Gross primary production (GPP) of tallgrass prairie near Manhattan, Kansas was calculated from eddy covariance measurements of net ecosystem CO₂ exchange (NEE) and automated chamber‑based estimates of total ecosystem respiration (Rt). To determine spatial variation in carbon fluxes, soil respiration and hyperspectral reflectance were measured on transects that bisected the footprint of the flux tower as well as all other landforms in the catchment of a watershed. A simple modeling approach based on temporal stability and landform position was used to estimate mean GPP, NEE, and Rt at the watershed scale.