Productivity in ecosystem: Definition, Types, Diagram

What Is Productivity?

Ecosystem productivity is the rate of energy storage in organic matter by producers during photosynthesis or chemosynthesis. This energy feeds an entire ecosystem and promotes the growth of organisms, and their subsequent reproduction through different trophic levels. Therefore, understanding ecosystem productivity becomes very important, as it has a direct impingement on ecosystem stability, diversity, and sustainability.

Latest: NEET 2024 Paper Analysis and Answer Key 

Don't Miss: Most scoring concepts for NEET | NEET papers with solutions

New: NEET Syllabus 2025 for Physics, Chemistry, Biology

NEET Important PYQ & Solutions: Physics | Chemistry | Biology | NEET PYQ's (2015-24)

Types Of Productivity

Productivity in the ecosystem is categorised into two types:

Primary Productivity

Primary production is the rate at which energy is captured by autotrophs and then transformed into organic substances through photosynthesis or chemosynthesis. It is thus the base of the food web, sustaining herbivores and other consumers.

Gross Primary Productivity (GPP)

GPP refers to gross primary production, which is the amount of energy that autotrophs, mainly plants, capture through photosynthesis in a given area and time. This means the aggregate of the total energy absorbed by plants before being consumed in metabolic activities.

Net Primary Productivity (NPP)

NPP is simply the amount of energy remaining after the amount used by plants for respiration is deducted. It is the amount of energy available for growth and the reproduction of plants, and ultimately for consumption by herbivores and higher trophic levels.

Factors That Affect Primary Productivity

• Light Availability: It is the factor required for photosynthesis, dependent on latitude and seasonal changes.

• Temperature: Changes enzyme activity and metabolic rates of producers.

• Water and Nutrient Availability: It is critical to plant growth and photosynthetic activity.

• Methods of Measurement: Gross Primary Productivity accounts for the total quantity of energy absorbed by producers, while Net Primary Productivity has already deducted energy utilized in the process of respiration by plants.

Secondary Productivity

Secondary productivity refers to how fast consuming organisms convert the organic material of their food into new biomass. It is dependent upon the efficiency of energy transfer between trophic levels.

Factors that affect Secondary Productivity

• Availability of Primary Productivity: This gesture limits the amount of energy that would have otherwise been available for higher trophic levels.

• Trophic Structure and Efficiency: Efficiency decreases linearly as energy is moved up the food chain.

• Energy Transfer Efficiency: Only a portion of the energy is transferred from one tropic level to the next.

Factors Affecting Ecosystem Productivity

Ecosystem productivity is a product of abiotic and biotic factors undergoing complex interactions to determine both the efficiency and overall rate of energy transfer from one trophic level to another. Controlling factors are very important to understand since they help in the prediction of changes occurring in ecosystem dynamics and the management of natural resources sustainably.

Abiotic Factors: Light intensity and quality are important in that they have a direct impact on photosynthesis, with higher light availability normally raising primary productivity. Temperature—through its variation—affects metabolic processes and growth rates of organisms, hence overall productivity. The availability of water is critical for photosynthesis and the survival of plants, while that of nutrients, especially nitrogen and phosphorus, is important for plant growth and biochemical processes.

Biotic Factors: The diversity of species contributes toward this purpose by allowing niche complementarity, wherein different species efficiently use resources. It is expected that the productivity result will be impacted through trophic interactions such as predation and herbivory, because of their regulating effect on energy flow and nutrient cycling. Predation and herbivory control the balance between population dynamics and energy transfer efficiency to have balanced ecosystems.

Ecological Pyramids And Productivity

Ecological pyramids are graphical representations of energy, biomass, or the number of organisms at each stage of the trophic levels in an ecosystem, thereby giving information on the efficiency and structure of energy flow and matter cycling.

Pyramid Of Energy

The energy pyramid denotes the passage of energy from one level of a trophic system to the next in an ecosystem. Every higher level of the trophic structure receives less energy than that preceding it, due to loss in metabolic processes mainly as heat.

This is called the energy pyramid. As energy moves up from primary producers to apex predators, the quantity of energy goes on decreasing. In reality, only about 10% of the energy at one trophic level is revamped into the next, while all the rest is dissipated as heat.

Diagram: Pyramid Of Energy

Pyramid Of Biomass And Pyramid Of Numbers

The biomass pyramid shows the total mass of living organisms at each trophic level, while the pyramid of numbers refers to the count of individual organisms at each level. Both these pyramids describe the population structure and biomass distribution and must complement the very concept of the flow of energy through ecosystems.

Human Impact On Ecosystem Productivity

• Deforestation and habitat loss reduce primary productivity by destroying habitats and reducing photosynthetic surface area.

• Pollution and Nutrient Loading alters nutrient cycles and consecutively leads to eutrophication, and reduced productivity of the aquatic ecosystems.

• Climate Change and Global Warming may alter the temperature and precipitation regimes, thus having an overall effect on the growth and distribution of plants.

• Overexploitation of species reduces their biodiversity and, as such, the resiliency of ecosystems.