Basics of Energy and Environment Short Notes Part-2

ECOLOGY

Ecology is defined as a scientific study of the relationship of the living organisms with each other and with their environment

The term ‘Ecology’ was coined by the German zoologist Ernst Haeckel

ENVIRONMENT

It is the surroundings or conditions in which a person, animal, or plant lives or operates.

It comprises both living (biotic) and non living (abiotic) components.

The environment is defined as ‘the sum total of living, non-living components, surrounding an organism’

Each and everything with which we interact forms our environment

Components of Environment

Abiotic: Temperature, water, wind, atmospheric gases, gravity, soil etc.

Biotic: Green and non-green plants, decomposers, parasites, animals, humans etc.

ORGANISATIONS LEVEL IN ECOLOGY

1. Organism: Individual living being that has the ability to act or function independently. E.g. plant, animal, bacterium etc.
2. Population: Group of organisms usually of same species
3. Community: Group or association of population of two or more different species occupying the same geographical area and in a particular time
4. Ecosystem: Structural and functional unit of biosphere which consists of community of living beings and the physical environment
5. Biome: Community of plants and animals that have common characteristics for the environment they exist in. E.g. Tundra, Taiga, Temperate Deciduous Forest, Tropical rain forest, Desert etc.
6. Biosphere: Part of the earth where life exists. It comprises of atmosphere (air), hydrosphere (water) and lithosphere (land)

INTERACTIONS BETWEEN AND WITHIN THE SPECIES

Some common examples: 

Mutualism

Coral and Zooxanthallae: Coral provides habitat and Zooxanthallae provides food

Mycorrhizae: Myco (Fungi) provides shelter and rrhizae (root) provides food

Commensalism

Common Myna and Cattle

Cattle Egret and Cattle

Amensalism

Bread Mold: Mold releases penicillin that kills bacteria

Other types of interactions

Symbiotic relationship is that interaction between different species in which both are getting benefitted and where species are living in close vicinity of each other

Probiotic relationship is that interaction between different species in which atleast one organism is getting benefitted but other is not suffering loss

ECOTONE

Zone of junction between two or more diverse ecosystems. e.g. the mangrove forests is an ecotone between marine and terrestrial ecosystem

NICHE

Unique functional role or place of a species in an ecosystem.

• Habitat Niche: where it lives
• Food Niche: what it eats or decomposers and what species it competes with
• Reproductive Niche: how and when it reproduces
• Physical and Chemical Niche: temperature, land etc.  

FUNCTIONS OF AN ECOSYSTEM

It can be studied under the following three headings

• Energy Flow
• Nutrient Cycling
• Ecological Succession

ENERGY FLOW

Flow of energy from producer to top consumers is called energy flow

The study of trophic level interaction in an ecosystem gives an idea about the energy flow through the ecosystem

The energy always flow from lower to higher trophic level 

The trophic level interaction involves following three concepts

1. Food Chain
2. Food Web
3. Ecological Pyramids

FOOD CHAIN
It is a sequence of organisms that feed on one another. A food chain starts with producers and ends with top carnivores

Food Chains are broadly classified as:

• Predatory Food Chain: Primary source of energy is sunlight. It is generally larger in size.

Grass → Grasshopper → Frog → Snake → Eagle

Phytoplanktons → Zooplanktons → Small fishes → Large fishes

Diatoms → Crustaceans → Herring → Meckerel → Tuna → Humans

• Detritius Food Chain: Primary source of energy is dead matter. It is generally smaller.

Liiter → Earthworms → Chicken → Hawk

FOOD WEBS

Interconnected food chains are known as food webs. They are also known as Elotonian Webs

Energy Transfer Law or Tropical Efficiency or Ecological Efficiency

Ecological efficiency means energy transferred from one trophic level to another trophic level

ECOLOGICAL PYRAMIDS

The steps of trophic levels expressed in a diagrammatic way are referred as ecological pyramids.

The producer forms the base of the pyramid and the top carnivore forms the tip.

The ecological pyramids are of three categories:

1. Pyramid of numbers
2. Pyramid of biomass
3. Pyramid of energy

Pyramid of Numbers: Graphic representation of the total number of individuals of different species, belonging to each trophic level in an ecosystem. It can be upright or inverted.

Pyramid of biomass: Individuals in each trophic level are weighted instead of being counted. It can be upright or inverted.

Pyramid of energy:  It reflects the laws of thermodynamics, with conversion of solar energy to chemical energy and heat energy at each level. It is always upright.

Ecological Succession (Biotic Succession)

Process through which existing species are replaced by new species

• Primary Succession: Succession at a place where life doesn’t exist in the past
• Secondary Succession: Succession at a place where life existed in the past
• Autogenic Succession: Succession caused by bio-community (living community)

 BIODIVERSITY

Bio means life and diversity means variations

Types of diversity

• Genetic diversity: Intra species diversity
• Species diversity: Inter species diversity
• Ecosystem diversity: Diversity with the surroundings

Total 17 countries in the world are called Mega-diverse countries. Of them, Brazil is the most mega diverse country

Organism  Population  Community  Ecosystem  Biome  Biosphere (Biodiversity increases)

Latitudinal Diversity Gradient

As latitude increases, Biodiversity decreases; From Poles to Tropics, biodiversity increases

Altitudinal Diversity Gradient

As atlitude increases, biodiversity decreases

Warm and tropical regions are the most bio diverse. Amazon rainforest has high biodiversity

Corals (Rainforest of sea) have high biodiversity.“Coral Triangle” hence known as Amazon of the sea

BIODIVERSITY HOTSPOTS (Term given by Norman Myers in 1998)

Criteria for any location to be declared as biodiversity hotspot

1. Minimum 0.5% of the species of 1500 species of vascular plants are endemic
2. Minimum 70% or more of the natural vegetation or the primary vegetation is lost

On the basis of these criteria, there are total 35 biodiversity hotspots in the world. The forest of East Australia being the latest one

BIODIVERSITY HOTSPOTS RELATED TO INDIA

There are 4 biodiversity hotspots related to India

1. Western Ghats
2. Himalaya
3. North-Eastern India
4. Great Nicobar

Western Ghats

1. Western Ghats is one of the 8 hottest hotspots in the world
2. 39 sites from the Western Ghats together declared as World Heritage Sites
3. Western Ghats covers 6 Indian states, viz. Gujarat, Maharashtra, Goa, Karnataka, Kerala and Tamil Nadu
4. For Western Ghats conservation purpose, Western Ghats Experts Ecology Panel headed by Madhav Gadgil was appointed in 2010. To have more holistic approach, Kasturirangan Committee headed by Kasturi Rangan was appointed

NOTE

• 35 Biodiversity Hotspots account around 2.3% of total geographical area but support 50% of endemic plant species
• Around 85% of the original vegetation has been lost in these Biodiversity hotspots

THREATS TO BIODIVERSITY

1. Habitat loss and fragmentation
2. Allien species (also called introduced species or non-native species or exotic species). Example, Parthenium (Carrot grass), Lantana, water hyacinth
3. Coextinction (Key species): Species having a disproportionately high impact on the surrounding or other species depend on them
4. Over-exploitation
5. Human population growth
6. Climate change
7. Pollution
8. Deforestation and degradation of forest
9. Industrialization
10. Ozone depletion 

Thanks.

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