Which of the following is the best indicator of net primary productivity (NPP)?

• A. Weather (temperature & precipitation).
• B. Wind speed & direction.
• C. Biodiversity.
• D. Biomass.

Answer: (D)

Verified step by step guidance

1. Understand the concept of Net Primary Productivity (NPP): NPP is the rate at which all the plants in an ecosystem produce net useful chemical energy. It is the difference between the energy that plants produce through photosynthesis and the energy they use for respiration.
2. Recognize that NPP is directly related to the amount of biomass produced in an ecosystem. Biomass refers to the total mass of living organisms in a given area or ecosystem at a given time.
3. Consider why biomass is a good indicator of NPP: Since NPP measures the accumulation of energy in plant biomass, the more biomass present, the higher the NPP. Biomass reflects the net gain of energy stored in plant tissues.
4. Evaluate other options: Weather conditions like temperature and precipitation can influence NPP but are not direct indicators. Wind speed and direction do not directly measure NPP. Biodiversity refers to the variety of life and does not directly quantify energy production.
5. Conclude that biomass is the best indicator of NPP because it directly measures the net accumulation of organic material produced by photosynthesis, minus the energy used for plant respiration.