The net primary productivity of an ecosystem is :

Options

A. Total weight of green plants - repiratory losses
B. Total weigth of green plants + respiratory losses
C. Respiratory losses alone
D. None of the above

Answer

**Step-by-Step Solution:**

1. **Understanding Net Primary Productivity (NPP):**
- Net Primary Productivity (NPP) is a key concept in ecology that refers to the amount of organic matter (biomass) produced by plants in an ecosystem after accounting for the energy lost through respiration.

2. **Defining Gross Primary Productivity (GPP):**
- Gross Primary Productivity (GPP) is the total amount of energy captured by plants through photosynthesis. It represents the total biomass produced before any losses due to metabolic processes.

3. **Calculating NPP:**
- To find NPP, we subtract the energy lost due to metabolism (respiration) from GPP. The formula is:
\[ NPP = GPP - \text{Respiratory Losses} \]

4. **Evaluating the Options:**
- Option 1: "Total weight of green plants minus respiratory losses" - This correctly describes NPP as it aligns with the formula.
- Option 2: "Total weight of the green plants" - This is incorrect as it does not account for respiratory losses.
- Option 3: "Respiratory losses" - This is incorrect as it does not represent NPP.
- Option 4: "None of the above" - This is also incorrect since option 1 is correct.

5. **Conclusion:**
- The correct answer is option 1: "Total weight of green plants minus respiratory losses."

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