Which of the following ecosystems would you expect to have the lowest net primary productivity?

• A. Temperate broadleaf forest.
• B. Tropical rainforest.
• C. Temperate grassland.
• D. The Sahara Desert.

Answer: (D)

Verified step by step guidance

1. Understand the concept of net primary productivity (NPP), which is the rate at which plants in an ecosystem produce net useful chemical energy. It is calculated as the difference between the energy captured during photosynthesis and the energy expended during plant respiration.
2. Consider the factors that influence NPP, such as sunlight availability, water availability, temperature, and nutrient availability. Ecosystems with abundant resources typically have higher NPP.
3. Evaluate the characteristics of each ecosystem mentioned: Temperate broadleaf forests, tropical rainforests, and temperate grasslands all have relatively high levels of sunlight, water, and nutrients, supporting higher NPP.
4. Contrast these ecosystems with the Sahara Desert, which is characterized by extreme aridity, limited water availability, and nutrient-poor soils, leading to very low NPP.
5. Conclude that the Sahara Desert, due to its harsh conditions and limited resources, would have the lowest net primary productivity among the ecosystems listed.