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

Options

A. 0.01
B. 0.1
C. 0.4
D. 0.9

Explanation

To answer 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 Net Primary Productivity (NPP)**:
- NPP refers to the rate at which energy is stored as biomass by primary producers (like plants) in an ecosystem. It represents the energy available to consumers in the ecosystem.

2. **Identify the Role of Herbivores**:
- Herbivores are primary consumers that feed on plants. They play a crucial role in transferring energy from primary producers to higher trophic levels (carnivores).

3. **Energy Transfer in Ecosystems**:
- In a grazing food chain, energy transfer occurs at each trophic level. When herbivores consume plants, they utilize some of that energy for their own life processes (like respiration and maintenance).

4. **Quantifying Energy Utilization**:
- It is generally estimated that only about 10% of the energy consumed by herbivores is converted into biomass that can be passed on to the next trophic level (carnivores). The remaining 90% is used up in various life processes.

5. **Determine the Proportion of NPP Eaten by Herbivores**:
- Since only 10% of the herbivore productivity contributes to the next trophic level, it implies that 90% of the herbivore productivity is utilized for other processes. Therefore, in terms of NPP, we can conclude that 90% of the NPP is effectively consumed and utilized by herbivores.

6. **Select the Correct Answer**:
- Given the options provided (0.01, 0.1, 0.4, 0.9), the correct answer is 0.9, indicating that 90% of the NPP is eaten and digested by herbivores.

### Final Answer:
The amount of net primary productivity of a terrestrial ecosystem that is eaten and digested by herbivores is **0.9** (or 90%).