Calculating carbon emissions and sequestration due to biological processes is complex.
An ecosystem is both drawing CO2 out of the atmosphere (photosynthesis) and releasing it (respiration), so we need to understand the net difference in those processes. And the rates of these processes differ based on land cover type (crop, forest, etc), region, weather, historical and current land management practices, and more. It gets complicated quickly.
So how do we incorporate all these dynamics to understand CO2 flux in nature? NEE.
Direct measurements of NEE account for all of the aforementioned variables, making it a fantastic parameter to track CO2 flux in productive ecosystems and nature-based solutions in a holistic way.