If NEP is positive, what does that imply for the ecosystem's carbon?

• A. The ecosystem stores carbon
• B. The ecosystem releases carbon to the atmosphere
• C. The system is net negative for energy
• D. The system cannot photosynthesize

Answer: (A)

NEP measures how much carbon an ecosystem gains or loses, calculated as carbon fixed by photosynthesis minus carbon respired by all organisms. When NEP is positive, photosynthesis adds more carbon to the system than is released by respiration, so carbon builds up in biomass and soils. In short, the ecosystem acts as a carbon sink, storing carbon over time. This doesn’t say anything about energy balance or imply photosynthesis can’t occur; it just means photosynthesis exceeds respiration enough to net store carbon.