Basics –

• 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 –

1. 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

2. 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

Basics –

• 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 –

1. Organisms – individual
2. Population – A group of organisms of the same species inhabiting a given area.
3. Community – A group of different but interdependent species of plants or animals living their physical environment.
4. Ecosystem – A system formed by the interaction of a community of organisms with their physical environment.
5. Biome – A major biotic community characterized by the dominant forms of plant life and the prevailing climate.
6. Biosphere – Regions of the surface and atmosphere of the Earth where living organisms survive.

Habitat –

• The type of environment in which an organisms or group normally loves or occurs.
• Four major habitats –

1. Terrestrial
2. Freshwater
3. Estuarine
4. Ocean

Ecosystem

Basics –

• 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 –

1. A biotic factors –

• Climate factors –
• Temperature
• Humidity
• Light
• Atmospheric pressure
• Inorganic substances –
• Water
• Rocks
• Gases
• Minerals – nitrogen, phosphorous, sulphur etc.
• Organic substances –
• Carbohydrates
• Proteins
• Lipids

2. Biotic factors

• Producers – Autotrophs
• Plants
• Phytoplankton
• ) Phytoplankton are mainly unicellular algae
• ) Spirogyra
• ) Ulothrix
• Cladophora
• ) Diatoms
• Volvox
• Consumers – Heterotrophs
• ) Zooplankton
• ) Herbivores
• ) Carnivores
• ) Omnivores
• Decomposers – Saprotrophs or Detrivores
• ) Bacteria
• ) Fungi

Types of ecosystems –

1. 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.

2. Man made ecosystems –

• Dependent on solar energy- e.g. agricultural fields and aquaculture ponds.
• Dependent on fossils – e.g. urban and industrial ecosystems

Biome

Introduction –

• 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 –

1. Tropical rain forest

• Mostly found in the equatorial regions
• characterized by high temperature and heavy rainfall

2. 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

3. ­Taiga

• 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

4. Tundra

• 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

5. Savannah

• 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

6. Grassland

• 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.

7. Deserts

• 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.

Terrestrial Ecosystems

1. Forests

• ) Tropical rain forests
• Sub-types

1. Tropical evergreen forests
2. Tropical semi-evergreen forests

• Distribution
• 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
• Sub-types

1. Moist deciduous forests
2. 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.

2. Grasslands

• Subdivisions

1. Village grazing grounds
2. 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

3. Deserts

• 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.

4. 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.
• Sub-divisions

1. Eastern Himalayas or the Assam Himalayas
2. Central Himalayas or the Nepal Himalayas
3. Western Himalayas
4. North-West Himalayas or the Punjab Himalayas
5. Ghats
6. 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.

2. 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 Ecosystems

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

1. Fresh water ecosystem
2. Lotic (Running water) ecosystem

• Rivers
• Streams
• Creeks
• Rivulets

1. Lentic(Still water) ecosystem

• Lakes
• Ponds
• Swamps
• Reservoirs

2. Marine ecosystem

• Seas
• Arabian sea
• Bay of Bengal
• Ocean
• Indian Ocean
• Gulfs

1. Gulf of Mannar
2. Gulf of Kutchch
3. Gulf of Khambhat

• Continental shelf

4. Estuaries

• Estuaries include ecosystems of bays, river mouths and tidal marches.
• Estuaries are highly productive than river or sea ecosystems.

Ecotone

Definition –

• Ecotone is a zone of junction between two or more diverse ecosystems.

Examples of ecotone –

1. Mangroves – ecotone between marine and terrestrial ecosystem
2. Grassland
3. Estuary
4. 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.

Biological Relationships

Basics –

• Ecosystem is complex network of relationship among various organisms.
• Form of relationship

1. Intra specific relationship – relationship or interaction among individuals of the same species.
2. 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 –

1. 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.

2. 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 –

1. 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.

2. Predation –

• The relationships in which the predator captures, kills and eats an animal of another species or prey is called predation.

3. 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 –

• Neutralism
• 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 –

1. 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

2. 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.

3. Energy pyramid –

• Represents the amount of energy stored in each trophic level.
• Energy pyramid is never inverted.