Ecosystem Dynamics: Trophic Levels, Pyramids, and Energy Flow

Habitat and Ecological Niche Defined

A habitat is the physical place where a species lives. It provides the natural conditions the species needs to survive. An ecological niche is the way a species relates to the biotic and abiotic factors in an ecosystem.

Two species can share the same habitat, although they do not usually occupy the same ecological niche.

Understanding Trophic Dynamics

Trophic dynamics is the system that describes the position of a living being in a food chain. The system uses trophic levels to explain what an organism eats or is eaten by.

Trophic Pyramids: Graphic Representations

A trophic pyramid is a graphic representation of a particular characteristic at each trophic level. These pyramids are specific to individual ecosystems. The trophic levels are represented by superimposed layers of equal height placed on top of each other. There are three main types:

• Number Pyramid

  Represents the number of individuals at each trophic level per unit of area or volume. The structure is typically:

  1. The base shows the producers.
  2. Next come the primary consumers.
  3. Then the secondary consumers.
  4. Finally, the tertiary consumers.

• Biomass Pyramid

  This represents the biomass, or amount of organic matter which forms an individual, a trophic level, or an ecosystem. It is measured in grams (g) or kilograms (kg) of dry organic matter per unit area or volume.

• Energy Pyramid

  Represents the energy stored at each trophic level at a certain time. It also shows the flow of energy through the trophic levels.

How Are Matter and Energy Transmitted?

There are two fundamental types of processes governing matter and energy transmission:

1. A One-Way Flow of Energy

   Energy flows through the trophic levels, starting with photosynthesis. The process follows these steps:

   1. First, energy from the Sun enters the ecosystem.
   2. Then, autotrophic organisms (producers) convert this light energy into chemical energy.
   3. Next, the energy is stored in the producers’ organic matter.
   4. Finally, it flows to the other trophic levels in the ecosystem.

2. A Closed Cycle of Matter

   In this process, matter is recycled, not lost. The cycle works as follows:

   • The producers take in inorganic matter and convert it into organic matter.
   • This organic matter is passed on to the consumers.
   • When producers and consumers die, decomposers convert the remains back into inorganic matter.
   • This inorganic matter will be used again by producers, completing the cycle.