Plants produce CO2 as well, photosynthesis is only used to produce sugars, normal respiration (I.e. sugars + O2 = energy + CO2), is used by plants to consume th

Plants produce CO2 as well, photosynthesis is only used to produce sugars, normal respiration (I.e. sugars + O2 = energy + CO2), is used by plants to consume those sugars. Only a plant cells containing chlorophyll and exposed to sunlight will photosynthesise. Notably at night there isn’t much sunlight, so normal respiration dominates a plants gas conversion processes, and results in them producing net CO2. Based on the graphs in the blog post, I assume GP is placing the CO2 production on plants because it the CO2 levels peak at night, then return to normal every morning.