Which one of the following options represents the correct order of decreasing average net primary productivity (g / m2 / year) in natural ecosystems?
Show Hint
- Swamp and marshes>Tropical forests>Temperate forests>Temperate grasslands>Tundra
- Swamps and marshes>Tropical forests>Temperate forests>Tundra>Temperate grasslands
- Tropical forests>Swamps and marshes>Temperate forests>Tundra>Temperate grasslands
- Tropical forests>Swamps and marshes>Temperate forests>Temperate grasslands>Tundra
The Correct Option is A
Solution and Explanation
Step 1: Core idea of NPP.
NPP measures the rate at which plants convert solar energy into biomass after respiration. High water and nutrient availability \(\Rightarrow\) high NPP; cold or dry conditions \(\Rightarrow\) low NPP.
Step 2: Typical relative productivities.
- Swamps & marshes: among the highest (\(\sim 2000{-}2500 \; g\,m^{-2}\,yr^{-1}\))
- Tropical forests: very high (\(\sim 1800{-}2200\))
- Temperate forests: moderate (\(\sim 1000{-}1300\))
- Temperate grasslands: lower (\(\sim 400{-}800\))
- Tundra: lowest (\(\sim 100{-}200\))
Step 3: Arrange in decreasing order.
\[ \text{Swamps \& marshes } > \text{ Tropical forests } > \text{ Temperate forests } > \text{ Temperate grasslands } > \text{ Tundra} \]
This ordering matches Option (A). Other options misplace grasslands or tundra, or invert swamps and tropical forests.
Final Answer: \[ \boxed{\text{(A) Swamps \& marshes > Tropical forests > Temperate forests > Temperate grasslands > Tundra}} \]
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