Plants \(\rightarrow\) Grasshopper \(\rightarrow\) Frog \(\rightarrow\) Snake \(\rightarrow\) Hawk

Organism at T₄ level will receive 0.1 Joule of energy as per ten percent law.

Nutrients will retain in the ecosystem through biogeochemical cycles. Various nutrients present in soil and atmosphere enter the organism at various trophic levels through food and other process and are cycled back to their origin. Thus the nutrients are not lost but retained in the ecosystem.

Ecosystem services are defined as the benefits that people derive from nature. Study on ecosystem services acts as an effective tool for gaining knowledge on ecosystem benefits and their sustained use. Without such knowledge gain, the fate of any ecosystem will be at stake and the benefits they provide to us in future will become bleak.

There are three zones, littoral, limnetic and profundal. The littoral zone, which is closest to the shore with shallow water region, allows easy penetration of light. It is warm and occupied by rooted plant species. The limnetic zone refers the open water of the pond with an effective penetration of light and domination of planktons. The deeper region of a pond below the limnetic zone is called profundal zone with no effective light penetration and predominance of heterotrophs. The bottom zone of a pond is termed benthic and is occupied by a community of organisms called benthos (usually decomposers).

Detritus food chain is a type of food chain which begins with dead organic matter which is an important source of energy. A large amount of organic matter is derived from the dead plants, animals and their excreta. This- type of food chain is present in all ecosystems. The transfer of energy from the dead organic matter, is transferred through a series of organisms called detritus consumers (detritivores)- small carnivores -large (top) carnivores with repeated eating arid being eaten respectively. This is called the detritus food chain.
Fallen leaves   ➝    Earth worm   ➝    Black bird     ➝         Hawk
Detritus               Detritivores      Small carnivores  Top carnivores

Main source of energy for the grazing food chain is the Sun. It begins with the first link, producers (plants). The second link in the food chain is primary consumers (mouse) which get their food from producers. The third link in the food chain is secondary consumers (snake) which get their food from primary consumers. Fourth link in the food chain is tertiary consumers (eagle) which get their food from secondary consumers.
Grass       ➝             Mouse        ➝              Snake         ➝                Eagle
Producers       Primary consumers    Secondary Consumers    Tertiary consumers

(I) Buying and use only ecofriendly products and recycle them.
(II) Growing more trees.
(III) Choosing sustained farm products (vegetables, fruits and greens, etc.)
(IV) Reduce the use of natural resources.
(V) Recycle the waste and reduce the amount of waste you produce.
(VI) Reduce consumption of water and electricity.
(VII) Reduce or eliminate the use of house-hold chemicals and pesticides.
(VIII) Maintain your cars and vehicles properly. (In order to reduce carbon emission).
(IX) Create awareness and educate about ecosystem protection among your friends and family members and ask them to find out solution to minimise this problem.

Pyramid of number
(i) In a forest ecosystem the pyramid of number is different in shape, it is because the base (T ₁) of the pyramid occupies large sized trees (producer) which are lesser in number.
(ii) Herbivores (T₂) occupying second trophic level, are more in number than the producers (T₁).
(iii) In final trophic level (T₄) tertiary consumers (lion) are lesser in number than the secondary consumers (T₃).
(iv) Therefore, the pyramid of numbers in forest ecosystem looks spindle-shaped.
Pyramid of biomass
(i) In forest ecosystem, there is a gradual decrease in biomass of organisms at successive trophic levels from producers to top carnivores (Tertiary consumer). Therefore, the pyramid of biomass looks upright.

Detritus food chain
(i) This type of food chain begins with dead organic matter which is an important source of energy.
(ii) A large amount of organic matter is derived from the dead plants, animals and their excreta.
(iii) This type of food chain is present in all ecosystems
(iv) The transfer of energy from the dead organic matter is transferred through a series of organisms called detritus consumers. (detrivores)-Small carnivores -large (top) carnivores with repeated eating and being eaten respectively.