2. Organic Substances:
They are present in the biomass or in the environment. They form the living body and influence the functioning of the ecosystem. Examples: Carbohydrates, proteins, lipids, humus, etc. % Climate Factors: They have a strong influence on the ecosystem. Water: Plants and animals receive the water from the soil and the Earth’s surface. Water is the medium by which mineral nutrients enter and distributed in plants. For the survival of animals, water is necessary.
Soil provides nutrients, water, a structural growing medium for organisms. Atmospheric air: Within ecosystems, the atmosphere provides oxygen for respiration of organisms and carbon dioxide for photosynthesis in plants.
Sunlight is necessary for photosynthesis. It is used to heat the atmosphere in ecosystems.
All the living components of the environment constitute the biotic components.
Depending on their self-food producing capability, biotic components are of following types,
(i) Producers or Autotrophic components
Producers are self-nourishing organisms (so they are called autotrophs). They contain chlorophyll and are capable of converting carbon dioxide and water, in the presence of sun-light into carbohydrates through photosynthesis. In the process, they give out oxygen.
Autotrophy is of Following Types:
These are the producers who fix energy from the sun and store it in complex organic compounds.
Examples Green plants, some bacteria, algae.
(ii) Chemoautotrophs (chemosynthesizers)
They are bacteria that oxidize reduced inorganic substances (typically ammonia and sulphur compounds) and produce complex organic compounds.
Example nitrifying bacteria in the soil under ground
(iii) Consumers (or heterotrophic components):
Consumers depend on producers to obtain their energy for survival. They utilize, rearrange and decompose the organic matter produced by autotrophs.
Consumers are classified as herbivores, carnivores and top carnivores depending on their food habits.
(a) Herbivores (or Primary Consumers): They feed on green plants (autotrophs) to obtain energy for survival.
Seed-eaters are also known as Granivores. Fruit-eaters are also known as Frugivores.
Examples Grasshoppers, rabbits, goats, cows, horses, etc
(b) Carnivores (or Secondary Consumers): They feed on primary consumers. Examples Lizard, fox, hawk, etc
(c) Top Carnivores (or Tertiary Consumers): They eat the flesh of carnivores and are not killed or eaten by other animals.
Examples Lions, tigers, vultures, etc
The decomposers are also known as saprotrophs (i.e. sapros = rottten; trophs = feeder). They feed on dead organic matter (from producers and consumers). They transform complex organic compounds back into simple inorganic substances like C02, H2O, phosphates, and sulphates. Examples Bacteria, fungi, other microbes, etc
Fallen leaves, parts of dead trees, and faecal wastes of animals are termed as detritus. The consumers that feed on detritus are known as detrivores. Examples Ants, termites, earthworms, crabs, etc.
Decomposers and detrivores are essential for the long-term survival of a community. Their vital role is to complete the matter cycle. Enormous wastes of plant litter, dead animal bodies, animal excreta, and garbage would collect on Earth without them.
Furthermore, important nutrients would remain indefinitely in dead matter. The producers would not get their nutrients, and life would be impossible without detrivores and decomposers.