The Photosynthetic Response of Spectral Chlorophyll Fluorescence Differs Across Species and Light Environments in a Boreal Forest Ecosystem

•We characterize the variation in leaf spectral chlorophyll fluorescence in a forest.•Morphological traits dependent on species and light environment dominate the spatial variation•Photosynthetic and foliar pigment dynamics dominate the temporal variation.•Within-ecosystem variation in leaf morphology is critical for data interpretation.•The mechanistic link between fluorescence and photosynthesis depends on light history.