PRIMARY PRODUCTION PROCESS grazin g gain In light +C02 10-40% biomass 1040% 02 oxygen Net C02 Primary y(respiration) Production detrital (NPPl losses (decompos ition 40-10% autotro phs (s elf-feeders need Co2 heterotrophs (other feeders) 50% need 02 root roots nutrients losses structural >2 mm returned 20-40% fine <2mm