CAPF AC 2022 Q7: Environment & Ecology – Ecosystems & Ecology Concepts
- (a) forest floor
- (b) forest soil
- (c) forest canopy
- (d) forest litter
Answer: (c) forest canopy
Explanation
Where a forest meets the sunlight
How to think: the question asks for the layer where energy exchange takes place and some sunlight is sent back to space.
Sunlight strikes the top of a forest first.
The top layer of leaves and branches is the canopy.
| Layer | Position | What happens |
|---|---|---|
| Canopy | Top, formed by tree crowns | Receives most sunlight; reflects some, absorbs the rest; most photosynthesis |
| Understorey | Below the canopy | Dim light; shrubs and young trees |
| Forest floor | Ground | Very little light reaches it |
| Litter | Dead leaves on the ground | Decomposition and nutrient recycling |
| Forest soil | Below the litter | Stores water and nutrients |
The idea behind it: the share of sunlight a surface reflects is its albedo.
A forest canopy has a low albedo, so it absorbs most of the light.
Answer: (c) forest canopy.
Why each option is right or wrong
- (a) Incorrect. The forest floor gets only a small share of the sunlight.
- (b) Incorrect. The forest soil lies below everything and does not face the sky.
- (c) CORRECT. The canopy is the boundary layer that exchanges energy with the atmosphere.
- (d) Incorrect. Litter is dead plant matter on the ground, far below the sunlight.
Key point
Forest layers from top: emergent, canopy, understorey, shrub layer, forest floor. The canopy is the active surface for energy exchange, photosynthesis and rainfall interception.
Remember
Canopy = the forest's sunlit boundary layer.
Common mistakes
- Marking the forest floor, thinking the ground reflects the sunlight.
- Mixing up litter (dead leaves) with the living canopy above.
- Forgetting that in a dense forest little light passes below the canopy.
Exam tip
Educated guess: only one option is at the top of the forest, facing space. Floor, soil and litter are all at the bottom.
Sources
- NCERT Class XII Biology — Ecosystem (structure and stratification) and Organisms and Populations
- NCERT Class XI Geography — Fundamentals of Physical Geography (solar radiation, heat balance and albedo)