biostudies-literatureUnknown17(1)Zhao RThe terrestrial biosphere exchanges a large amount of CO₂ with the atmosphere through photosynthesis and respiration, determining the magnitude of land carbon sink and consequently influencing the rate of global warming. The magnitudes of global photosynthesis and respiration, however, vary widely across models (100-200 PgC/year), constituting a key and persistent source of uncertainty in carbon cycle and climate modelling. Here, we argue that the uncertainty in the land carbon cycle modelling is largely attributable to the uncertainty in biogeography - the distribution of plant functional types (PFTs). Using an ensemble of dynamic global vegetation models (DGVMs), we find a strong dependence of total photosynthesis on total area for each PFT. The dependence allows us to reduce Nature communications912https://www.ebi.ac.uk/biostudies/studies/S-EPMC12830893biostudies-literatureVegetation biogeography is a main source of uncertainty in modelling the land carbon cycle.PMC12830893Zhao RHoffman FMWalker APKoh LPLuo XfalseVegetation biogeography is a main source of uncertainty in modelling the land carbon cycle.The terrestrial biosphere exchanges a large amount of CO₂ with the atmosphere through photosynthesis and respiration, determining the magnitude of land carbon sink and consequently influencing the rate of global warming. The magnitudes of global photosynthesis and respiration, however, vary widely across models (100-200 PgC/year), constituting a key and persistent source of uncertainty in carbon cycle and climate modelling. Here, we argue that the uncertainty in the land carbon cycle modelling is largely attributable to the uncertainty in biogeography - the distribution of plant functional types (PFTs). Using an ensemble of dynamic global vegetation models (DGVMs), we find a strong dependence of total photosynthesis on total area for each PFT. The dependence allows us to reduce 2025-01-01T00:00:00Z2025 Dec2026-06-13T05:13:24.454Z2026-06-13T03:08:05.834ZS-EPMC128308934140768510.1038/s41467-025-67636-1