What is an Ecosystem?

The concept of an ecosystem, introduced by A.G. Tansley in 1935, refers to a system formed by the interaction between living organisms and non-living components of the environment. An ecosystem comprises biotic components, which include living organisms, and abiotic components, such as physical factors like temperature, rainfall, wind, soil, and minerals.

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Types of Ecosystems

Ecosystems can be broadly categorized into two types:

Natural Ecosystems

Governed by natural conditions, these ecosystems are further divided into:

• Terrestrial Ecosystems: Examples include forests, grasslands, and deserts.
• Aquatic Ecosystems: These are classified into:
  • Freshwater Ecosystems: These can be either lentic (standing water) like ponds, pools, and ditches or lotic (running water) like rivers, streams, and springs.
  • Marine Ecosystems: Examples include oceans and seas.

Artificial Ecosystems

Also known as man-made ecosystems, these are controlled by humans. Examples include cropland ecosystems and aquariums.

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Components of an Ecosystem

Abiotic Components

These are the non-living physical and chemical factors of the environment.

• Inorganic Materials: These participate in material cycles, such as carbon, nitrogen, CO2, and H2O.
• Organic Compounds: Present in dead organic matter, including carbohydrates.
• Climatic and Edaphic Factors:
  • Climatic Factors: These include physical environmental factors like light and temperature.
  • Edaphic Factors: These pertain to the soil.

Abiotic Factors in Detail:

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Biotic Components:

The living components of an ecosystem form a community of organisms that interact and depend on each other. These include:

• Producer Organisms (Autotrophs): These organisms, mainly green plants, synthesize their own food through photosynthesis.
• Consumer Organisms (Heterotrophs): These organisms depend on others for food. They are classified into:
  • Herbivores: Animals that eat only plants, such as cows, buffaloes, goats, and deer.
  • Carnivores: Animals that eat other animals. These can be:
    • Secondary Consumers: Small carnivores that feed on herbivores, like frogs, lizards, birds, and foxes.
    • Tertiary Consumers: Large carnivores that feed on secondary consumers, such as lions, tigers, and birds of prey.
  • Omnivores: Animals that eat both plants and animals, including humans, dogs, crows, and bears.
• Decomposer Organisms (Saprotrophs): These organisms, such as certain bacteria and fungi, consume dead organic matter, breaking it down into inorganic materials.

Decomposition Process

Decomposers play a critical role in breaking down complex organic matter into simpler inorganic materials like carbon dioxide, water, and various nutrients. This process, known as decomposition, involves decomposers such as fungi and bacteria, which break down detritus (dead plant parts and animal remains).

Scavengers: Unlike decomposers, scavengers like vultures do not break down matter at the cellular level. They consume dead organisms and contribute to the ecosystem by cleaning up carrion.

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Impact of Human Activities on Ecosystems

Human activities can significantly affect ecosystems, often leading to imbalances. For example, hunting can shorten food chains, disrupting the balance of ecosystems and the biosphere as a whole. The Sahara Desert's formation is an example of how human activities can destabilize ecosystems.

Consider the following scenarios in a food chain (Grass → Deer → Lion):

1. Removal of Lions: Without lions, deer populations would increase unchecked, leading to overgrazing and potentially eliminating grass and other plants, turning forests into deserts.
2. Removal of Deer: Without deer, lions would lack sufficient food, leading to their population decline. This could disrupt other food chains and force hungry lions to seek food outside the forest, potentially endangering humans and domestic animals.
3. Removal of Producers: Without grass and plants, neither deer nor lions could survive.