Energy & Matter in Ecosystems: Flow, Trophic Levels & Cycles

Energy and Matter in Ecosystems

How Does Energy Flow?

Ecosystems maintain an open flow of energy because producers, like plants, transform solar energy into chemical energy through photosynthesis. This energy is then used and degraded as it passes through the trophic levels of consumers (herbivores, carnivores) and decomposers (bacteria, fungi). Ultimately, the activities of all living organisms in the ecosystem generate thermal energy as heat, which dissipates into the environment.

This energy flow is unidirectional because the solar energy entering the ecosystem is transformed into chemical energy within living organisms and eventually lost as heat.

Key Points:

• Typically, no more than 10% of the energy from one trophic level is transferred to the next. This energy transfer efficiency limits the number and size of organisms at higher trophic levels.
• The heat released by living organisms into the environment is degraded energy that cannot be reused by other organisms within the ecosystem.

Energy Flow Characteristics:

• Photosynthesizers (Producers): These organisms, like plants and algae, harness the power of sunlight. They synthesize organic matter, which stores chemical energy. Their metabolic activities release heat, which dissipates into the environment.
• Consumers and Decomposers: These organisms obtain the energy needed for their vital functions from consuming organic matter. Their activities also generate heat that is lost to the environment.

How Does Matter Flow?

All organisms in an ecosystem exchange materials with their environment while carrying out their vital functions. This flow of matter forms a closed loop, unlike the unidirectional flow of energy.

Certain nutrients, after being assimilated by organisms, become incorporated into the tissues of other organisms. Eventually, these nutrients are transformed back into inorganic substances and returned to the environment through decomposition.

What are Trophic Pyramids?

Trophic pyramids are graphical representations that simplify the trophic relationships between different levels within a biological community. They can be based on:

• Numbers: Indicate the number of individuals at each trophic level.
• Biomass: Represent the total weight of living matter present at each trophic level within an ecosystem.
• Energy: Show the amount of energy available at each trophic level.

What are Biogeochemical Cycles?

Living beings are composed of the same chemical elements that make up the Earth's systems. These elements move through relatively complex pathways known as biogeochemical cycles.

Types of Biogeochemical Cycles:

• Gaseous Cycles: In these cycles, elements circulate rapidly between different compartments, with the atmosphere serving as a major reservoir. Example: The Carbon Cycle.
• Sedimentary Cycles: These cycles have their main reservoir in the geosphere (Earth's crust). They are characterized by slower movement of elements, and the limited availability of these elements in the environment can act as a limiting factor for ecosystem productivity. Example: The Sulfur Cycle.