Final answer:
Net productivity is calculated by subtracting respiratory losses from gross primary productivity, yielding the energy available to primary consumers; for the Silver Springs example, it is 7,623 kcal/m²/yr. It represents the energy after primary producers have met their metabolic needs.
Step-by-step explanation:
Based on the given data, the net productivity can be determined by subtracting the respiratory losses from the gross primary productivity. The given example states that 13,187 kcal/m²/yr are used for respiration or are lost as heat out of a total gross primary productivity of 20,810 kcal/m²/yr. Thus, the net productivity, which represents the energy available to the primary consumers, would be 20,810 kcal/m²/yr - 13,187 kcal/m²/yr = 7,623 kcal/m²/yr.
Net productivity, specifically net primary productivity (NPP), is a key concept in ecosystem energetics. It represents the amount of energy that is left after primary producers have utilized some part of the energy they captured from the sun for their own metabolic processes such as respiration. This remaining energy is what is indeed available to the organisms at the next trophic level, the primary consumers, for growth and reproduction, making it a cornerstone in understanding the flow of energy through an ecosystem.