Components of an Ecosystem

Now that we know what an ecosystem is — a functional unit where biotic and abiotic components interact —
let’s understand what these components actually are and how they influence life.

Broadly, the components of an ecosystem are divided into:
1️⃣ Abiotic Components — non-living physical and chemical factors.
2️⃣ Biotic Components — living organisms and their biological roles.

☀️ Abiotic Components

These are the non-living parts of the ecosystem — like sunlight, temperature, rainfall, soil, water, air, pH, etc.
Although they don’t “live,” they control and limit the way life functions.

The Idea of “Limiting Factor”

Even though many abiotic factors influence survival, often one single factor becomes the deciding limit for an organism’s growth or distribution.
This single factor is called the limiting factor.

👉 Example 1:
In evergreen rainforests, rainfall is abundant, and vegetation is lush — yet, seeds don’t germinate easily.
Why? Because the topsoil is leached — heavy rains wash away nutrients.
So here, nutrient-poor soil is the limiting factor.

👉 Example 2:
In dense forests, even if soil is rich, saplings fail to grow due to lack of sunlight.
So here, light becomes the limiting factor.

Key idea: Even in an otherwise favorable environment, one limiting factor can determine survival.

⚙️ Major Abiotic Limiting Factors

Let’s discuss the key abiotic elements that shape ecosystems:

☀️ Light

• Life on Earth depends on sunlight — it drives photosynthesis and influences temperature and behavior.
• But too much or too little light can restrict growth.
• The UV component of sunlight is harmful to many organisms — causes mutations, damages tissues, etc.
• The spectral quality (i.e., color or wavelength) of light matters:
  • Only red and blue wavelengths are useful in photosynthesis.
  • Blue light → short, stunted plants.
  • Red light → promotes cell elongation (etiolated plants).
  • Ultraviolet light → dwarf plants.

🌧️ Rainfall

• All biochemical reactions occur in aqueous medium (water-based).
• Hence, rainfall decides not only plant growth but also type of vegetation — desert, grassland, rainforest, etc.

🌡️ Temperature

• It controls metabolism, growth, reproduction, and survival.
• Some organisms tolerate a wide temperature range — called eurythermal species (e.g., humans).
• Others can survive only in a narrow range — called stenothermal species (e.g., polar fish).

💨 Atmosphere

• 21% oxygen — supports respiration.
• 78% nitrogen — dilutes oxygen and prevents combustion.
• 0.038% CO₂ — though small, crucial for photosynthesis (primary production).

⚗️ Organic Compounds

• Include biomolecules like carbohydrates, proteins, lipids, and nucleic acids.
• These molecules drive energy transfer and biological processes.

🧪 Inorganic Compounds

• Elements like carbon, water, sulphur, nitrates, phosphates, and metal ions — essential for structure and metabolism.

🏔️ Altitude

• As we go higher, temperature drops → vegetation changes in vertical zones.
  (For example, tropical forests at the base, alpine meadows above, snow at the top.)

⚖️ Buffering Capacity of Earth

• Earth naturally maintains a neutral pH (~7) in soil and water.
• This stability (buffering) prevents extreme acidity or alkalinity — crucial for life.

🌊 Salinity

• The amount of dissolved salts in water or soil.
• Euryhaline species → tolerate wide salinity range (e.g., salmon).
• Stenohaline species → restricted to narrow range (e.g., goldfish).

🌾 Effect of Abiotic Factors on Terrestrial Autotrophs (Plants)

Let’s now see how these abiotic factors directly influence plants — the base of most ecosystems.

☀️ Light

• High-intensity light:
  → More energy → higher transpiration → roots grow more than shoots.
  → Leads to short stems, thick leaves, and smaller size.
• Low-intensity light:
  → Slower growth, delayed flowering, poor fruiting.
• When light intensity is below the minimum, CO₂ accumulates → plants stop growing.

❄️ Frost

• Frost freezes soil moisture, so roots can’t absorb water → plants die of transpiration stress.
• Ice crystals form in plant tissues → increase salt concentration → cell dehydration.
• Frost also causes canker formation — diseases caused by fungi, bacteria, or viruses.

🌨️ Snow

• Shortens vegetative period (growing season).
• Acts as an insulating blanket, protecting seedlings from extreme cold.
• But excess snow can break branches or uproot trees due to its weight.

🔥 High Temperature

• Leads to coagulation of protoplasmic proteins — cell death.
• Disturbs balance between respiration and photosynthesis.
• Causes desiccation (drying out) of tissues and moisture loss.
  (Some bacteria survive high temperatures due to special heat-stable proteins.)

🌾 Nitrogen

• A crucial limiting nutrient — both plants and soil microbes compete for it.
• Hence, nitrogen availability often controls productivity in both natural and agricultural ecosystems.

🌿 Dieback

• “Dieback” means progressive death of plant parts, usually from the tips backward.
• It’s an adaptive mechanism to survive drought or harsh conditions.
• The root stays alive while shoots die.
  Examples: Sal, Red Sanders, Silk-cotton trees.

🧬 Biotic Components

Now we move to the living part of the ecosystem.
Biotic components are divided based on how they obtain food or energy.

A. Primary Producers (Autotrophs)

• These are self-nourishing organisms — make their own food using sunlight or chemicals.
• Includes green plants, photosynthetic bacteria, and cyanobacteria (blue-green algae).
• In aquatic ecosystems, the main producers are microscopic algae (phytoplankton).

B. Consumers (Heterotrophs)

• “Hetero” means others → they depend on others for food.
• Cannot make their own food, so they eat plants or animals (or both).

Consumers are divided into two groups:

(1) Macro-consumers (Animals)

They feed on large, visible food sources.

Type	What they eat	Example
Primary consumers (Herbivores)	Plants	Sheep, Rabbit, Deer
Secondary consumers	Herbivores	Wolves, Dogs, Snakes
Tertiary consumers	Other carnivores	Lions (can eat wolves), Large snakes
Omnivores	Both plants & animals	Humans, Bears, Pigs

(2) Micro-consumers

These are microscopic organisms that feed on or break down organic matter.

Type	Mode of Nutrition	Example
Phagotrophs	Ingest (eat) organic matter or organisms	Amoeba
Osmotrophs	Absorb dissolved organic matter via osmosis	Some bacteria, fungi
Saprotrophs (Decomposers)	Break down dead material to obtain nutrients	Bacteria, Fungi (mushrooms)
Detritivores	Feed on dead organic particles (detritus)	Earthworms, Nematodes, Arthropods

🧩 These decomposers and detritivores play a vital role in recycling nutrients — returning them to the soil for plants to reuse, completing the ecosystem cycle.

🌀 In Summary

Component	Type	Examples	Function
Abiotic	Non-living	Light, Temp, Rainfall, Soil	Set the limits and conditions for life
Biotic – Producers	Autotrophs	Plants, Algae	Capture energy and make food
Biotic – Consumers	Heterotrophs	Herbivores, Carnivores, Omnivores	Transfer energy through food chains
Biotic – Decomposers	Micro-consumers	Bacteria, Fungi, Earthworms	Recycle nutrients back into ecosystem