📌 Chapter Snapshot
1869
Term 'Ecology' Coined
1935
Term 'Ecosystem' Coined
10%
Energy Transfer Rate
3
Types of Ecological Pyramids
- Ecosystem is the study of natural relationships between the environment and biotic community.
- This chapter covers: ecosystem components & types, food chain & trophic levels, ecological pyramids, ecological niche, ecological imbalance, biogeochemical cycles, and biomes.
⚡ QUICK RECALL
Ecology (1869, Ernst Haeckel) came before Ecosystem (1935, A.G. Tansley) — a 66-year gap between the two foundational terms.
🌿 Ecosystem — Introduction
- Ecosystem = study of natural relationships between environment and biotic community.
- Term 'Ecology' first used → Ernst Haeckel (1869 AD).
- Term 'Ecosystem' first used → A.G. Tansley (1935 AD).
⚠ EXAM TRAP
Don't mix up who coined which term — Haeckel gave "Ecology" (1869), Tansley gave "Ecosystem" (1935). Different people, different decades.
🧩 Components of Ecosystem
| Biotic Components | Abiotic Components |
|---|---|
| Producers, Consumers (Primary/Secondary/Tertiary), Decomposers (Bacteria & Fungi), Reducers | Organic, Inorganic, Climatic |
Types of Ecosystem
- Terrestrial Ecosystem → Forest, Grassland, Desert Ecosystem (has most biomass).
- Aquatic Ecosystem → Marine (Permanent), River/Lake, Wetlands.
🔗 Food Chain
- Food chain = transfer of energy from one organism to another, from lower to higher trophic level.
- Energy transfer rate: only 10% (Lindeman's Law) — unidirectional flow.
- Humans act as Primary and Secondary Consumers.
- Types of Food Chain: (1) Grazing Food Chain, (2) Decomposer Food Chain.
⚠ EXAM TRAP
Only 10% of energy passes to the next trophic level (Lindeman's Law) — the remaining 90% is lost as heat/respiration. A very common numeric MCQ.
🔺 Trophic Level / Food Chain Pyramid
| Trophic Level | Examples |
|---|---|
| Producer | Green plants, algae, photosynthetic organisms, etc. |
| Primary Consumer (Herbivore) | Herbivores — cow, goat, etc. |
| Secondary Consumer | Small carnivores — snake, cat, etc. |
| Tertiary Consumer | Eats primary and secondary consumers |
| Quaternary Consumer | Top Carnivores — lion, tiger, vulture, etc. |
⚡ QUICK RECALL
Food Web = network of interconnected food chains within an ecosystem — not a single linear chain.
☠ Biomagnification
- Excessive concentration of toxic substances in higher trophic levels of the food chain.
- Examples: DDT, BHC, 2-4D, Mercury, etc.
🔻 Ecological Pyramid
Concept given byCharles Elton (1933 AD)
- A pyramid diagram showing the number, biomass, or accumulated energy of producers and consumers at each trophic level.
| Type | Shape | Details |
|---|---|---|
| Pyramid of Number | Upright (Aquatic) / Inverted (Terrestrial) | Shows number of organisms at each trophic level |
| Pyramid of Biomass | Upright (Terrestrial) / Inverted (Aquatic) | Shows total biomass at each trophic level |
| Pyramid of Energy | Always Upright | Shows energy at each trophic level |
⚠ EXAM TRAP
Pyramid of Energy is ALWAYS upright — no exceptions — because energy always decreases at higher trophic levels. Number & Biomass pyramids CAN be inverted depending on ecosystem type.
🏠 Ecological Niche
Concept given byCharles Elton (1927) & G.E. Hutchinson
- The local habitat region of various species of organisms/plants.
- Shows the structural and functional role of the organism in its ecosystem.
⚖ Ecological Imbalance
- Increase or decrease in the population of a particular species weakens adaptive capacity.
- Examples: Deforestation, Cyclone, Drought.
⚡ QUICK RECALL
Highest productivity — Terrestrial: Tropical Rainforest | Aquatic: Estuaries.
🔄 Biogeochemical Cycles
- Movement of nutrients through various components of the ecosystem.
- Gaseous Cycles → Nitrogen Cycle, Carbon Cycle, Oxygen Cycle, Water Cycle.
- Sedimentary Cycles → Phosphorus Cycle, Sulphur Cycle.
⚠ EXAM TRAP
Water Cycle is classified as a Gaseous Cycle here (along with N, C, O) — Phosphorus & Sulphur are the only Sedimentary Cycles. Don't misclassify Phosphorus as gaseous.
🌎 BIOME — Major Types
- Tropical Evergreen Forest
- Monsoon Forest
- Savanna
- Mediterranean
- Temperate Grassland
- Temperate Coniferous Forest
- Tundra
- Marine Pelagic
📋 Master Quick-Revision Table
| Topic | Key Fact |
|---|---|
| Term 'Ecology' — First used | Ernst Haeckel (1869 AD) |
| Term 'Ecosystem' — First used | A.G. Tansley (1935 AD) |
| Biotic Components | Producers, Consumers (Primary/Secondary/Tertiary), Decomposers (Bacteria & Fungi), Reducers |
| Abiotic Components | Organic, Inorganic, Climatic |
| Terrestrial Ecosystem | Forest, Grassland, Desert | Most biomass |
| Aquatic Ecosystem | Marine (Permanent), River/Lake, Wetlands |
| Energy Transfer in Food Chain | 10% (Lindeman's Law) | Unidirectional flow |
| Types of Food Chain | 1. Grazing Food Chain | 2. Decomposer Food Chain |
| Food Web | Network of interconnected food chains within an ecosystem |
| Biomagnification | Excessive toxic concentration in higher trophic levels | Eg: DDT, BHC, Mercury |
| Ecological Pyramid — Concept | Charles Elton (1933 AD) |
| Pyramid of Energy | Always Upright |
| Pyramid of Number | Upright: Aquatic | Inverted: Terrestrial |
| Pyramid of Biomass | Upright: Terrestrial | Inverted: Aquatic |
| Ecological Niche | Charles Elton (1927) & G.E. Hutchinson | Structural & functional role of organisms |
| Highest Terrestrial Productivity | Tropical Rainforest |
| Highest Aquatic Productivity | Estuaries |
| Gaseous Cycles | Nitrogen, Carbon, Oxygen, Water Cycle |
| Sedimentary Cycles | Phosphorus Cycle, Sulphur Cycle |
| Types of Biomes | Tropical Evergreen, Monsoon Forest, Savanna, Mediterranean, Temperate Grassland, Temperate Coniferous, Tundra, Marine Pelagic |