Interaction of biotic and abiotic components result in a physical structure that is characteristic for each type of ecosystem. One can derive species composition of an ecosystem by identifying and enumerating plant and animal species Vertical distribution of different species occupying different levels is called stratification. For example, trees occupy top vertical strata or layer of a forest, shrubs the second and herbs and grasses occupy the bottom layers.
The components of the ecosystem are seen to function as a unit, when you consider the following aspects:
(i) Productivity
(ii) Decomposition
(iii) Energy flow
(iv) Nutrient cycling
PRODUCTIVITY
- Primary production is defined as the amount of biomass or organic matter produced per unit area over a time period by plants during photosynthesis. It is expressed in terms of weight or energy.
- Productivity is the rate of biomass production. It is expressed in terms of to compare the productivity of different ecosystems.
- Productivity can be divided into gross primary productivity (GPP) and net primary productivity (NPP).
- Gross primary productivity of an ecosystem is the rate of production of organic matter during photosynthesis. A considerable amount of GPP is utilised by plants in respiration.
- Net primary productivity is the available biomass for the consumption to heterotrophs (herbivores and decomposers).
- Gross primary productivity minus respiration losses (R), is the net primary productivity (NPP).
- GPP – R = NPP
- Secondary productivity is defined as the rate of formation of new organic matter by consumers.
- Primary productivity depends on the plant species inhabiting a particular area.
It also depends on a variety of environmental factors, availability of nutrients and photosynthetic capacity of plants. Therefore, it varies in different types of ecosystems.
