Ecosystem

All plants and animals are adapted to live only in their respective geographical areas.

An ecosystem is a self contained area composed of all the different organisms living in it, interacting with each other and also interacting with the physical conditions prevailing in the area.

The term ecosystem is derived from the Greek word “Oikos” which means a “house” a dwelling place with he inhabitants living together and interacting with each other and also with their physical environment in some definite ways.

This interaction is primarily for food. That is, eat or get eaten.

Example: Forest Ecosystem

In a forest, the relationship among the organisms is the same as anywhere else. The food producers and food consumers depending on each other.

Vegetation: Dense growth of trees with a variety of shrubs, bushes, grasses.

All these plants produce their own food through photosynthesis and are therefore self-food producers or autotrophs.

Next, there are plant-eating organisms or herbivores. They are the primary consumers.

Next come the animals that eat the herbivores. These are called carnivores or secondary consumers.

Grass → Grasshoppers → Frog → Snake

Here the snake is a tertiary consumer.

If the snake is eaten by a peacock, then the peacock belongs on another food level. Food levels are also called trophic levels. They are the food obtaining steps in a food chain.

Organisms in all the different trophic levels die due to some cause or another.

If they are not killed by predators, and their dead body is not eaten or consumed by the flesh-eating scavengers, it will spoil the environment.

The dead material is further broken down by the bacteria and fungi in the soil, helping in the return of nutrients back to the soil for the plants to grow.

Producers → Primary consumers → Secondary Consumers → Tertiary Consumers

Components

In an ecosystem, there are two categories of components: living components (BIOTIC) and non-living components (ABIOTIC).

BIOTIC

Trophic Level 1- Green Plants

Starting point of nourishment.

Self food-producers.

Autotrophs.

Trophic Level 2- Plant eating animals/Herbivores/Primary Consumers

Vast variety of animals that directly eat plants or parts of them.

Trophic Level 3- Flesh eating animals/Carnivores/Secondary Consumers

Animals which capture their prey.

Their prey is strictly herbivore.

Trophic Level 4- Second Rank flesh eaters/Tertiary Consumers

Eat the secondary Consumers.

There is another category of organisms that feed on dead material of any organism in any of the Trophic levels.

Categorised into Scavengers, Detritivores, Decomposers.

Scavengers feed on dead animal or plant material.

Detritivores and Decomposers feed on the remains left by the scavengers.

Detritivores like earthworms and slugs decompose dead plant and animal matter or even faeces and release nutrients by this breakdown.

Decomposers obtain nutrition by absorbing nutrients that are released by this breakdown.

ABIOTIC

Non-living

  1. Sunlight

For production of food in green plants by photosynthesis

  1. Air

  • To provide oxygen to plants and animals for respiration, ans carbon dioxide for photosynthesis.

  • To serve as a medium of flight to birds and insects

  • To serve as an agent for dispersal of seeds, pollen grains and fruits.

  1. Water

Received as rainfall and absorbed as soil water, taken by the plants or consumed by the animals in drinking from puddles and rivers.

  1. Temperature

Hot, mild or cold temperature of a region influences the body functions of the plant and animals living in that region.

  1. Soil

Foremost component of the forest and for other ecosystems as well.

Trees, grass and bushes grow in soil.

Soil contains water and mineral nutrients required by plants,

Soil also contains microorganisms responsible for breakdown of dead decaying material and release of nutrients into the soil.

Dwelling place for burrowing animals.

Food Chains

The linear sequence of organisms in which each organism eats a lower member and/or gets eaten by a higher member.

Food webs

A network of several interconnected food chains.

Green Plant(Producer)→ Grasshopper(Primary Consumer)→ Frog(Secondary Consumer)→ Snake(Tertiary Consumer)→Eagle(Quaternary consumer)

A food chain can have only put 6 Trophic Levels.

A simplified version of a food web would function as such:

Plants grow, an animal eats the plant, another animal ate the animal who ate the plant, both animals and plant die, eaten by microorganisms who convert this organic material into organic compounds in soil that can be taken up again by plants.

Existence of plant life is integral to the continuity and development of most ecosystems.

The environment is made up of two kinds of matter: Organic and inorganic.

Plants are the only link in the food chain capable of transferring inorganic chemicals into organic compounds for consumption of other living things in the ecosystem.

The nutrients are passed on through Trophic levels in food webs.

If plants were not capable of transferring these materials, then animals would not have the required nutrients to survive.

Plants do this by extracting nutrients from the ground; nutrients that the animals are not able to consume directly from the soil.

Advantages of Food Webs

The food webs permit alternative foods.

These ensure a better chance of survival of an organism, in case, any one of its food source is scarce.

It simply means that a food web provides more stability to the ecosystem than a food chain.

Food Pyramids

Grass→Deer→Tiger

A grown tiger must have eaten several deer in its lifetime and a grown up deer must have consumed a lot of grass in its own lifetime.

Largest mass is consumed at the first level (grass→deer) which does not lead to the same mass of flesh of the deer.

Next, the total mass of flesh of deer eaten by the tiger in its lifetime, must have been several times its own body mass.

Interdependence

Every organism is interdependent on each other.

For any species, the minimal requirement is more species on which it can feed.

Even a plant which produces its own food cannot survive alone, it is reliant on the microbes in the soil to break down the organic material into simpler organic nutrients.

Interdependence comes from interaction of two different species.

This interaction can e beneficial, harmful or neutral to one or both species.

Symbiosis-

In this interaction, both the species are benefitted.

Plants need the help of animals for pollinating their flowers and dispersing their seeds.

Animals get paid back in the form of juicy, nutritious fruits or nectar.

Lichens are another good example in which a fungus and a photosynthetic alga live in a symbiotic relationship.

Parasitism-

In this interaction, the parasite receives an advantage while the host receives a loss.

Parasites enjoy free lodging and meals at the cost of the host.

The life cycles of parasites are often complex, involving one or more hosts.

The malarial parasite, Plasmodium needs an intermediate host (vector)— a mosquito to spread to other hosts.

Human liver fluke (a nematode parasite) depends on two intermediate hosts (a snail and a fish) to complete its life-cycle.

The parasites harm the host- they may reduce the revival, growth and reproduction of the host.

Predation-

A predator catches and kills an animal for food.

Predation is nature’s way of transferring energy.

Although animals eating fruits are categorised as herbivores, they are, in broad ecological context, not very different from predators.

FLORA AND FAUNA OF FOREST ECOSYSTEM

Flora means rhe plants naturally occurring in a particular area and Fauna means the animals naturally occurring in a particular area.

Flora and Fauna of a forest is never the same around the world.

Different types of forests-

  1. Tropical Rain forests

Western coast of India, North East Himalayas.

Flora- Evergreen trees, Bamboos, Ferns, Shrubs

Fauna- Jungle cats, leopards, monkeys, flying squirrels, snakes, centipedes, millipedes, insects, snails

  1. Temperate Deciduous Forests

Eastern Coast of India

Flora- Teak, Sandalwood, Sal

Fauna- Moth, Beetles, Deer, Wolves, Foxes

  1. Coniferous Forests

Himalayas at an altitude of 1700-3000 metres

Flora- Fir and pine trees

Fauna- Squirrel, Dear, Goat, Wolves, Robin, Sparrow

Gir Forest (Gujarat)

Flora- Peepal, acacia, neem, wild bushes, grasses

Fauna- Bears, Dogs, Cats, Rats, Rabbits, Crows, Kites, Vultures, Lions

Jim Corbett National Park (Uttarakhand)

Flora-Pine trees, shrubs, grasses

Fauna- Tiger

Jaladpara Sanctuary (West Bengal)

Flora- Various kinds of trees, including banyan trees

Fauna- Rhinoceros

RISKS TO ECOSYSTEM

With increased industrialisation and scientific approach ot our life, the natural resources and rich natural heritage we have been preserving for centuries have begun dwindling greatly,

Any kind of imbalance in nature results into severe danger to our ecosystem.

Serious problems like-

  • Climate Change

  • Vector-borne diseases

  • Decay in wildlife

  • Food and water shortage

Exploitation of natural resources around the world has erupted into severe ecological degradation, which is definitely the biggest threat to proper functioning of our ecosystem.

NEED TO RESTORE AND CONSERVE THE ECOSYSTEM

  1. Assist nature by not disturbing its integrity and help restore its lost balance,

  2. By protecting our native natural resources like wildlife, rivers, forests etc.

  3. Radical changes have to be made in our thoughts to save and accumulate the natural resources, the very root of our life.