How much of the net primary productivity of a terrestrial ecosystem is eaten and digested by herbivores ?

Options

A. `1%`
B. `10%`
C. `40%`
D. `90%`

Answer

To solve the question of how much of the net primary productivity (NPP) of a terrestrial ecosystem is eaten and digested by herbivores, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Definitions**:
- **Gross Primary Productivity (GPP)**: This is the total amount of biomass produced by photosynthesis in a given area.
- **Net Primary Productivity (NPP)**: This is the amount of biomass that remains after the energy used by plants for respiration is subtracted from GPP. It represents the energy available to herbivores and other consumers.

2. **Identify the 10% Rule**:
- In ecological terms, there is a rule known as the "10% rule" which states that only about 10% of the energy at one trophic level is transferred to the next level. This rule is primarily applicable to energy transfer between trophic levels.

3. **Apply the 10% Rule to NPP**:
- If we consider that the NPP of a terrestrial ecosystem is a certain amount (for example, 100 units), then according to the 10% rule, only 10% of that NPP is available to the herbivores.

4. **Calculate the Amount Eaten by Herbivores**:
- From the NPP, if we take 10% as the amount that is eaten and digested by herbivores, we can conclude that:
- Amount eaten by herbivores = 10% of NPP
- If NPP = 100 units, then herbivores eat 10 units.

5. **Conclusion**:
- Therefore, the answer to the question is that herbivores eat and digest approximately **10% of the net primary productivity (NPP)** of a terrestrial ecosystem.

### Final Answer:
Herbivores eat and digest approximately **10% of the net primary productivity of a terrestrial ecosystem**.

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