above ground net primary production
grassland
biomass
plant material
heterotrophic soil respiration
carbon dioxide 
flux
soil carbon content
soil
phytoplankton productivity
carbon
concentration
dissolved carbon dioxide 
carbonate or 
bicarbonate
water
aquatic system
ecosystem 
carbon flux
carbon dioxide flux
an enrichment experiment
growth
trees 
diameter 
net primary production
coastal macroalgae
carbon per area per time
ocean carbon dioxide flux