C Fluxes between Major Terrestrial and Aquatic Components State Variables (Pools) Rate Variables (Influxes/Effluxes) Atmosphere to Phytosphere Atmospheric CO2 concentration NPP and GPP Biosphere to Atmosphere Living community biomass Re, Rh and Ra Lithosphere to Atmosphere Soil (in)organic C [Sedimentary (in)organic C] Rs/[sedimentary respiration and diffusion of dissolved C and bicarbonates] Biosphere to Lithosphere Dead community biomass Litterfall/[sinking of particulate organic C] Anthroposphere to Atmosphere Ecosystem- or biome-scale C sources NEE (NEP), NBE (NBP), burning of fossil fuels, transition to renewable energy sources, land-use/cover changes and management practices Atmosphere to Anthroposphere Ecosystem- or biome-scale C sinks NEE (NEP), NBE (NBP), policy/land use decisions and management practices The bracket sign “[ ]” was used to depict specific aquatic components. Terrestrial community biomass refers to the sum of aboveground and belowground plant and animal biomass, while aquatic community biomass refers to that of aquatic plant, phytoplankton, zooplankton and fish biomass. Rs = Soil (microbial + plant root) respiration. The term “anthroposphere” was used to denote human-induced regimes of both disturbances and rehabilitation/restoration practices. The term “lithosphere” ” was used to denote the soil and bottom sediment conditions of the terrestrial and aquatic ecosystems, respectively.

Table 1: Major state and rate variables of C cycles in terrestrial and aquatic ecosystems.