2.3 Flows of energy and matter

Understand the energy absorbed by producers in the context of the Earth’s energy budget

Energy is absorbed by producers through the process of photosynthesis. Producers, mainly plants and some types of algae, capture solar energy and convert it into chemical energy in the form of glucose and other organic compounds through photosynthesis. This absorbed energy is used for their growth and reproduction. Producers play a critical role in capturing solar energy and converting it into biomass, making it available as food for other organisms in the ecosystem.

Primary productivity

refers to the rate at which autotrophic organisms (mainly plants) in an ecosystem convert solar energy into chemical energy through photosynthesis or chemosynthesis. It is typically measured in units such as grams of organic matter (usually carbon) per square meter per year (g/m²/yr) or energy units like kilocalories per square meter per year (kcal/m²/yr).

Secondary Productivity

is the rate at which heterotrophic organisms (consumers) in an ecosystem convert the organic matter obtained from primary producers into their own biomass through processes like consumption and digestion. It is also measured in units like grams of organic matter or energy per square meter per year (g/m²/yr or kcal/m²/yr).

Limiting Factors of Primary Productivity (Link to Biome Productivity):

They vary depending on the biome, but they generally include:

• Light: In aquatic ecosystems, light availability can be a limiting factor, especially in deep waters.

• Nutrients: Nutrient availability, particularly nitrogen and phosphorus, can limit primary productivity in both terrestrial and aquatic ecosystems.

• Temperature: Temperature can limit productivity in terrestrial ecosystems, with colder temperatures reducing the rate of photosynthesis.

• Water: In arid regions, water availability is a significant limiting factor for primary productivity.

• Carbon Dioxide: In some cases, carbon dioxide availability can limit productivity, particularly in marine ecosystems.

The term maximum sustainable yield in the context of net productivity

The term "Maximum Sustainable Yield" (MSY) refers to tGPP is the total rate at which primary producers (plants) convert solar energy into chemical energy through photosynthesis in an ecosystem. It is measured in units like grams of carbon per square meter per year (gC/m²/yr) or energy units like kilocalories per square meter per year (kcal/m²/yr)

Define GPP

GPP is the total rate at which primary producers (plants) convert solar energy into chemical energy through photosynthesis in an ecosystem. It is measured in units like grams of carbon per square meter per year (gC/m²/yr) or energy units like kilocalories per square meter per year (kcal/m²/yr)

Define NPP

NPP is the rate at which primary producers convert solar energy into chemical energy minus the energy they expend in cellular respiration. NPP represents the energy available for consumption by heterotrophic organisms and is a crucial measure of an ecosystem's productivity.

Define GSP

Define GSP

GSP is the total rate at which secondary consumers (heterotrophic organisms) convert the organic matter obtained from primary consumers into their own biomass.

Define NS

Define NSP

P

NSP is the rate at which secondary consumers convert the organic matter obtained from primary consumers into their own biomass, minus the energy expended in respiration.