Which one of the following ecosystem types has the highest annual net primary productivity

Options

A. Temperate deciduous forest
B. Tropical rain forest
C. Tropical deciduous forest
D. Temperate evergreen forest

Answer

To determine which ecosystem type has the highest annual net primary productivity (NPP), we can follow these steps:

### Step-by-Step Solution:

1. **Understand Net Primary Productivity (NPP)**:
- NPP is defined as the rate at which all the plants in an ecosystem produce net useful chemical energy. It is a measure of the amount of organic matter created by photosynthesis minus the energy used by plants for respiration.

2. **Identify the Ecosystem Types**:
- The options provided are:
- A) Temperate Deciduous Forest
- B) Tropical Rainforest
- C) Tropical Deciduous Forest
- D) Temperate Evergreen Forest

3. **Analyze Each Ecosystem**:
- **Temperate Deciduous Forest**: These forests have moderate productivity due to seasonal changes and varying temperatures.
- **Tropical Rainforest**: This ecosystem is characterized by high temperatures and high humidity, receiving between 60 to 160 inches of precipitation annually. It is known for its rich biodiversity and high productivity.
- **Tropical Deciduous Forest**: These forests have a distinct dry season, which can lower their productivity compared to tropical rainforests.
- **Temperate Evergreen Forest**: These forests have lower productivity than tropical ecosystems due to cooler temperatures and less sunlight.

4. **Compare NPP Values**:
- Research shows that tropical rainforests have the highest NPP, estimated at around 9000 kcal/m²/year, significantly higher than the other types of forests listed.

5. **Conclusion**:
- Based on the analysis, the ecosystem type with the highest annual net primary productivity is the **Tropical Rainforest** (Option B).

### Final Answer:
**B) Tropical Rainforest**