Fig. 1.
Seasonal dynamics of GPP, far-red SIF, NDVI, APAR, needle pigments, and fluorescence at Niwot Ridge, CO. (A) Phenocam (webcam) images of the canopy where the data were collected during different seasons. (B) Five-day running means of cumulative daily GPP (black) and true daily average SIF (dark red). (C) Five-day running means of NDVI (green) and APAR (gold). Shaded regions in B and C indicate 1 SEM. (D) Chlorophyll a + b concentration relative to dry mass (green), maximum quantum efficiency (Fv/Fm) measured with a fluorimeter (blue), and dark-adapted xanthophyll cycle conversion state (purple) ([Zeaxanthin + Antheraxanthin]/[Violaxanthin + Antheraxanthin + Zeaxanthin]) sampled at monthly intervals. All needleleaf measurements represent the mean and 1 SE of both Engelmann spruce and lodgepole pine samples during each 2- to 3-d sampling period.