So, you’ve got a set of chambers and you want to measure greenhouse gas emissions such as CO2 flux from a site. Now what? You want to be able to accurately comment on C budget by quantifying the soil CO2 flux at a site, but there is an impressive (and daunting?) level of spatial and temporal variability in soil CO2 flux. Important questions arise: How many chambers do I need? Where do I place them? How often should I sample? First, it is important to consider the factors that influence soil CO2 emissions.