- The totality of surrounding conditions in which organisms survives is called environment.
- Environment is composed of both living and non living components.
- Proper balance between biotic and a biotic factors is essentials for the survival of living organisms.
Factors of Environment –
- Biotic factors –
- Plants – Converts a biotic factor into food for animals through photosynthesis.
- Animals – All living organisms depend on other organisms for food and in-turn become food for other organism.
e.g. grass–>deer–>tiger–>vulture–>micro-organisms–>back to minerals deeded by grass
- A biotic Factors –
- Light – Essential for photosynthesis and movement
- Water –
- Medium for biochemical reactions
- Regulation of body temperature
- Habitant for aquatic plants and animals
- Temperature –
- Essential for the functioning of all environment cycles.
- Certain range of temperature and humidity is essential for survival of Organisms
- Atmosphere –
- Contains life supporting gases.
- Sub-stratum –
- Soil, deep water vents or any surface supporting life forms.
- Ecology is the scientific study of inter-relationships between organisms and their environment.
- The term ecology was first coined in 1869 by the German biologist Ernest Haeckel.
Levels of ecological organisms –
- Organisms – individual
- Population – A group of organisms of the same species inhabiting a given area.
- Community – A group of different but interdependent species of plants or animals living their physical environment.
- Ecosystem – A system formed by the interaction of a community of organisms with their physical environment.
- Biome – A major biotic community characterized by the dominant forms of plant life and the prevailing climate.
- Biosphere – Regions of the surface and atmosphere of the Earth where living organisms survive.
- The type of environment in which an organisms or group normally loves or occurs.
- Four major habitats –
- Ecosystem: A system formed by the interaction of a community of organism with their physical environment.
- Ecosystem is comprised of complex interaction between its biotic(living) and a biotic(non-living) components.
Factors of ecosystem –
- A biotic factors –
- Climate factors –
- Atmospheric pressure
- Inorganic substances –
- Minerals – nitrogen, phosphorous, sulphur etc.
- Organic substances –
- Biotic factors
- Producers – Autotrophs
- ) Phytoplankton are mainly unicellular algae
- ) Spirogyra
- ) Ulothrix
- ) Diatoms
- Consumers – Heterotrophs
- ) Zooplankton
- ) Herbivores
- ) Carnivores
- ) Omnivores
- Decomposers – Saprotrophs or Detrivores
- ) Bacteria
- ) Fungi
Types of ecosystems –
- Natural ecosystems –
- Ecosystems totally dependent on solar radiation
e.g. forests, grasslands, oceans, lakes, rivers, and deserts.
- Ecosystems dependent of solar radiation and alternative energy source such as wind, rain and tides.
e.g.- tropical rains forests, tidal estuaries and coral reefs.
- Man made ecosystems –
- Dependent on solar energy- e.g. agricultural fields and aquaculture ponds.
- Dependent on fossils – e.g. urban and industrial ecosystems
- Biome is a large naturally occurring of flora and fauna occupying a major habitat, e.g. forest or desert.
- Biomes are characterized by different types of climate, flora, fauna and soil types.
- Climate of biome and abundance of flora and fauna are determined mainly by the level temperature and precipitation.
Types of biomes –
- Tropical rain forest
- Mostly found in the equatorial regions
- characterized by high temperature and heavy rainfall
- Temperature Deciduous Forest
- Found across the regions of Central Southern Europe, East and North America, Western China, Japan, New Zealand etc.
- Trees like birch, oak, maple and cherry are found here
- characterized by moderate temperature and rainfall
- Northern subarctic coniferous forests (Boreal forest)
- spreading across much of subarctic N America and Eurasia, with tundra to the north and steppe to the south
- Trees such as spruce, pine and firs are abundant here
- Animals like Siberian tiger, minks, elks, puma, and wolverines are found here
- A vast treeless plain in the Arctic regions where the subsoil is permanently frozen
- characterized by lichens, mosses and dwarfed vegetation
- Mostly found animals include polar bear, lemmings, reindeer, arctic fox and arctic hare
- Found mostly in mid tropical regions were comparatively moderate precipitation is seen
- They are most extensive in Africa
- Animals such as lions, cheetah, antelopes, buffaloes, zebras, elephants, rhinoceros, hyena and many rodents flourish here
- These are regions dominated by grasslands
- Characterized by temperature conditions with low rainfall.
- Supports large herbivores like bison and antelope, large species of birds, rodents, wolves etc.
- These are interior regions of the continents with sporadic rainfall and low humidity.
- They are characterized by plants like cactus and euphorbias and animals such as reptiles, few mammals, and birds.
- ) Tropical rain forests
- Tropical evergreen forests
- Tropical semi-evergreen forests
- Found in places of high rainfall (around 200 cm) and sunlight.
- Regions include Western Ghats, West Bengal, Orissa, A&N Islands and north-eastern India
- Flora and Fauna
- Trees grow up to 60 cm and above
- This region has high biodiversity
- Important trees in this forest include ebony, mahogany and rosewood.
- ) Tropical deciduous forests
- Also called as monsoon forests
- Moist deciduous forests
- Dry deciduous forests
- Formed in regions having 75 cm to 200 cm of annual rainfall
- Major regions include
- eastern slopes of Western Ghats
- north eastern parts of the peninsular plateau
- Valley of the Himalayas
- Chhotanagpur plarteau
- parts of Madhya Pradesh, Bihar and Orrisa
- Important trees of these forests are teak, sal, and sandalwood
- ) Temperature broad leaf forests
- Occurs between 1500-2400 m altitudes in western Himalayas
- Flora and Fauna
- Oak species are abundant which shed leaves during summer.
- characterised by a dense canopy of trees but gasses are generally absent
- The oak forests are often rich in epiphytic flora
- Temperature or coniferous forests
- These types of forests are found in the Himalayas over 1700 to 3000 m altitude.
- Coniferous forests are characterised by an evergreen canopy of long needle like leaves.
- Major trees include
- Pine (Pinus wallichiana)
- Deodar (Cedrus deodara)
- Cypress (Cypressus torulosa)
- Spruce (Picea simthiana)
- Siver fir (Abies pindrow)
- ) Alpine and tundra forests
- Alpine and tundra forests grow at altitudes above 3600 m.
- The trees include silver, pine, juniper and birch
- High altitude vegetation such as lichen and mosses are found here
- Tidal forests
- They are found along the costs and rivers
- Sundari trees or mangroves are abundant in this region.
- Village grazing grounds
- Low pastures of dry regions
- Flora and Fauna
- Grasslands support a large of herbivores, birds and large animals.
- one horned rhinoceros of India is a grassland animal
- Thar Deserts
- Thar desert in Rajasthan is an extension of the Sahara desert through Arabian and Persian deserts.
- They extend from Punjab, Haryana, Rajasthan to Gujarat state.
- Rann of Kutch
- Rann of Kutchch – Bhuj in Gujarat forms a separate zone with in Thar desert due to its different climate conditions.
- Rann of Kutchch supports living corals, pearl oyster, sea turtles and migratory birds like kingfisher, cranes, ibis and herons.
- Flora and Fauna
- Only some thorn forests and dry open grasslands are found here.
- Food crops include bajra, millet, wheat, barley, maize, jowar and guwar.
- Medical plants found here are mehndi, hak, isabgole and gugal.
- Threatened bird species – Great Indian Bustard, Cranes and Sand Grouse.
- Threatened mammals – Asiatic lion, wild ass, bats, scaly and eater, desert fox, Indian gazelle, four horned antelope and white browed Buchchat.
- Mountains – Himalayas
- Himalayas are spread over Afghanistan, Pakistan, India, Nepal, Bhutan and China.
- Himalayas are spread partially or completely over 12 states –Jammu and Kashmir, Himachal Pradesh, Uttaranchal, Sikkim, West Bengal, Arunachal Pradesh, Assam, Nagaland, Manipur, Tripura, Mizoram and Meghalaya.
- Eastern Himalayas or the Assam Himalayas
- Central Himalayas or the Nepal Himalayas
- Western Himalayas
- North-West Himalayas or the Punjab Himalayas
- Western Ghats
- Also called as Sahyadris
- They run parallel to the west coast of peninsular India.
- They pass spread six states namely Gujarat, Maharashtra, Goa, Karnataka, Tamil Nadu and Kerala.
- Eastern Ghats
- They are spread through the states of Orissa, Andhra Pradesh and Tamil Nadu.
- The eastern ghats do not form a continuous range because the great rivers Mahanadi, Godavari and Krishna cut across them.
- United Nations Conference on Environment held in Rio de Janeiro in 1992 discussed the issue of conservation of this region.
Aquatic Zones –
- Aquatic ecosystems are divided into distinct life zones, with regions of relativity distinct plant and animal life.
- The differences between various aquatic zones are due to-
- depth of sunlight penetration
- levels of dissolved nutrients
- level of salinity
- temperature of the water
- abundance of food
- Fresh water ecosystem
- Lotic (Running water) ecosystem
- Lentic(Still water) ecosystem
- Marine ecosystem
- Arabian sea
- Bay of Bengal
- Indian Ocean
- Gulf of Mannar
- Gulf of Kutchch
- Gulf of Khambhat
- Continental shelf
- Estuaries include ecosystems of bays, river mouths and tidal marches.
- Estuaries are highly productive than river or sea ecosystems.
- Ecotone is a zone of junction between two or more diverse ecosystems.
Examples of ecotone –
- Mangroves – ecotone between marine and terrestrial ecosystem
- River Banks
Characteristics of ecotone –
- It may be very narrow or quite wide.
- Ecotone is a zone tension
- Ecotone may contain specially evolved organisms are entirely different from the adjoining communities.
- Ecosystem is complex network of relationship among various organisms.
- Form of relationship
- Intra specific relationship – relationship or interaction among individuals of the same species.
- Inter specific relationship – relationship or interaction among individuals of different species.
- Inter specific relationship may be direct and close or indirect and remote.
Types of relationships –
Positive Relationship –
- Commensalism –
- The relation between two different kinds of organisms when one receives benefits from the other without damaging it.
- g. relationship between trees and epiphytic plants, ferns, mosses etc.
- Mutualism –
- Relationship between two different species of organisms that are interdependent; each gains benefit from the other.
- This is a close association between two species in which both the species benefit.
- Symbiotic mutualism: Mutualism in which the interacting can no longer live without each other as they depend totally on each other to survive.
Negative Relationships –
- Amensalism –
- Relationship in which one species harms of restricts the other species without itself being affected by the presence of the other species.
- g. Penicillium kills the bacteria through pencillin to have greater availability of food.
- Predation –
- The relationships in which the predator captures, kills and eats an animal of another species or prey is called predation.
- Parasitism –
- The relation between two different kinds of organisms in which one receives benefits from the other by causing damage to it.
- Many organisms like animals, bacteria and viruses are parasites of plants and animals.
Neutral Relationships –
- Relationship between two species which do interact but do not affect each other in neither positive nor negative ways.
Food Chains, Food webs and ecological pyramids
Food Chain –
- Community of organisms where each member is eaten in turn by another member is called food chain.
- Trophic level : Each successive stage in the food chain is called Trophic level e.g. Grasses>Deer>Tiger>Vulture, Grass represent first trophic level, deer the second and so on.
- In every stage, some energy is lost into the system as heat energy and is not available to the next trophic level.
- Types of food chains –
- Grazing food chains – Autotrophs>Herbivores>Carnivores
- Detritus food chains – Dead organic matter>Detritus Feeders>Carnivores
Food Web –
- Food web is a network of interconnected food chains in an ecosystem.
- An ecosystem may consist of several interrelated food chains called food web in totally.
- Single organisms can take part in multiple food chains.
- Energy flow in food web is similar to the flow of energy in food chains.
- Difference –
- A food chain traces only one pathway of the food or energy transfer among few organisms in an ecosystem.
- A food web illustrates, all possible transfers of energy and nutrients among the organisms in an ecosystem.
Ecological Pyramid –
- Ecological pyramids are the graphic representations of trophic levels in an ecosystem.
- Ecological pyramids are pyramidal in shape.
Types of pyramids –
- Pyramid of numbers –
- Upright –
- Represents the number of organisms at each trophic level.
- The number of individuals decreases gradually form lower trophic level to higher trophic level.
- g. Grassland ecosystem
- Inverted –
- The number of individuals increases gradually from lower trophic to higher trophic level.
- g. Forest ecosystem
- Biomass pyramid –
- In the pyramid of biomass, individuals in each trophic level are weight instead of being counted.
- In calculates the total dry weight of all organisms at each trophic level at a particular time.
- Biomass pyramid of terrestrial is upright.
- Biomass pyramid of aquatic ecosystem is inverted.
- Energy pyramid –
- Represents the amount of energy stored in each trophic level.
- Energy pyramid is never inverted.