Answer;
-Time
Primary productivity is not limited by time.
Step-by-step explanation;
-Productivity is the increase in the amount of new living material produced (biomass) in an ecosystem. Primary productivity is the increase in plants in an ecosystem.This takes place mainly through photosynthesis.The Sun's energy is used by green plants(autotrophs) to make sugars out of water and carbon dioxide.
-The productivity of the primary producers is especially important in any ecosystem because these organisms bring energy to other living organisms by photoautotrophy or chemoautotrophy.