is categorised into abiotic or non-living and biotic or living components. 
  • Both the components of the ecosystem and environment are the same.
1. Abiotic Components
  • The inorganic and non-living parts of the world.
  • Consists of soil, water, air, and light energy etc.
  • Involves a large number of chemicals like oxygen, nitrogen-, etc. and physical processes including volcanoes, earthquakes, floods, forest fires, climates, and weather conditions.
  • Abiotic factors are the most important determinants of where and how well an organism exists in its environment. Although these factors interact with each other, one single factor can-limit the range of an organism.
  1. Energy

  • Energy from the sun is essential for the maintenance of life. Energy determines the distribution of organisms in the environment.
  1. Rainfall

  2. Temperature

  • Temperature is a critical factor of the environment which greatly influences the survival of organisms. 
  • Organisms can tolerate only a certain range of temperature and humidity.
  1. Atmosphere

  • It is made up of 21% oxygen, 78% nitrogen, 0.038% carbon dioxide and other inert gases (0.93% Argon, Neon etc).
  1. Substratum

  • The land is covered by soil and a wide variety of microbes, protozoa, fungi and small animals (invertebrates) thrive in it
  1. Materials: Organic compound

Such as proteins, carbohydrates, lipids, humic substances are formed from the inorganic compound on decomposition.

  1. Inorganic compound

  • Such as carbon, carbon dioxide, water, sulphur, nitrates, phosphates, and ions of various metals are essential for organisms to survive.
  1. Latitude and altitude

  • Latitude has a strong influence on an area’s temperature, resulting in a change of climates such as polar, tropical, and temperate. These climates determine different natural biomes.
  • From sea level to the highest peaks, wildlife is influenced by altitude. As the altitude increases, the air becomes colder and drier, affecting wildlife accordingly.(wildlife decrease as altitude increase)
2. Biotic Components
  • Biotic components include living organisms comprising plants, animals and microbes and are classified according to their functional attributes into producers and consumers.
  • Primary producers – Autotrophs (self-nourishing)  Primary producers are basically green plants (and certain bacteria and algae). They synthesise carbohydrate from simple inorganic raw materials like carbon dioxide and water in the presence of sunlight by the process of photosynthesis for themselves and supply indirectly to other non- producers.
  • In the terrestrial ecosystem, producers are basically herbaceous and woody plants, while in aquatic ecosystem producers are various species of microscopic algae.
  1. ConsumersHeterotrophs or phototrophs (other nourishing)
  • Consumers are incapable of producing their own food (photosynthesis).
  • They depend on organic food derived from plants, animals or both.
  • Consumers can be divided into two broad groups
  1. Macro consumers- They feed on plants or animals or both and are categorised on the basis of their food sources.
  • Herbivores are primary consumers which feed mainly on plants e.g. cow, rabbit.
  • Secondary consumers feed on primary consumers e.g. wolves.
  • Carnivores which feed on secondary consumers are called tertiary consumers e.g. lions which can eat wolves.
  • Omnivores are organisms which consume both plants and animals e.g. man.
  1. Micro consumersSaprotrophs (decomposers orosmotrophs)
  • They are bacteria and fungi which obtain energy and nutrients by decomposing dead organic substances (detritus) of plant and animal origin.
  • The products of decomposition such as inorganic nutrients which are released in the ecosystem are reused by producers and thus recycled.
  • Earthworm and certain soil organisms (such as nematodes, and arthropods) are detritus feeders and help in the decomposition of organic matter and are called detrivores.

Classification of Eco-system

  • Natural Ecosystem- Shankar Ias Environment

  • TerrestrialForests, Grasslands, Deserts
  • Aquatic- Fresh Waters, Saline Waters, Marine Waters
  • A zone of the junction between two or more diverse ecosystems. For e.g. the mangrove forests represent an ecotone between marine and terrestrial ecosystem.

Characteristics of Ecotone

  • It may be very narrow or quite wide. It has the conditions intermediate to the adjacent ecosystems. Hence it is a zone of tension.
  • It is linear as it shows a progressive increase in species composition of one incoming community and a simultaneous decrease in species of the other outgoing adjoining community.
  • Well developed ecotones contain some organisms which are entirely different from that of the adjoining communities.
  • Sometimes the number of species and the population density of some of the species is much greater in this zone than either community. This is called Edge effect. For example, the density of birds is greater in the mixed habitat of the ecotone between the forest and the desert.
  • A description of all the biological, physical and chemical factors that a species needs to survive, stay healthy and reproduce.
  • No two species have exact identical niches. Niche plays an important role in the conservation of organisms.

Types of Niche

  1. Habitat niche where it lives
  1. Food niche what is eats or decomposes&what species it competes with
  1. Reproductive nichehow and when it reproduces.
  1. Physical & chemical niche temperature, land shape, land slope, humidity & another requirement.
  • The terrestrial part of the biosphere is divisible into enormous regions called biomes, which are characterised by climate, vegetation, animal life and general soil type.
  • No two biomes are alike.
  • The most important climatic factors are temperature and precipitation.
  1. Tundra- Northernmost region adjoining the ice-bound poles.
  • Devoid of trees except for stunted shrubs in the southern part of tundra biome, ground flora includes lichen, mosses and sedges.
  • The typical animals are reindeer, arctic fox polar bear, snowy owl, lemming, arctic hare, ptarmigan. Reptiles and amphibians are almost absent
  1. Taiga- Northern Europe, Asia and North America. Moderate temperature than tundra. Also known as boreal forest.
  • The dominating vegetation is coniferous evergreen mostly spruce, with some pine and firs.
  • The fauna consists of small seed-eating birds, hawks, fur-bearing carnivores, little mink, elks, puma, Siberian tiger, wolverine, wolves etc.
  1. Temperate Deciduous Forest- Extends over Central and Southern Europe, Eastern North America, Western China, Japan, New Zealand etc.
  • Moderate average temperature and abundant rainfall. These are generally the most productive agricultural areas of the earth
  • The flora includes trees like beech, oak, maple and cherry.
  • Most animals are familiar with vertebrates and invertebrates.
  1. Tropical rain forest- tropical areas in the equatorial regions, which abound with life. Temperature and rainfall high.
  • Tropical rainforest covers about 7% of the earth’s surface & 40% of the world’s plant and animal species.
  • Multiple storeys of broad-leafed evergreen tree species are in abundance.
  • Most animals and epiphytic plants(An epiphyte is a plant that grows harmlessly upon another plant) are concentrated in the canopy or treetop zones
  1. Savannah- Tropical region: Savannah is most extensive in Africa
  • Grasses with scattered trees and fire-resisting thorny shrubs.
  • The fauna includes a great diversity of grazers and browsers such as antelopes, buffaloes, zebras, elephants and rhinoceros;
  • the carnivores include lion, cheetah, hyena; and mongoose, and many rodents
  1. Grassland- North America, Ukraine, etc. Dominated by grasses. Temperate conditions with rather low rainfall. Grasses dominate the vegetation. The 
  2. fauna include large herbivores like bison, antelope, cattle, rodents, prairie dog, wolves, and a rich and diverse array of ground-nesting bird
  3. Desert- Continental interiors with very low and sporadic rainfall with low humidity.

Aquatic Zones

  • Aquatic systems are not called biomes,
  • The major differences between the various aquatic zones are due to salinity, levels of dissolved nutrients; water temperature, depth of sunlight penetration.
    1. Fresh Water Ecosystem-Fresh water ecosystem are classified as lotic (moving water) or lentic (still or stagnant water).
  • Marine Ecosystem: Shankar Ias Environment
  1. Estuaries-Coastal bays, river mouths and tidal marshes from the estuaries.
  • In estuaries, fresh water from rivers meet ocean water and the two are mixed by the action of tides.
  • Estuaries are highly-productive as compared to the adjacent river or sea


  • A part of the earth where life can exist.
  • represents a highly integrated and interacting zone comprising of the atmosphere (air), hydrosphere (water) and lithosphere (land)
  • Life in the biosphere is abundant between 200 metres (660 feet) below the surface of the ocean and about 6,000 metres (20,000 feet) above sea level.
  • Absent at extremes of the North and South poles.
  • Living organisms are not uniformly distributed throughout the biosphere

Functions of an Ecosystem

  • ENERGY FLOW Energy is the basic force responsible for all metabolic activities.
  • The flow of energy from producer to top consumers is called energy flow which is unidirectional.
  • Energy flows through the trophic levels: from producers to subsequent trophic levels.
  • There is a loss of some energy in the form of unusable heat at each trophic level.

Types of Trophic level interaction

The trophic level interaction involves three concepts namely:- Shankar Ias Environment

    1. FoodChain
    2. FoodWeb
    3. Ecological Pyramids
  1. FOOD CHAINA food chain starts with producers and ends with top carnivores. The sequence of eaten and being eaten produces a transfer of food, energy and it is known as a food chain.
  • Grazing food chainThe consumers who start the food chain, utilising the plant or plant part as their food, constitute the grazing food chain.
  • This food chain begins from green plants at the base and the primary consumer is a herbivore
  • For example, in a terrestrial ecosystem, the grass is eaten up by caterpillar, which is eaten by lizard and lizard is eaten by a snake.
  • In aquatic ecosystem phytoplankton (primary producers) is eaten by zooplanktons which is eaten by fishes and fishes are eaten by pelicans
  • Detritus food chain The food chain starts from dead organic matter of decaying animals and plant bodies to the microorganisms and then to detritus feeding organism called detrivores or decomposer and to other predators.

Litter —>Earthworms —>Chicken—>Hawk

Detritus food chain

  • The distinction between these two food chains is the source of energy for the first level consumers.
  • “A food web illustrates, all possible transfers of energy and nutrients among the organisms in an ecosystem, whereas a food chain traces only one pathway of the food”.
  • ECOLOGICAL PYRAMIDS : Shankar Ias Environment
  • The steps of trophic levels expressed in a diagrammatic way are referred to as ecological pyramids.
  • The food producer forms the base of the pyramid and the top carnivore forms the tip. Other consumer trophic levels are in between.
  • The pyramid consists of a number of horizontal bars depicting specific trophic levels which are arranged sequentially from primary producer level through herbivore, carnivore onwards.
  • The length of each bar represents the total number of individuals at each trophic level in an ecosystem.

Types of Ecological Pyramids

The ecological pyramids are of three categories-Shankar Ias Environment

  1. Pyramid of numbers, 
  2. Pyramid of biomass, and
  3. Pyramid of energy or productivity
  1. Pyramid of Numbers
  • This deals with the relationship between the numbers of primary producers and consumers of different levels.
  • Depending upon the size and biomass, the pyramid of numbers may not always be upright, and may even be completely inverted.
  1. Pyramid of numbers -upright
  • In this pyramid, the number of individuals is decreased from lower level to higher trophic level.
  • This type of pyramid can be seen in the grassland ecosystem.
  1. Pyramid of numbers -inverted
  • In this pyramid, the number of individuals is increased from lower level to higher trophic level.
  • A count in a forest would have a small number of oflarge producers, few numbers of big trees. This is because the tree being the primary producer
  • Few in number and would represent the base of the pyramid and the dependent herbivores (Example – Birds) in the next higher trophic level and it is followed by parasites in the next trophic level. Hyper parasites being at a higher trophic level represents higher in number.
  • A pyramid of numbers does not take into account the fact that the size of organisms being counted in each trophic level can vary
  • the pyramid of number does not completely define the trophic structure for an ecosystem.
  1. Pyramid of Biomass
  • In this approach individuals in each trophic level are weighed instead of being counted. This gives us a pyramid of biomass, i.e., the total dry weight of all organisms at each trophic level at a particular time. Biomass is measured in g/m2.
  1. Upward –pyramid For most ecosystems on land, the pyramid of biomass has a large base of primary producers with a smaller trophic level perched on top
  2. Inverted pyramid-In contrast, in many aquatic ecosystems, the pyramid of biomass may assume an inverted form
  1. Pyramid of Energy
  • An energy pyramid reflects the laws of thermodynamics, with the conversion of solar energy to chemical energy and heat energy at each trophic level and with loss of energy being depicted at each transfer to another trophic level.


  • Movement of these pollutants involves two main processes:
  1. Bioaccumulation
  • Refers to how pollutants enter a food chain. There is an increase in the concentration of a pollutant from the environment to the first organism in a food chain.
  1. Biomagnification
  • Refers to the tendency of pollutants to concentrate as they move from one trophic level to the next.
  • There is an increase in the concentration of a pollutant from one link in a food chain to another.
  • In order for biomagnification to occur, the pollutant must be: long-lived, mobile, soluble in fats, biologically active.
  • If a pollutant is not active biologically, it may biomagnify, but we really don’t worry about it much, since it probably won’t cause any problems Examples: DDT.

Biotic Interaction

  • The interaction between the organisms is fundamental for its survival and functioning of the ecosystem as a whole.

Type of Biotic Interaction

    1. Mutualism:
  • Both species benefit.
  • Example: in pollination, the pollinator gets food (pollen, nectar),  and the plant has its pollen transferred to other flowers for cross-fertilization (reproduction).
    1. Commensalism:
  • One species benefits, the other is unaffected.
  • Example: cow dung provides food and shelter to dung beetles. The beetles have no effect on the cows.
    1. Competition:
  • Both species are harmed by the interaction.
  • Example: if two species eat the same food, and there isn’t enough for both, both may have access to less food than they would if alone. They both suffer a shortage of food
    1. Predation and parasitism:
  • One species benefits, the other are harmed.
  • Example: predation—one fish kills and eats.. Parasitism: tick gains benefit by sucking blood; the host is harmed by losing blood.
    1. Amensalism:
  • One species is harmed, the other is unaffected.
  • Example: A large tree shades a small plant, retarding the growth of the small plant. The small plant has no effect on the large tree.
    1. Neutralism:
  • There is no net benefit or harm to either species. 
  • Perhaps in some interspecific interactions, the costs and benefits experienced by each partner are exactly the same so that they sum to zero.







Leave a Comment

Your email address will not be published. Required fields are marked *

Scroll to Top