Primary productivity depends upon the producers (plants species) their photosynthetic potential, soil, climate and other environmental factors of an ecosystem. They are seldom similar in different ecosystem. Therefore, primary productivity varies from ecosystem to ecosystem.

1. The rate of decomposition is regulated by temperature and soil moisture, as they influence the activities of decomposers.
2. The trophic have a warm/hot and humid condition; such a condition is favourable for the decomposers and hence they speed up the process of decomposition.

Function: To meet the deficit which occurs due to imbalance in the rate of influx and efflux.

(i) Structure of a pyramid of number is given below:

(ii) Differences between pyramid of number and biomass in a tree ecosystem are:

All organisms/animals which depend directly or indirectly on plants for their food are called consumers.
Consumers are of the following types:
(i) Primary consumers
They are the organisms/animals which depend directly on producers for their food;they are also called as herbivores,e.g. deer, rabbit, zooplanktons.
(ii)Secondary consumers
Secondary consumers are those animals which depend on the primary consumers for their food; they are primary carnivores, e.g frogs,hyena.
(iii)Tertiary consumers
Tertiary consumers are those animals which depend on the secondary consumers for their food;they are the secondary carnivores, e.g. lion, eagle, kite, etc.

Pond - an Ecosystem
1. Pond is a fairly self-sustainable unit that shows even complex interactions of an aquatic ecosystem.
2. It is a shallow water body in which all the major/basic components of an ecosystem are well exhibited.
3. The abiotic components ar:
(i) Water with all the dissolved inorganic substance.
(ii) The rich soil deposit at the bottom.
(iii) The solar input.
(iv) The cycle of temperature.
(v) day length.
(vi) Climatic factor.
1. The producers or autotrophic components include phytoplanktons, some algae, floating and submerged and marginal plants.
2. The consumers are represented by
(i) zooplanktons,
(ii) f ree-swimming animals,
(iii) bottom dwelling animals.
1. The decomposers are the bacteria and fungi that are found at the bottom.
2. This system performs all the function of an ecosystem.
(i) Conversion of inorganic materials into organic compounds with the help of radiant energy of sun.
(ii) Consumption of autotrophs  by heterotrophs, (food chain/food web), decomposition and mineralisation (nutrient cycling), etc.