Secondary productivity is the rate of formation of new organic matter by consumers.

Answer

**Step-by-Step Text Solution:**

1. **Understanding Productivity**:
- Productivity in an ecosystem refers to the rate at which energy is converted into organic matter. It is crucial to differentiate between primary and secondary productivity.

2. **Primary Producers**:
- The process of productivity begins with primary producers, which are typically plants. They perform photosynthesis to convert sunlight into chemical energy, resulting in the formation of organic matter or biomass. This is referred to as **Gross Primary Productivity (GPP)**.

3. **Net Primary Productivity**:
- Not all the biomass produced by plants is available for consumption. A portion of it is used by plants for respiration. The remaining biomass, which is available for consumption by herbivores and decomposers, is known as **Net Primary Productivity (NPP)**.

4. **Role of Consumers**:
- Herbivores (primary consumers) feed on the net primary productivity of plants. They utilize this energy to grow and reproduce, leading to the formation of new organic matter. Decomposers also play a role by breaking down dead organic matter, returning nutrients to the ecosystem.

5. **Secondary Productivity**:
- The new organic matter formed by consumers (both herbivores and carnivores) from the energy they obtain from NPP is termed **Secondary Productivity**. This represents the rate at which consumers convert the energy from the food they consume into their own biomass.

6. **Conclusion**:
- In summary, secondary productivity is the rate at which new organic matter is formed by consumers in an ecosystem, utilizing the energy derived from the net primary productivity of plants.

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