Caribou-Poker Creeks Research Watershed (Alaska) Pulse-Amplitude Modulation Fluorometry Needle-Scale Observations (March 2022 - July 2024)

This dataset consists of pulse-amplitude modulation (PAM) fluorometry data collected using six Micro-PAM (Walz GmbH, Effeltrich, Germany) measurement heads installed on two black spruce trees at the Caribou-Poker Creeks Research Watershed National Ecological Observatory Network (NEON) site (site abbreviation: BONA) near Fairbanks, Alaska. These measurements provide information on the physiological status of photosystem II and photosynthesis more broadly for the needles and trees observed. Three PAM measurement heads were installed on each tree at low, intermediate, and high heights qualitatively within the canopy. Five measurement heads (second intermediate position measurement excluded) were installed in March 2022, with the sixth measurement head being installed in July 2022. Data was collected semi-continuously, including the harsh winter season, until July 2024. PAM fluorescence measurements were collected in a ramped scheme centered around noon to maximize measurement frequency while still allowing for adequate dark acclimation for the nighttime measurement. Saturation pulses were performed by each measuring head every fifteen minutes from 9:00AM – 5:00PM, every thirty minutes from 7:00AM-9:00AM and 5:00PM-7:00PM, and every hour from 2:00AM-7:00AM and 7:00PM-9:00PM.