Explain the structure and functions of an ecosystem.

(N/A) The interaction of biotic and abiotic components results in a physical structure that is characteristic for each type of ecosystem.
Identification and enumeration of plant and animal species of an ecosystem provide its species composition.
Vertical distribution of different species occupying different levels is called stratification. For example,trees occupy the top vertical strata or layer of a forest,shrubs the second,and herbs and grasses occupy the bottom layers.
The components of the ecosystem function as a unit when considering the following aspects: $(i)$ Productivity,$(ii)$ Decomposition,$(iii)$ Energy flow,and $(iv)$ Nutrient cycling.
The ethos of an aquatic ecosystem can be understood by the example of a small pond.
This is a fairly self-sustainable unit and a simple example that explains the complex interactions that exist in an aquatic ecosystem.
$A$ pond is a shallow water body in which all the above-mentioned four basic components of an ecosystem are well exhibited.
The abiotic component is the water with all the dissolved inorganic and organic substances and the rich soil deposit at the bottom of the pond.
The solar input,the cycle of temperature,day length,and other climatic conditions regulate the rate of function of the entire pond.
The autotrophic components include the phytoplankton,some algae,and the floating,submerged,and marginal plants found at the edges.
The consumers are represented by the zooplankton,the free-swimming,and bottom-dwelling forms.
The decomposers are the fungi,bacteria,and flagellates,especially abundant at the bottom of the pond.
This system performs all the functions of any ecosystem and of the biosphere as a whole,i.e.,conversion of inorganic into organic material with the help of the radiant energy of the sun by the autotrophs; consumption of autotrophs by heterotrophs; decomposition and mineralization of the dead matter to release them back for reuse by the autotrophs. These events are repeated over and over again.
There is a unidirectional movement of energy towards the higher trophic levels and its dissipation and loss as heat to the environment.