Significance: Evergreen photosynthetic activity has been difficult to determine from remote sensing, causing errors in terrestrial photosynthetic carbon uptake models. Using a reflectance chlorophyll/carotenoid index (CCI) sensitive to seasonally changing chlorophyll/carotenoid pigment ratios, we demonstrate a method of tracking photosynthetic phenology in evergreen conifers. The CCI reveals seasonally changing photosynthetic rates and detects the onset of the growing season in evergreen foliage. This method could improve our understanding of changing photosynthetic activity in a warming climate, and could improve assessment of the evergreen component of the terrestrial carbon budget, which has been elusive.

Summary: A new proliferation of optical instruments that can be attached to towers over or within ecosystems, or ‘proximal’ remote sensing, enables a comprehensive characterization of terrestrial ecosystem structure, function, and fluxes of energy, water, and carbon. Proximal remote sensing can bridge the gap between individual plants, site‐level eddy‐covariance fluxes, and airborne and spaceborne remote sensing by providing continuous data at a high‐spatiotemporal resolution. Here, we review recent advances in proximal remote sensing for improving our mechanistic understanding of plant and ecosystem processes, model development, and validation of current and upcoming satellite missions. We provide current best practices for data availability and metadata for proximal remote sensing: spectral reflectance, solar‐induced fluorescence, thermal infrared radiation, microwave backscatter, and LiDAR. Our paper outlines the steps necessary for making these data streams more widespread, accessible, interoperable, and information‐rich, enabling us to address key ecological questions unanswerable from space‐based observations alone and, ultimately, to demonstrate the feasibility of these technologies to address critical questions in local and global ecology.