Functioning Ecosystems

An ecosystem is a fundamental unit in nature, comprising living organisms (plants and animals) and their non-living environment. The biotic (living) components, such as producers and consumers, interact with their surroundings, making the ecosystem a functional unit.

All energy in an ecosystem originates from the sun, the primary energy source. Energy flows through the ecosystem via feeding relationships, where one organism consumes another, transferring energy.

Decomposers

Decomposers are organisms that feed on dead or decaying matter, including waste like urine and feces. They break down these materials through decay. Decomposers, also called saprophytes, are classified into two categories:

  1. Macro-decomposers: Larger decomposers like mushrooms, toadstools, and molds.
  2. Micro-decomposers: Microscopic decomposers, such as bacteria and fungi.

Decomposers release enzymes onto organic matter to break down complex substances like carbohydrates and proteins into simpler, soluble inorganic compounds. This process releases heat, with decomposers using a small portion of the nutrients and energy. The remaining nutrients are returned to the soil, air, and water, enriching the ecosystem.

Importance of Decomposers

Decomposers play a crucial role in maintaining ecosystem balance by recycling nutrients from dead organic matter. Their contributions include:

  1. Enriching soil with essential nutrients for plant growth.
  2. Facilitating nutrient recycling for ecosystem functioning.
  3. Producing carbon dioxide necessary for photosynthesis.
  4. Contributing to compost production.
  5. Assisting in waste management, such as sewage disposal.

Feeding Relationships

Living organisms obtain energy and nutrients through feeding relationships, which are integral to ecosystem functionality. Organisms are categorized into three main groups:

  1. Autotrophs (Producers): These organisms create their own food using inorganic substances through photosynthesis or chemosynthesis. Examples include green plants, algae, and certain bacteria.
  2. Heterotrophs (Consumers): These organisms rely on organic matter from other organisms for energy and nutrients. Consumers are further classified into:
    • Primary Consumers: Herbivores that feed directly on producers.
    • Secondary Consumers: Carnivores that eat primary consumers.
    • Tertiary Consumers: Predators that consume secondary consumers.
  3. Decomposers: These organisms feed on dead producers and consumers, aiding in decay and nutrient recycling.

Food Chains and Food Webs

Arrows indicate the direction of energy flow in a food chain. Energy is not cyclical; it cannot return to its source or be reused. Only 10% of energy transfers to the next trophic level, with energy diminishing at each stage, especially at the tertiary consumer level.

Food webs illustrate complex feeding relationships, comprising interconnected food chains. Human activities, like over-harvesting and introducing foreign species, can disrupt these webs.

Ecological Pyramids

Ecological pyramids represent relationships within ecosystems:

Thermodynamics in Ecosystems

Thermodynamics involves heat changes and energy transformations. The laws of thermodynamics describe energy flow within ecosystems:

  1. First Law: Energy cannot be created or destroyed, only transformed from one form to another.
  2. Second Law: Energy conversion results in energy loss as heat to the environment.

Application of Thermodynamics

Pyramids of Energy

The first law ensures that the total energy remains constant during transfers between trophic levels. The second law explains why energy is lost as heat during each transfer, giving the pyramid its shape.

Food Chains

In food chains, the first law describes energy transformations, such as converting chemical energy in plants to mechanical energy in animals. The second law highlights energy loss as heat at each step, limiting energy available to higher trophic levels.