A Cost‐Efficient and Robust Approach to Monitor Ecosystem Photosynthesis Using Near‐Infrared Enabled Cameras

Photosynthesis is a fundamental biological process that supports nearly all life on Earth. The tropics contribute the majority of global photosynthesis; however, this region also faces the greatest challenges in monitoring photosynthesis using either ground‐based methods (e.g., logistics in deploying eddy covariance flux towers) or remote sensing (e.g., cloud contamination). In this study, we tested the use of a low‐budget near‐infrared enabled cameras (typically less than $5000 USD) to monitor gross primary productivity (GPP) across 26 sites spanning diverse ecosystem types. Across these sites, near‐infrared enabled cameras were collocated with eddy covariance flux towers, which provide continuous measurements of carbon exchange used to estimate GPP. We found that the camera‐based near‐infrared reflectance and photosynthetic active radiation (NIRvP) are strongly correlated with GPP, with the coefficient of determination ranging from 0.35 to 0.92. One unit of camera‐based NIRvP corresponds to 13–130 mol CO 2 /m 2 /s in GPP, largely depending on the radiation intensity and plant functional types of the site. The relationship between NIRvP—GPP obtained at the sites was extrapolated globally to estimate GPP using cameras at non‐eddy covariance sites. Our study demonstrates the potential of using near‐infrared enabled cameras as a cost‐effective and reliable method for estimating GPP, offering a valuable alternative for monitoring ecosystem productivity, particularly in tropical regions with sparse eddy covariance observations.