On Earth in per unit area maximum productivity occur in:

Options

A. tropical rain forest
B. Ocean
C. Temperate deciduous forest
D. Marsh.

Answer

**Step-by-Step Solution:**

1. **Understanding Productivity:**
- Productivity refers to the rate at which energy is produced in a given area, typically measured in terms of biomass or energy per unit area per year.

2. **Identifying the Options:**
- The options provided are:
1. Tropical Rainforest
2. Ocean
3. Temperate Deciduous Forest
4. Marsh

3. **Analyzing Each Ecosystem:**
- **Tropical Rainforest:**
- Located in equatorial regions, these forests receive abundant rainfall (200-350 cm/year) and have a warm climate. They are known for their high biodiversity and high productivity, estimated at around 12,000 kilocalories/m²/year.
- **Ocean:**
- While oceans cover a large area and have significant overall productivity, their per unit area productivity is generally lower than that of tropical rainforests.
- **Temperate Deciduous Forest:**
- These forests have a moderate productivity of about 300 kilocalories/m²/year, which is significantly lower than that of tropical rainforests.
- **Marsh:**
- Marshes can have high productivity, but they do not reach the levels of tropical rainforests.

4. **Comparative Analysis:**
- Comparing the productivity values:
- Tropical Rainforest: 12,000 kilocalories/m²/year
- Ocean: Lower than tropical rainforest
- Temperate Deciduous Forest: 300 kilocalories/m²/year
- Marsh: Generally lower than tropical rainforest

5. **Conclusion:**
- Based on the analysis, the ecosystem with the maximum productivity per unit area on Earth is the **Tropical Rainforest**.

**Final Answer:**
The maximum productivity on Earth in per unit area occurs in the **Tropical Rainforest** (Option 1).

---