Productivity in the Ecosystem

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What is Productivity in Ecosystem?

Productivity in an ecosystem refers to the percentage of energy that enters the ecosystem in the form of biomass at a particular trophic level. It is the rate at which biomass is formed in the ecosystem. At each trophic level in the ecosystem, a characteristic amount of biomass is present. Energy enters the ecosystem through primary producers. Thus, the total productivity of its ecosystem is measured based on two aspects- Primary productivity and secondary productivity.


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Primary Productivity

Primary productivity is the generation of biomass by autotrophy. The autotrophy could be photoautotrophs or chemoautotrophs. In photoautotrophs, living things synthesize their food from inorganic elements in the presence of light that acts as a source of energy. Plants are the primary autotrophs and with the help of photosynthesis, they create organic matter from inorganic substances. Whereas, Chemoautotrophy is the process by which simple living organisms of the ecosystem like bacteria and archaea, derive energy from chemical processes other than photosynthesis.


Primary Productivity Further has two Aspects:

Gross Primary Productivity

The rate at which photosynthetic primary producers that are the plants incorporate energy from the sun is called gross primary productivity. The organic matter or biomass thus produced is referred to as the gross primary productivity. Gross primary productivity is dependent on environmental factors and photosynthetic elements.


Net Primary Productivity

Some of the energy produced by gross productivity is lost by activities like respiration and metabolic heat loss. Net productivity is what remains after this loss of energy. It is what is available to the primary consumers at the next trophic level. Net primary productivity is estimated by subtracting loss of energy by gross primary productivity.


Therefore, Net primary productivity = GPP – Energy lost.


The net energy is stored in plants which are then used as food for the animals that feed on plants. Researchers consider the net primary productivity which is the amount of organic matter produced in a community in a given time. Nearly 170 billion tons of net primary productivity occurs over the entire biosphere per year.


Net primary productivity varies among ecosystems and is dependent on factors like solar energy input, weather conditions, moisture levels, carbon dioxide levels in the ecosystem, availability of nutrients, and interactions in the community. These factors influence the number of autotrophs that capture light energy and how efficiently they can perform their role.


Secondary Productivity

Secondary productivity is influenced by heterotrophs in the ecosystem. It is the energy accumulated at the consumer level. The biomass generation in secondary productivity is driven by the transfer of organic compounds between trophic levels through feeding. So, it is not like productivity in the primary level because it keeps moving from one organism to another. It can also be stated as the rate of increase in the biomass of heterotrophs. Animals, fungi, bacteria, and numerous other protists influence Secondary Production.


Unit of Productivity

Productivity is given by units of mass per unit volume (or surface) per unit time.


Movement of Energy Between Trophic Levels

The energy passes from one trophic level to next when organic molecules from an organism's body are eaten by another organism. The transfer of energy between trophic levels is not completely efficient. only about 10% of the energy stored as biomass in one trophic level gets stored as biomass in the next trophic level. That is from primary producers to primary consumers. Here, net productivity drops by a factor of ten from one trophic level to the next.

FAQ (Frequently Asked Questions)

1. Which Ecosystem Shows the Highest and Lowest Productivities?

Ans. As a result of structural complexity, the highest gross primary productivity is found in coral reefs ecosystem. It is also known as the tropical rain forest. And the most productive ecosystems in the world are temperate and tropical forests. Desert and tundra are the least productive ecosystem.

2. Under What Conditions do All Ecosystems Become Equally Productive?

Ans. All ecosystems become equally productive under the conditions of drought. This is because, in conditions of drought, tropical forests can be as efficient at using water as desert ecosystems.

3. What is Primary Productivity?

Ans. Primary productivity is the generation of biomass by autotrophy. The autotrophy could be photoautotrophs or chemoautotrophs. In photoautotrophs, living things synthesize their food from inorganic elements in the presence of light that acts as a source of energy. Plants are the primary autotrophs and with the help of photosynthesis, they create organic matter from inorganic substances. Whereas, Chemoautotrophy is the process by which simple living organisms of the ecosystem like bacteria and archaea, derive energy from chemical processes other than photosynthesis.

4. What is Gross Primary Productivity?

Ans. The rate at which photosynthetic primary producers that are the plants incorporate energy from the sun is called gross primary productivity. The organic matter or biomass thus produced is referred to as the gross primary productivity. Gross primary productivity is dependent on environmental factors and photosynthetic elements.

5. What is Net Primary Productivity?

Ans. Some of the energy produced by gross productivity is lost by activities like respiration and metabolic heat loss. Net productivity is what remains after this loss of energy. It is what is available to the primary consumers at the next trophic level. Net primary productivity is estimated by subtracting loss of energy by gross primary productivity.

Therefore, Net primary productivity= GPP – Energy lost.

6. What is Secondary Productivity?

Ans. Secondary productivity is influenced by heterotrophs in the ecosystem. It is the energy accumulated at the consumer level. The biomass generation in secondary productivity is driven by the transfer of organic compounds between trophic levels through feeding. So, it is not like productivity in the primary level because it keeps moving from one organism to another. It can also be stated as the rate of increase in the biomass of heterotrophs.